bio 354 exam 2
Harvesting Overfishing: is a major problem
"Tragedy of the commons" - resource held in common --no incentive to stop harvesting --results in overexploitation --several stocks declining --development of other approaches
Mutualism
(+,+) both species benefit --mutualism usually involves complementary functions
Birch's competition lab experiment
*Birch's grain beetle experiment* -tested beetles at several different temperatures ...found that at 29deg the Calandra would eliminate the Rhizopertha..... but at 32deg the Rhizopertha would eliminate the Calandra ---he said he could predict these results from the intristic capacity for increase ... so he would do this by changing only one component of the environment, temp by 3deg OUTCOME: *competitive exclusion*
kobe plot
*Kobe plot* -- shows whether a pop is overfished and/or overfishing is occurring graph: overfished vs. overfishing -bottom left and upper right hand corner (yellow) = one of the 2 ......either the harvest rate and biomass are low or both are high -upper left (red) = both .. harvest rate and stock biomass are low -lower right (green) = neither ... low harvest rate and high stock biomass
effects outside marine reserves
*spillover* -- the movement of individuals from inside to outside reserves 1. juveniles and adults (mobile species only) -home range movements... if you put a reserve in the middle of a species home range then that indiv is always in and out of the reserve because thats its natural range -ontogenetic migration.. protected when young then migrate out when they are grown -competitive interactions.. could be intracompetition within species bc species increase in size but resources remain the same so it might be more beneficial to move to a different habitat -higher mobility = less protection from reserve 2. larvae (both mobile and sessile) -larger fish produce disproportionately more larvae (fecundity increases exponentially with body mass .. a fish twice the size of another produces more than twice the amount of larvae) -hard to track where they go -microchemistry -genetics (on nemos) -biophysical circulation methods (currents)
Where might the impacts of SWS be stronger?
In Point Loma: Henrica, P. Giganteus and P. Brevespinus all found in the subtidal zone at Point Loma
The abundance of the higher-profitability food.
In prey choice, what affects which food to take?
Why might parasites with complex life cycles frequently alter host behavior?
Increase susceptibility of host to predation by the next host.
effects of ocean reserves
Increased: (but there is a lot of spread in data) -abundance -indiv size -biomass -diversity -only 0.01% of ocean is a reserve VARIABILITY bc.. -design characteristics (size, location) -amount of fishing outside/before establishment -enforcement -other environmental impacts (pollution) ex) reserves could cause a trophic cascade where small unfished species decrease because their predator species has increased in the reserve ex) sheepheads increased, kelp increased, sea urchins decreased
Exploitation
Interaction between populations that enhances fitness of one individual while reducing fitness of the exploited individual.
Neutralism
Interactions between two species that have no effect on either species
Obligatory Mutualism
Interactions required for survival of one or both species -ex: gut bacteria
Winners and losers of interference or exploitative?
Interference: WINNER -When two species compete, One will dominate over the other. Exploitative: All species are usually LOSERs. Fighting for same limited resource, which in turn drives it down and all suffer over time.
Individuals of one sex consistently choose mates among members of opposite sex based on a particular trait
Intersexual selection
Individuals of one sex compete among themselves for mates
Intrasexual selection
Which competition is stronger according to the Lotka-Volterra model when two species coexist?
Intraspecific competition
Introduced species
Invasions of exotic species: intentional or accidental introductions
Ecosystem-based management
Is more modern & complex, plans take into account a broader range of species perspective. This type plan also seeks to maintain ecosystems, as opposed to a single species or single ecosystem funtion
Growth Efficiency
Is the ability of animals to convert their own tissue.
Types of mutualism
Is the interaction required for survival -Facultative mutualism: not required -Obligatory mutualism: required
Where have exteinctions due to introduced species been the most severe?
Islands
the model draws attention to some aspect of the environment by its activities there where the observer learns more on its own by individual learning
Local enhancement
A modified form of the logistic equation used to model competition. The more similar 2 competing species are in their use of resources, the more likely it is that one will drive the other to extinction
Lotka-Volterra competition model
Theory on competition
Lotka-Volterra equation of competition between species Tilman Model
Allee effect
Lower than expected population growth in small popullations -females fail to find mates -fertilization rates of spawners dependent on sperms concentration What types of species likely would be most affected? Secondary species, rare species
What type of species are affect by SWS
Many Pisaster (a keystone species) are affected, as well as morning sun stars, and mottled stars.
n-dimensional hypervolume
Many factors that contribute to an organisms niche
Management and conservation
Marine protected areas=fishing limited to locals or banned on a seasonal basis No-take zone=all fishing is prohibited
Do marine systems support local adaption factors?
Marine systems have less adaptation because of larval dispersal, which gets rid of adaptation to the habitat the adult resides in.
Periodic
Maximizing probability of surviving in habitats with infrequent period of favorable conditions for reproduction
Opportunistic
Maximum colonizing ability in habitats that vary unpredictably
Small populations
Minimum viable populations -smallest population that will persist
This mechanism is the only mechanism that leads to adaptation to changing environmental conditions.
Natural Selection
Faculative Mutualism
Not required for survival
Competitive Exclusion
One species excludes the other from some area via COMPETITION -Common in LAB studies
Defensive mutualism
One species protects another in return for a "reward" Example: ant and swollen-thorn acacia mutualism Characteristics of the acacia: beltian bodies, nectaries, horn-shaped thorns Characteristics of the ants: nest in thron, use nectaries and Beltian bodies for food, "defend' acacia against herbivores and competitors
Amensalism
One species/organism is harmed while the other is unharmed.
training that a response leads to a reward/removal of a punishment
Operant conditioning
foragers can't search for more than one food at a time, search time per day is limited
Optimal foraging theory assumptions
Plant defense hypotheses
Optimate Defense Hypothesis Resource availability hypothesis
Optimate Defense Hypothesis
Organisms allocate defenses to maximize individual fitness, and defenses are costly to produce -- apparent vs. unapparent plants "apparent" plants: easily found by herbivores--chemicals in large concentrations "unapparent" plants: not easily found (e.g., small, rare, short-lived)--chemicals in small concentrations
Competiton
Organisms of the same, or different species use common resources or harm one another while acquiring resources
TMIIs
PREDATOR Avoidance- One species induces a change on another species, which in turn causes a trait change and interactions with the 3rd species. -Release of chemical cues that causes the intermediate to hide to stay away from danger -Crabs can affect the abundance of seaweed, by causing snails to hide unintentionally
Coexistence: Lab 2
Paramecium: two species feeding on yeasts -Feed at different depths on a glass and using different habitats.
How do trematode parasites interact indirectly with emphemeral algae?
Parasite affects trait in snails which affects their grazing, and in turn, effects algal growth
Under which environmental conditions are mutualisms favored?
Physically stressful environments & environments under high consumer pressure
What defense mechanisms do plants have against herbivores?
Plants can induce chemcial defenses, which make the plant taste bad.
Population persistence
Population persists through time
DMIIs
Predator eats prey, changing density in population which affects 3rd species. -Change in intermediate trophic
Predator-Prey Oscillations
Predator-prey interactions may produce regular "cycles" in abundance Example: Lynx-hare cycles see lecture 9
What responses can predators have to prey?
Predators can learn to avoid prey if they are chemically defended. Warning coloration in prey alert "trained" predators that they are toxic or unpalatable
How does predation modify the intensity of competition?
Predators relax competition by removing more competitive individuals (intraspecific competition) or species (interspecific competition). Predators confine prey to habitats in which resources for their prey are limited. Thus, competition among prey can be greater.
Conservation Ecology
Preservation & Management of biodiversity and natural resources
case study : west coast rockfish
Problem: -environmental variability = year class failures -failure to make timely decisions to change harvest rate -lack of data -overcapitalization of fishing fleet.. too much money already invested - similar to the anchovy collapse bc of El Nino --rockfish are a cold water group and in order to recruit successfully.... during warm years, recruitment dropped and we did not realize it soon enough (Pacific Decadal Oscillation- current that brings in cold water) -huge biomass declines
case study : pacific bluefin tune
Problem: overfished -high demand/value -highly migratory species -multiple management agencies involved -catches are variable -spawning biomass estimated at about 4% of unfished levels (very very very low biomass) -tighter quotas have been implemented -new countries like Mexico have started fishing the bluefin also which *impacts the early ages and they havent had a chance to reproduce*
Stock-recruitment relationships
Provide a basis for predicting recruitment given size of spawning stock Assumption: Spawner-recruitment relationship constant over time Problems: Empirical data do not match expected relationships (known as the "recruitment problem") figure see lecture 11 p5
Competition has important proximal and ultimate effect
Proximal-> reduces availability of resources Definition in the context of proximal effects. Use or defense of a resource by one individual that reduces the availability of that resource to other individuals. Ultimate-> reduction in fitness That results a decreased contribution of individuals in future generation (i.e., reduction in fitness) <-- Ultimate effects
Age distribution
Reflects a population's history of survival, reproduction, and growth potential
Prey have protection from predators
Refuges -Escape in spcace -Escape in size -Escape in number (swamping predators)
Commensalism
Relationship where one species/organism benefits and the other is unharmed
Herbivory
Relationships between herbivors and plants Defense mechanisms in plants: -structural (e.g., spines, tough cuticle) -chemical (secondary substances; metabolic by-products) -defenses can be inducible see figure lecture 10 p1
Numerical Response by predators to their prey
Response of predator population to change in prey density (i.e. predator density increases due to reproduction)
Sea Star Wasting Syndrome?
SWS is where an ifected sea star begins to show lesions on its body before eventually "melting", wasting away and dying.
Chains of extinctions
Secondary extinction of species that depend on species that have become extinct -example: large predators become extinct after their prey are extinct
when an animal learns to become more sensitive to a stimulus over time.
Sensitiziation
Metapopulations
Series of subpopulations linked by dispersal Single subpopulations go extinct or are recolonized "frequently", but the overall metapopulation is maintained
As N approaches K (Carring compacity) growth slows.
Sigmoidal population growth
What is the extinction vortex?
Small populations lead to higher chance of inbreeding and random genetic drift, which leads to a loss of genetic variability, which leads to reduction in fitness, which leads to lower reproduction and higher morality, which leads to small populations (and the cycle repeats itself)
model is present, not doing anything important, observer is drawn to the area because of the presence of the model where it subsequently learns something about the environment on its own.
Social facilitation
Resources
Something that's consumed abundance reduced by consumption used by organisms for growth and maintenance reduction in resources reduces population growth important when they are limited
Source-sink dynamics:
Source population: -high quality habitat -produces extra individuals -net exporter (E>I) Sink population: -poor quality habitat -produces few if any individuals -populations persist here because of immigrants from the source (I>E)
Why do we observe co existence much more commonly in nature than predicted?
Species specialize on different resources, which reduce niche overlap and competition. This specialization is produced by natural selection
Equilibrium
Stable, highly competitive conditions
Normal random changes to a population that cause its extinction.
Stochastic extinction
This mechanism leads to speciation within the same geographic area.
Sympatric speciation
Theoretical and importance of DMII + TMII
TMII- a single predator species can effect multiple prey DMII- a single predator can eat a FIXED number of prey. While the predator is eating the prey, it can affect and scare the rest of it's population as a whole
How do herbivores interact?
TMII. One herbivore species attacks its prey, which then causes a CHEMICAL defenses trait change that has a negative effect on another herbivore. -Can battle one another indirectly.
4 responses of predation (Total Response)
TOTAL RESPONSE = numerical + functional responses reproduction + aggregative response = numerical response feeding response + developmental response = functional response 1. *functional response* -response of an average predator to the abundance of the prey - # prey eaten changes 2. *numerical response* -response of a predator population to a change in prey density -density increases by reproduction 3. *aggregative response* -individual predators move into and concentrate in certain areas within the study area 4. *developmental response* -individual predators eat more or fewer prey as predators grow toward maturity (increased growth rates) IF WE CAN MEASURE ALL OF THESE... -*total response* gives the percentage of prey organisms eaten per unit time by the entire predator population plotted against prey density -if the total response INCREASES as prey density INCREASES.. the predator may limit the density of the prey -if the total response remains CONSTANT or FALLS as prey density increases ... the predator cannot limit prey numbers
What has caused population growth?
The Crude Birth Rate has exceeded the Crude Death Rate
Which organism is likely responsible for SWS?
The Densovirus
Predation
The act of one organism killing another
Realized Niche
The actual niche of a species due to both physical limitations and interspecific competition
Realized Niche
The actual set of factors observed in the presence of compettion;competition (or other interactions) limits a species from "filling" the fundamental niche
Realized Niche
The actual set of factors observed. Competition and other factors may limit a species from "filling" the fundamental niche
Why might introduced species cause TMIIs to fail?
The argument is that if these cues are predator-specific, prey might not have evolved the ability to respond to the introduced predator. There is no shared eolutionary history between the introduced predator and the native prey.
quality of the relative food, distance between patches, cost associated with switching patches(eg risk of becoming prey)
The factors that affect the rate of switching food patches
what to eat, how long to stay foraging in a patch, how do nutrient requirements affect foraging, how does variation in food supply affect decisions
The four choices of optimal foraging theory
What is ghost of competition past?
The idea that we don't see competitive exclusion in the real world because what we are seeing are the effects of competition over long evolutionary time
2 herbivore interactions
The interactions of 2 herbivores cause and affect and change on the 2nd tropic level species. -An herbivore attacks prey, and increases CHEMICAL defenses so it encounters lower quality and is toxic.
Fundamental Niche
The physical conditions under which a species might live in the absence of competitors
Why did ecologists originally speculate that local adaptation should be less common in the sea?
The potential for dispersal is greater for marine organisms. Organisms could have genetic exchange between different organisms and reduce ability to adapt to environment (disrupts selection on local populations).
What is a likely factor that led to the evolution of sexual reproduction?
The relative rates of evolution in hosts and parasites
What is the life or dinner principle?
The relative strength of selection of predator & prey. Selection is stronger on prey. If predator loses, it misses a meal. If prey loses, it loses its life.
Competition
The use of defense of a resource by one individual that reduces the availability of that resource to other invidiuals....that results in a decreased contribution of individuals in a future generations.
What do populations grow geometrically?
Things to note (the Geometric Model): -Growth is multiplicative and not additive -Population quickly becomes unrealistically large -A fundamental law of ecology: population cannot grow geometrically for very long
What is the extent of SWS outbreak?
This extent is severe and certain areas have shown complete die-off of certain species.
What is the paradox of the plankton; how was it resolved?
This paradox goes against the competitive exclusion principle, as a limited resource supports a wide range of plankton. This paradox is slightly resolved, as planktonic systems go through extreme fluctuations.
Population regulation
Two important observations: -Abundance varies from place to place and over time -Populations can't grow geometrically for very long -Logistic growth model & carrying capacity
Why are TMIIs important?
Ubiquitous and a single predator can affect on communities as it causes changes and effect many prey.
Macroparasites
Various invert taxa (nematodes, plathyleminthes, arthropods, ecct.) but few vertebrates and plants too.
Microparasites
Viruses, bacteria, fungi, prions (protein bodies)
energy, encounter rate, handling cost, profitability
What are the factors to consider when choosing food?
Function of mutualistic interaction
What is the function of the interaction? Trophic mutualism Dispersive mutualism Defensive mutualism
When does competition occur?
When organisms reduce the availability of a shared resource by use or defense Resource must be limited
What are possible preasons why the responses of native snails to introduced green crabs differs between the East & West Coasts of the U.S.?
When the green crab is introduced in the west, the snails did not respond to it as they had no evolutionary history. When the green crab is introduced in the East Coast, the snails showed a TMII response. This possibly due to previous interactions with the green crabs, or some connection in evolutionary history.
Competition
Within trophic levels competition. -Can be with one species or with two different species that compete for resources
Examples of some populations display sigmoidal (S-shaped) growth curves
Yeast and Barnacles
Have infected sea stars been discovered in San Diego?
Yes
Umbrella Species
a species whose conservation indirectly benefits other species within an ecological community
Predator avoidance tactics that are used primarily to disrupt prey handling include a. a hard body covering. horns, or antlers.
a. a hard body covering. horns, or antlers.
In the Lotka-Volterra predator-prey model, a predator population in the absence of prey would Select one: a. decline exponentially.
a. decline exponentially.
Gene flow Select one: a. increases with immigration/migration. b. is more common in large populations than in small populations. c. always increases adaptation. d. leads to genetic drift in small populations. e. is less common in large populations than in small populations.
a. increases with immigration/migration.
Qrganisms with a type-I survivorship curve have a. low mortality during most of the life span and high mortality in older age classes
a. low mortality during most of the life span and high mortality in older age classes
The fundamental niche of an organism refers to Select one: a. the physical conditions under which a species might live in the absence of biotic interactions. b. the distribution of an organism in its environment.ility.
a. the physical conditions under which a species might live in the absence of biotic interactions
Density-independent factors
abiotic factors, disturbance
the number of individuals in a species that are found in a given area.
abundance
the frequency of an advantageous trait in a population increases over time. caused by natural selection.
adaptive evolution
occurs when a group of organisms give rise to many new species whose adaptations allow them to fill new or vacant ecological roles in their communities.
adaptive radiation
The proportions of a population in each age class.
age structure
Niche
all of the environmental factors related to a growth, survival and reproduction
niche
all the environmental factors related to a species' growth, survival, and reproduction (intimately involved with competition exclusion principle) 1. resources 2. physiological tolerances 3. "n-dimensional hypervolume" Hutchinsons redefinition of the niche: if we consider just 2 environmental factors, such as temp and precipitation, and determine for each species the range of values that allow the species to persist, we can produce an analysis on *realized niche*... measure other environmental variables until all the environmental factors have been measured *fundamental niche*: in an ideal world we could measure the ecological space occupied by the species in the absence of competition and other biotic interactions ... set of resources a species can utilize in the absence of other organisms ---abstract concept that we cant really measure
Niche
all the environmental factors relevant to a species growth, survival and reproduction
Fundamental Niche
all the environmental factors relevant to a species survival reproduction;an abstact concept and requires the absence of other organisms
A decrease in the population growth rate (r or λ) as the population density decreases.
allee effect
yield
amount of usable material taken from a harvested population, measured in numbers or biomass -always involves units over time (year)
Which of the following is NOT an acceptable definition of evolution? Select one: a. a change in the genetic makeup of a population. b. a change in the genetic makeup of an individual. c. a process where the genetic variability of a population changes as a result of the migration of individuals between sub-populations. d. a process where populations become adapted to local environmental conditions through natural selection.
b. a change in the genetic makeup of an individual.
_______________________ is the type of natural selection that occurs when smaller deer are at a competitive disadvantage than average sized or larger deer. a. stabilizing selection b. directional selection c. Disruptive (diversifying) selection d. Kin selection e. Sexual selection
b. directional selection
An interaction where two hyenas in the African savanna vie for the same gazelle for food is called a. mutualism. b. intraspecific competition. c. character displacement. d. interspecific competition. e. resource partitioning.
b. intraspecific competition.
Globalization and the transport of goods all over the world can facilitate ________________ dispersal of exotic, invasive species. Select one: a. secular b. jump c. diffusion d. drift e. random
b. jump
A situation where different plant species are growing together but acquiring resources from different soil depths is a good example of Select one: a. density dependent population growth. b. resource partitioning.
b. resource partitioning.
A zero-net growth isocline in the Lotka-Volterra model of interspecific competition depicts Select one: a. the population size of a predator species when the growth rate of the prey population is zero. b. the combination of population densities where the net growth of a given population is zero. c. the combination of population densities where the density of a given population is zero. d. the population size of a prey species when the growth rate of the predator population is zero. e. the population size where competition leads to competitive exclusion.
b. the combination of population densities where the net growth of a given population is zero.
In the Lotka-Volterra competition equations, if the competition coefficient a < 1, then a. the population growth rate of species I is reduced more by each individual of species 2 than by each individual of species 1 b. the population growth rate of species I is reduced more by each individual of species I than by each individual of species 2. c. there is no intraspecific competition. d. None of the above.
b. the population growth rate of species I is reduced more by each individual of species I than by each individual of species 2.
Lotka-Volterra models
based on logistic curve of population growth dN1/dt=r1N1([K1-N1]/K1) dN2/dt=r2N2([K2-N2]/K2)
Tilman's models
based on resource limits and resource consumption rates
Tilman Model (graphical model)
based on resource limits and resource consumption rates (mechanisms of competition Competition can lead to (1) exclusion of species, or (2) coexistence of species Understanding competition: knowing the resources that are limited and the mechanisms of competition Example: Territoriality: (Intra/inter specific, interference)-- by defending an area, you defend resources (common in birds, reef fishes, some mammals)
Population density & population size
birth and death rates and population equilibrium Equilibrium occurs when per capita birth & death rates are equal see lecture 11 p2 Popullation size is influenced by both density-dependent and density-independent per capita birth and death rates
Limitation of the abundance of a population by nutrient supply or by the availability of food.
bottom-up control
Character displacement refers to Select one: c. an evolutionary process where competition results in niche divergence. d. the interaction that occurs when the realized niche of two species closely overlaps. e. the interaction that occurs when the niche breadth of two species is the same.
c. an evolutionary process where competition results in niche divergence.
Human population growth has increased globally over the last century because Select one: a. the need for labor has caused a global increase in fertility. b. immigration rates have increased. c. birth rates have exceeded death rates. d. fertility rates in developing countries have increased. e. fertility rates in developed countries remain higher than in developing countries.
c. birth rates have exceeded death rates.
Constitutive defenses against herbivory are a. chemical compounds that are similar to insecticides. b. synthesized immediately after the herbivore damages the plant. c. chemical and/or structuial properties that are a relatively stable part of a plant's allocation. d. specialized chemical compounds that are toxic to herbivores. e. All of the above
c. chemical and/or structuial properties that are a relatively stable part of a plant's allocation.
Hardy-Weinberg Equilibrium is NOT possible when Select one: a. populations are isolated. b. there are no net mutations. c. populations are small. d. natural selection does not cause adaptation. e. mate selection is a completely random process.
c. populations are small.
With exponential growth, Select one or more: a. N-K represents the carrying capacity. b. population size increases more rapidly when N exceeds K. c. resources are unlimited. d. populations grow more slowly as N nears K. e. populations may be colonizing new habitat. f. resources are limited by the population carrying capacity g. K-N represents linear density dependence.
c. resources are unlimited. e. populations may be colonizing new habitat.
The realized niche of an organism refers to a. the physical conditions under which a species might live in the absence of a competitor. b. the dispersal of an organism in its environment. c. the functional role of the organism due to both physical and biotic (competition, predation) limitations d.the rate in which an organism uses resources along a gradient of resource availability.
c. the functional role of the organism due to both physical and biotic (competition, predation) limitations
indirect effects of predation
carnivores I (direct, negatively effect) V herbivores I (direct, negatively effect) V producers BUT carnivores positively effect producers *indirectly*= *trophic cascade* cascade impacts: ex) 1. killer whales increase 2. sea otters decrease 3. sea urchins increase 4. giant kelp decrease ex) 1. sea otters increase 2. sea urchins decrease 3. giant kelp increase
The maximum population size that can be supported indefinitely by the environment, represented by the term K in the logistic equation.
carrying capacity
change in population biomass (exploitation)
change in biomas = growth + recruitment - natural mortality - fishing mortality
Evidence for character displacement
changes in the morphology of species when they occurs sympatrically vs. allopatrically Example: Galapagos Finches
A process in which competition causes the phenotypes of competing species to evolve to become more different over time, thereby causing the species to become more different where they live together than where they live apart.
character displacement
a pattern of gradual change in a characteristic of an organism over a geographic region
cline
a dispersion in which individuals are grouped together.
clumped dispersion
The evolution of two interacting species, each in response to selection pressure imposed by the other.
coevolution
A life table in which the fate of a group of individuals born during the same time period (a cohort) is followed from birth to death.
cohort life table
compartment models ... to model disease outbreaks
compartment models - population "compartmentalized into different groups" -useful for answering questions about the stability of host-disease interactions 1. *SIR* model: susceptible - infective - removed -host population is characterized by relative sizes of the 3 compartments and birth and death -in this model organisms become immune and the epidemic dies out -rate of change in susceptible pop = rate of transmission from infected to susceptibles -rate of change in infected population = rate of transmission from infected to susceptibles - rate of recovery of infected individuals -rate of change in the recovered population = rate of recovery of infected individuals if there is NO RECOVERY (y=0) than we have an SI model (not SIR, because there is no recovery) Ro = average number of secondary infections produced by one infected individual (B/y)... an epidemic can develop only if Ro>1 Ro = reproductive number... is >1 for disease to spread (BN/y) parameters: -alpha = per capita rate of disease mortality -v = per captia recovery rate of hosts -B = transmission rate -gammy (y) = per capita rate of loss of immunity -Z = dynamics of the recovered individuals -Y = infected individuals -X = number of susceptibles -N = total number of indivs (X + Y + Z)
An adaptive growth response of plants to herbivory in which removal of plant tissues stimulates the plant to produce new tissues.
compensation
An interaction between individuals of two species in which each is harmed by their shared use of a resource that limits their ability to grow, survive, or reproduce (a -/- relationship).
competition
interspecific
competition between species
A constant used in the Lotka-Volterra competition model to describe the extent to which an individual of one competing species decreases the per capita growth rate of the other species.
competition coefficient
intraspecific
competition within species
The principle that two species that use a limiting resource in the same way cannot coexist indefinitely.
competitive exclusion principle
How does competition modify the intensity of predation?
competitors may make individuals more susceptible to predators
Gause's hypothesis (competitive exclusion principle)
complete competitors cannot coexist -if there is no differentiation between the niches of 2 competing species then one species will eliminate or exclude the other LAB experiment: -studied mechanism of competition between two species of yeast 1. grew the 2 populations *in isolation* and found that the population growth of both species was sigmoid and could be fit my the logistic curve 2. grew the 2 populations *together* and found that it fit the Lotka-Volterra equation ....... ethyl alcohol was the limiting factor of growth not food supply..... so competition coefficients can be determined by a direct ration or alpha and beta ....... the alpha value changed however and so he decided that it is limited by another resource and the competition coefficients would be the reciprocals of each other ... but this does not apply to all cases of competition ANOTEHR EXPERIMENT -- found that two species of paramicium could live in a tube of yeast indefinitely and *coexist* because of a difference in feeding behavior ---situations where competitive exclusion will NOT OCCUR: 1. unstable environments that never reach equilibrium and are occupied by colonizing species 2. environments in which species do not compete for resources 3. fluctuating environments that reverse the direction of competition before extinction is possible CAN BE REJECTED as a general model for competition since even the smallest differences can permit coexistence of closely related forms -bacteria of the same species with only one allele change coexisted in lab
a behavioral pattern in which young animals postpone breeding and instead help their parents raise offspring
cooperative breeding
A defense against predators in which prey species have a shape or coloration that provides camouflage and allows them to avoid detection.
crypsis
when an animal blends into its environment to avoid detection
crypsis
Constitutive defenses against herbivory are Select one: d. a relatively stable part of a plant's allocation. e. synthesized immediately after the herbivore damages the plant.
d. a relatively stable part of a plant's allocation.
In the Lotka-Volterra predator-prey model, a predator model in the absence of prey would, d. decline exponentially e. the model makes no assumptions about what happens in the absence of prey.
d. decline exponentially
Interference competition involves d. direct aggressive interaction between individuals. e. None of the above.
d. direct aggressive interaction between individuals.
An r-strategist generally Select one: d. has one, large reproductive episode over the course of its life. e. reaches reproductive maturity later in life.
d. has one, large reproductive episode over the course of its life.
1. The Lotka-volterra model of interspecific competition predicts that two species will always coexist when d. intraspecific competition is stronger than interspecific competition for both species. e. the density of both populations is below their carrying capacities.
d. intraspecific competition is stronger than interspecific competition for both species.
In many plant-microbial (fungi or bacteria) mutualisms, a. the plant receives carbon from the microbe and the microbe receives nutrients from the plant. b. the microbe affords some sort of herbivore protection to the plant while the plant provides a source of nutrients to the microbe. c. the interaction can often become parasitic. d. the plant receives nutrients from the microbe and the microbe receives carbon from the plant.
d. the plant receives nutrients from the microbe and the microbe receives carbon from the plant.
If the net reproductive rate (R0) is greater than 1, Select one: a. the population size will stay the same. b. more individuals will migrate to the closest sub-population. c. the population has the potential to decrease. d. the population has the potential to increase. e. fewer individuals will migrate to the closest sub-population.
d. the population has the potential to increase.
A pattern of population fluctuations where the extent to which the population rises and falls in abundance gradually become smaller over time.
damped oscillations
Delays in the effect of population density on population size that can contribute to population fluctuations.
delayed density dependence
Chance events associated with whether individuals survive or reproduce.
demographic stochasticity
Of or referring to a factor that causes birth rates, death rates, or dispersal rates to change as the density of the population changes.
density-dependent
Of or referring to a factor whose effects on birth and death rates are independent of population density.
density-independent
selection favors individuals with one extreme of a heritable phenotypic trait
directional selection
Density-dependent factors
disease, resource competition, predation
selection favors individuals with a phenotype at either extreme over those with intermediate phenotype
disruptive selection
The number of years it takes a population to double in size.
doubling time
Which of the following spatial pattern would be expected if organisms were competing for the same limited resources? Select one: a. Clumped e. Regular
e. Regular
Two species that are able to coexist indefinitely within a given habitat probably have a. a wide niche separation distance and a large region of niche overlap. e. a wide niche separation distance and a small region of niche overlap.
e. a wide niche separation distance and a small region of niche overlap.
The total area of productive ecosystems required to support a population.
ecological footprint
A parasite that lives on the surface of another organism.
ectoparasite
habitat loss and fragmentation
effects: -reduced habitat area -increased fragmentation... increases edge size -increased distance among fragments -reduce genetic variation in isolated populations ex) redcoated woodpecker .. problem is that they compete for breeding vacancies in existing groups and do not form new groups ... because there was a shortage of cavities in the oak trees ex) if an animal needs a certain area to mate but we fragmented it and they cant cross between areas then it has a negative effect on breeding
A parasite that lives inside the body of its host organism.
endoparasite
Erratic or unpredictable changes in the environment.
environmental stochasticity
Lotka-Volterra
equations of competition between 2 species based on logistic curve of population growth
complex species interactions
ex) ant, scale, and plant interaction ants protect the scale insects from predators and parasitoids in exchange for nutriends secreted by scale insects ant-scale interaction: + , + scale-plant interaction: + , - ant-plant interaction: 0, + and - .. no ants mean the scales produce too much honeydew and the plants mold which reduces plants photosynthetic rate
effects of disease on populations
ex) bruncellosis (bacteria) in ungulates transmitted to cattle -causes abortion in female cattle= "contagious abortion" -has a sharp defined threshold for establishment and the proportion of bison infected rises smoothly with pop density =critical threshold ...... does not survive in pops less than 200 but it cant be culled out because that would cause extinction ex) *rabies* ---in class example -there is no cure.. just death -directly transmitted viral infection of the CNS and all mammals are susceptible -most common in small-medium carnivores: foxes, wolves, coyotes, skunks, racoons, bats, domestic dogs -caused by a number of different viruses in the family Rhabdoviridae in the *Lyssavirus* genus -----stop it by culling (not as successful bc high reproduction rates and high dispersal), vaccination (more successful) or a combo of both
A relationship in which one organism benefits by feeding on, and thus directly harming, another.
exploitation
An interaction in which species compete indirectly through their mutual effects on the availability of a shared resource.
exploitation competition
Change in the size of a population of a species with continuous reproduction by a constant proportion at each instant in time.
exponential growth
A constant proportion by which a population of a species with continuous reproduction changes in size at each instant in time; also called the intrinsic rate of increase.
exponential population growth rate (r)
The average number of offspring produced by a female while she is of age x (denoted Fx in a life table).
fecundity
Importance of Proper design & Evaluation of MPAs
figure see lecture 12 p4
Pressures on small and declining population
figure see lecture 12 p4
Maximum Substainable Yield
finding largest fishing mortality rates that can be offset by increased population growth (maximum sustainable yield) see lecture 11 p5
Species-based managment
focus on a single species for conservation
the transfer of alleles between populations, makes populations more similar to one another and can introduce new alleles
gene flow
A specific defensive response that makes particular plant genotypes resistant to particular parasite genotypes.
gene-for-gene interaction
single genetic individual
genet
occurs when chance events determine which alleles are passed from 1 generation to the next. can have negative effects on small populations
genetic drift
genetic makeup of an individual
genotype
Change in the size of a population of a species with discrete reproduction by a constant proportion from one discrete time period to the next.
geometric growth
A constant proportion by which a population of a species with discrete reproduction changes in size from one discrete time period to the next; also called the finite rate of increase.
geometric population growth rate (λ)
goal of harvesting populations
goal is to harvest in a way that is: 1. efficient 2. profitable (for commercial fisheries) 3. sustainable -we do this so we can sustain yield and profit through time.. if you harvest too much one year there will be less next year -need to know the population dynamics of the species being harvested bc we are exerting more mortality on the pop
habitat destruction, degradation, disturbance, fragmentation
habitat adversely affected by human activities: 1. destruction -urban development, food production, harvest of natural resources.. like shrimp nets bc they are dragged on the ocean floor and mess everything up 2. degradation -pollution 3. disturbance -human recreation, ecotourism, ecological research.. dont destroy it but we are affecting it -ecological research on whales could affect their behavior 4. fragmentation -coincident with loss of habitat.. breaking up continuous habitat into smaller isolated patches
The breaking up of once continuous habitat into a complex pattern of spatially isolated habitat patches amid a matrix of human-dominated landscape.
habitat fragmentation
A woody evergreen perennial plant, like a pine tree, likely Select one or more: a. has leaves with a high nitrogen concentration. b. has a rapid growth rate. c. allocates a greater proportion of carbon to growth than survival. Incorrect d. has short-lived leaves with high rates of photosynthesis. e. allocates a larger portion of carbon to survival than to growth Correct f. has many, small, reproductive episodes over the course of its life. Correct g. has a slow growth rate Correct h. has leaves with a high specific leaf area. i. has a type 1 survivorship curve. j. has one, large, reproductive episode over the course of its life. k. has long-lived leaves with low rates of photosynthesis. l. has a type 3 survivorship curve Correct
has a slow growth rate allocates a larger portion of carbon to survival than to growth has a type 3 survivorship curve has long-lived leaves with low rates of photosynthesis. has many, small, reproductive episodes over the course of its life.
An organism that eats the tissues or internal fluids of living plants or algae.
herbivore
R selection (per capita rate of increase)
high population growth rate, unpredictable environments
An organism on or within which a parasite or other symbiont lives.
host
niches / competition (warbler experiment)
how common is competition in nature? (assumed that closely related species on the assumption that taxonomic similarity should promote competition) experiment on 5 species of warbler birds that all are very ecologically similar .... all are insect eaters and about the same size - *coexistence occured* because... these warblers feed in different positions in the canopy, feed in different manners, move in different directions through the trees, and have different nesting dates -explanation of differences can be because of past competition between closely related species *"ghost of competitions past"*............. these descriptive studies are not useful for understanding the importance of competition in natural populations
Mating between related individuals.
inbreeding
In plant-herbivore interactions, a defense against herbivory, such as production of a secondary compound, that is stimulated by herbivore attack.
induced defense
biotic interactions
interactions between and within species important to population dynamics and regulation
An interaction in which species compete directly by performing antagonistic actions that interfere with the ability of their competitors to use a resource that both require, such as food or space.
interference competition
an interaction between 2 species where each is harmed when they both use the same limiting resource
interspecific competition
can occur between individuals of a single species
intraspecific
A metapopulation pattern in which habitat patches located far away from occupied patches are less likely to be colonized than are nearby patches.
isolation by distance
A long-distance dispersal event by which a species colonizes a new geographic region.
jump dispersal
when the animal has already been so exposed to a stimulus that it can't learn to associate a response with it.
latent inhibition
A summary of how survival and reproductive rates in a population vary with the age of individuals; in species for which age is not informative or is difficult to measure, life tables may be based on the size or life history stage of individuals.
life table
Change in the size of a population that is rapid at first, then decreases as the population approaches the carrying capacity of its environment.
logistic growth
Relatively large parasite species, such as arthropods and worms.
macroparasites
global events in which large proportions of earth's species are driven to extinction in a relatively short time
mass extinctions
functional response to predator responses to increases in prey populations
measures for each individual predator how many prey it eats in a given time period -shape of curve relies on range of prey densities 3 types: 1. show a constant consumption of prey with no satiation -density independence 2. logistic reaches saturation -inverse density dependence (allee effect) 3. sigmoidal-ish curve reaches saturation -density dependent (ex) Lynx predating hares --- type 2 response (logistic) -upper plateau is fixed by *handling time*.. time it takes for a predator to catch, kill, and eat a prey -hare abundance increases, lynx numbers increase -example of pred prey oscillation -lynx depend on hares as primary food source so they are food limited -hares are affected by food limitations and predators ---time lag in the numerical response of lynx to hare numbers induces the density cycle of hares
A set of spatially isolated populations linked to one another by dispersal.
metapopulation
exploitative
method of competition where consumption is of a shared resource
interference
method of competition where direct, aggressive interactions are used to defend resource
Parasite species too small to be seen with the naked eye, such as bacteria, protists, and fungi.
microparasites
A defense against predators in which prey species resemble less palatable organisms or physical features of their environment, causing potential predators to mistake them for something less desirable to eat.
mimicry
Rosenzweig-MacArthur model for pred-prey interactions
more realistic model than the Lotka and Volterra model PREY isocline always has a HUMP because as prey numbers increase more predators can be supported but at a diminishing rate -as prey numbers build up they begin to limit their own rate of increase because of food shortage, disease or social interactions -at the hump the number of prey reaches a max and becomes limited - above the hump (to the right of pred max) .. there are higher prey numbers and the curve goes down because the dominant limitation on the prey rate of increase comes from prey intraspecific competition and fewer predators are needed to hold down the prey rate of increase --if predator/prey isoclines cross (eq point) to the right of the hump then it is stable --if isoclines cross (eq point) to the right of the hump then either or both species go extinct (larger oscillations) DEPENDENT ON CHARACTERISTICS OF PREDATOR... rate of increase of pred. depends on density of prey - if the productivity of prey increases the eq density of prey does NOT change -the gain in prey productivity goes to the predators which increase in abundance RATIO DEPENDENT MODEL: fits better -the predation rate depends on the ration of predators to prey rather than just prey on numbers alone ..... predator zero isocline is positive linear
Movement and population dynamics/regulation
movement links populations demographically two examples: metapopulations, source-sink dynamics
sources of new alleles and new combinations of alleles, provide genetic variation on which evolution depends
mutation & recombination
An extreme environmental event such as a flood, severe windstorm, or outbreak of disease that can eliminate or drastically reduce the sizes of populations.
natural catastrophe
The mean number of offspring produced by an individual in a population during its lifetime.
net reproductive rate (R0)
competition in natural populations
niche overlap/competition -species can compete if their niches overlap should NOT assume that it is always occurring in natural populations bc it may be rare in some populations if the environmental fluctuations are high
Grimes theory of plant strategies
no one combination or one strategy was possible of factors that affect plant growth and reproduction possible factors: 1. light, water, temperate stress, other physical/chem limitation 2. disturbances, grazing, diseases, storms, erosion, etc IF: 1. *intensity of disturbance AND intensity of stress is LOW* = competitive strategy (K-selection) 2. *intensity of disturbance is LOW and intensity of stress is HIGH* = stress-tolerant strategy 3. *intensity of disturbance AND intensity of stress is HIGH* = no strategy possible 4. *intensity of disturbance is HIGH and intensity of stress is LOW* =ruderal (weed or r-selection) strategy
indirect interactions and apparent competition
not all competitive interactions are directly between 2 competing species COMPETITION 1. *interference* - direct interaction, allelopathy 2. *exploitation* - indirect interaction via shared resource... 2 plants indirectly interact negatively and the resource directly interacts with the plants positively and the plant directly interact with the resource negataively APPARENT COMPETITION 3. *indirect interaction* VIA shared enemy ... 2 plants interact indirectly and each plant interacts with the enemy in a positive way and the enemy directly interacts with plants negatively 4. *indirect interaction* VIA other species on same trophic level .....plant 1 and 2 directly interact , plant 2 and 3 directly interact and plant 1 and 3 indirectly interact
competition exclusion
one species eliminated
An organism that lives in or on a host organism and feeds on its tissues or body fluids.
parasite
An insect that lays one or a few eggs on or in a host organism (itself usually an insect), which the resulting larvae remain with, eat, and almost always kill.
parasitoid
A parasite that causes disease.
pathogen
Per capita rate of population growth
per capita rate of population growth decreases as population size increases and vice versa
A feature of the environment that affects organism function and population growth rates but is not consumed or depleted.
physical factor
Feeny's plant apparency theory
plants can be divided into 2 classes: 1. *"apparent"* plants -- those that are found easy by herbivores -evolve chemical defenses -long lived -uses quantitative defenses 2. *"unapparent"* plants -- hard for herbivores to find bc they are small or rare or short lived -uses qualitative defenses that are poisons to protect from general herbivores that have evolved detoxification mechanisms -the type of defense a plant needs depends on how easily the plant is found by the herbivore
A pattern of population fluctuations in which alternating periods of high and low abundance occur after nearly constant intervals of time.
population cycles
the ways in which populations change in abundance over time
population dynamics
The most common pattern of population growth, in which population size rises and falls over time.
population fluctuations
An extremely rapid increase in the number of individuals in a population.
population outbreak
A pattern of population growth in which one or more density-dependent factors increase population size when numbers are low and decrease population size when numbers are high.
population regulation
An organism that kills and eats other organisms, referred to as its prey.
predator
allee effect
predicted (in caribou's) that as population density falls, the population growth rate would go up ...... the OPPOSITE happened -allee effect was caused by predation by wolves ex) wolf populations are primarily limited by their primary prey (moose) and they treat caribou as their 2nd prey in their diet --woodland caribou suffer *apparent competition* (both directly/positively affect the wolf, the wolf directly/negatively effects both prey, and both prey are indirectly competing) with moose
An organism eaten by a predator.
prey
Lotka and Volterra predator-prey model
prey = logistic growth - pred prey encounter rate (NP) times attack efficiency (c) -----prey N increases logistically in the absence of predator P predators = cNP - rpP -----predators P grow when prey N is around according to the attack efficiency c.... but decrease exponentially without prey PREY: - have a zero rate (linear decrease).. prey increase below isocline and decrease above isocline PRED: - have a vertical isocline ... increase if prey population is greater than isocline... and predators decrease if less than isocline BOTH TOGETHER: ... now divided into 4 regions 1. under prey isocline and left of pred isocline = decrease pred. and increase prey 2. under prey isocline and right of pred isocline = increase pred and prey 3. above prey isocline and left of pred isocline = increase pred decrease prey 4. under prey isocline and right of pred = decrease both --there is an *oscillation spiral effect* ...... STABLE OSCILLATION approaches an equilibrium point where the lines cross each other ...... look at it through time and we see a *time lag* between predators and prey in nature OVERALL: range of dynamic behavior - limit cycle oscillations - stable dampening oscillations toward equilibrium - unstable oscillations away from equilibrium.. depends on parameters.. species could go extinct - stability from other limiting/regulating factors.. like resource limitation for the prey - simplistic due to assumptions - framework adaptable for relaxing various assumptions (Rosenweig-McArthur graphical model).. better match up natural systems
potentially independent members of a genet. physiological individual of asexually reproducing species.
ramet
an estimate of population size based on data that are related in an unknown way to the absolute population size
relative population size
competitive release
removal of one species allows expansion of other's range;ex: competition in rodents- one eats grains, one eats insects
A tendency for high rates of immigration to protect a population from extinction.
rescue effect
A feature of the environment that is required for growth, survival, or reproduction and which can be consumed or otherwise used to the point of depletion.
resource
The use of limiting resources by different species in a community in different ways.
resource partitioning
impacts of introduced species
responsible for about 40% historic extinctions -early explorers introduced many new species.. this led to high rates of extinctions on islands -islands have high endemism -reduced abundance and diversity of native organisms -introduced species often are superior competitors for resources -or may be very efficient predators ex) superior competitor (alga Caulerpa taxifolia) -native to the indian ocean -cultured for aquaria.. bred to withstand cold water -commonly introduced by dumping aquaria -produces strong toxin -reproduces by fragmentation -grows very rapidly -outcompetes plants and algae for light and space.. mediterranean sea has loss of fish and grass -impacts biodiversity and population abundance ex) red fox in australia ex) nile perch ate all the cichlids in lake victoria
A chemical compound in plants not used directly in growth, and often used in such functions as defense against herbivores or protection from harmful radiation.
secondary compound
Population regulation in plants
see lecture 11 p 2
Detecting density dependence
see lecture 11 p1
Competition in rodents
see lecture 8 page 5
Direct and indirect effects of competition
see lecture 8 page 6
Evidence for competition
see table 10.1 chapter 10
herbivory
simply organisms eating other plants -sometimes lethal, often non-lethal -benefits consumer, harms plants ---herbivore does NOT kill plants but only eats parts of it -plants cannot move so escape from herbivores can be achieved by clever adaptations
A predator that hunts by remaining in one place and attacking prey that move within striking distance.
sit-and-wait predator
observers learn specific behaviors from models (also called observational learning)
social learning
the process by which one species splits into 2 or more species. requires the evolution of reproductive barriers between populations and can lead to long-term patterns of evolution
speciation
Niche overlap
species can compete if their niches overlap
What happens when have two species interaction? What happens to their population sizes?
species interactions depends entirely on the environment they occur in. CONTEXT DEPENDENT.
selection that favors individuals with an intermediate phenotype
stabilizing selection
A population age structure that does not change from one year to the next.
stable age distribution
A pattern of population fluctuations in which abundance cycles indefinitely.
stable limit cycle
A life table that records the survival and reproduction of individuals of different ages during a single time period.
static life table
case study : western australian spiny lobster
success story!! -first fishery to receive Marine Stewardship Council certification -understood life stages Key to success: -population monitoring (especially recruitment) -strong harvest control rules (limited entry, adjustable effort.. number of traps) -community support
The proportion of individuals of age x that survive to be age x + 1 (denoted Sx in a life table).
survival rate
The proportion of individuals that survive from birth (age 0) to age x (denoted lx in a life table).
survivorship
An organism that lives in or on an organism of another species, referred to as its host; a symbiont is the smaller member of a symbiosis.
symbiont
match/mismatch hypothesis
the critical period postulates that early in the life of most fishes tehre is a short time period of max sensitivity to environmental factors -assumed that oceanographic effects (currents, winds, temp) on food availability for newly hatched fry are critical in determining year-class size in fished and that either temporal or spatial mismatching can produce recruitment failure
fundamental niche
the ecological space occupied by a species in the absence of competition and other biotic interaction from other species --abstract, hard to measure ... can be measured in the lab --when species deliberately or accidentally are introduced to new regions, they often leave behind their competitors and predators, so that they occupy more of their fundamental niche
stock
the harvest-able part of the population being exploited
realized niche
the observed resource use of a species in the presence of competition and other biotic interactions -set of actual factors being observed.. competition may limit a species from filling thier "actual" niche
maximum sustained yield (MSY)
the predicted yield that can be taken from a population without the resource collapsing in the short or long term on a logistic growth graph -the highest yield is when the slope is greatest bc we are adding indiv faster.. so this is a good number to catch growth + recruitment = natural mortality + yield -max yield achieved from pops at less than max density assumptions: 1. steady growth, recruitment, natural mortality 2. no age structure 3. no time lags 4. all indiv are identical ex) El Nino --- caused the collapse of the Peruvian anchovy fishery (example of *overfishing*) -the recruitment was very low and removed so much biomass that it collapsed -model not being met -caused by *environmental variability*
r-selection
the type of natural selection experienced by populations that are undergoing rapid population increase in a relatively empty environment 1. small sized organisms 2. many small reproductive units (seeds, spores) 3. little energy used per reproductive unit 4. early maturity 5. short expectation of life 6. single reproductive episode (semelparous) 7. type 3 survival curve (highest mortality in early life)
The minimum number of individuals susceptible to a disease that must be present in a population for the disease to become established and spread.
threshold density
What is the goal of ecological restoration?
to restore habitats that have been degraded or destroyed. Can also create new habitats
plant replacement series experiments (*facilitation*)
to study the effect of one plant species on a competing species --can be viewed as an array of plots with different combinations of the two species -the density of plants is kept constant and only the percentage composition is changed .. variables are the yield of each species and the combined yield of both species .. yield was determined by competition between the two species and competition among the individuals of the same species ----mixture of 2 species had higher yield than the species alone ===> phenomenon called *facilitation* -plant interactions have both negative and positive effects on each other in NATURAL ecosystems
Limitation of the abundance of a population by consumers.
top-down control
Gauses's Paramecium experiments
two species, grown alone and also together
A survivorship curve in which newborns, juveniles, and young adults all have high survival rates and death rates do not begin to increase greatly until old age.
type I survivorship curve
A survivorship curve in which individuals experience a constant chance of surviving from one age to the next throughout their lives.
type II survivorship curve
A survivorship curve in which individuals die at very high rates when they are young, but those that reach adulthood survive well later in life. most common.
type III survivorship curve
A defense against predators in which prey species that contain powerful toxins advertise those toxins with bright coloration; also called aposematic coloration.
warning coloration
tragedy of the commons
when a resource is held by everyone the best policy for each individual is to harvest as much as possible -if you dont catch it then someone else will (huge reason why fisheries collapse)
Facultative Mutualism
when a species can live without its mutualistic partner
Obligate Mutualism
when a species is dependent on a mutualistic relationship
competition
when organisms reduce the availability of a shared resource by use or defense -resource is often limited -animals do not need to see or hear their competitors -many or most of the organisms that an animal sees or hears will not be its competitors (like oxygen is something all animals use but is not a source of competition) -competition in plants usually occurs among individuals rooted in position and therefore differs from competition among mobile animals (spacing of indiv is important) -*intraspecific*: between members of the same species -*interspecific*: between 2 or more different species (Lotka-Volterra competition model).. species have to overlap in resource use and that competition over these resources has negative effects ex) *exploitative competition* *interference competition*
competitive exclusion principle
when there is no differentiation between the niches of two competing species;ex: paracium and Birch's grains beetle
Lines derived from the Lotka-Volterra competition model marking the conditions under which a population does not increase or decrease in size.
zero population growth isoclines
density dependence in dynamic pool models (stock recruit curves)
*stock recruit curves* -fished populations are still subject to population regulation -for most fishes this occurs as density-dependent recruitment (entry of young into the stock, the portion of the pop that is fished) -ecologists think that natural mortality is independent of density -fecundity does decline at high pop density in some fishes -need to have estimates of recruitment at very low stocks -if recruitment is highly variable then it is vulnerable to *overfishing* assumptions -constant environment -no spatial heterogeneity -assume stock is one pop not 2 interacting 2 TYPES OF CURVES!!!!!!!!!!! 1. *Beverton-Holt model* (long lived species) -assumes that there is no falloff in recruitment at high pop levels and gives rise to a stable pop size -curve rises to an asymptote at very high stock density -max recruitment is always at max stock size 2. *Ricker model* (short lived species) -the recruitment curve may peak below eq density so that there would be a max in recruitment at intermediate stock sizes -closely related to the discrete generation analogs of the logistic eq in which population growth may show *large oscillations* about carrying capacity
Predator Responses to Prey Population Functional Response: Type 2
- Density -dependent - Slope is highest at low prey densities -Predators become satiated -Asyptote fixed by handling time (time to catch, kill, and eat prey)
Predator Responses to Prey Population Functional Response: Type 1
- Linear - Density - independent -slope is constant -E.g. Bivalves
Limitations of determining species interaction types
- Time scale for measuring effects not identified - Does not describe many indirect interactions
minimal viable population MVP
- the acceptable pop size that ensures some acceptable probability of persisting for a specified time .. drop below this size and it will go extinct estimating MVP: 1. genetic approach -*effective population size* (the number of breeding individuals in an idealized pop that would maintain the existing genetic variability.. typically much less than observed pop size) -*rule of thumb: 50/500 rule*... effective population of 50 to avoid inbreeding and 500 to avoid genetic drift ..... does not apply to species that are subject to environmental variability and different breeding systems 2. demographic approach -*population variability analysis (PVA)*.. population projection modeling.. assess extinction risk given demographic rates ex) woodpecker.. know avg # of chicks in brood and we know how size might chance due to rain and food in a season and we know how mortality might vary ... run in comp and see how many go extinct -*VORTEX* .. demands demographic data on sex ratios, age at maturity of each sex, etc.
Minimal Viable Population
-(MVP) the population size that ensures some acceptable probability of persisting for a specified time
Lotka-Volterra Equations for Competition
-(for species 1): dN1/dt =r1N1*[(K1-N1-aN2)/K1] -(for species 2): dN2/dt = r2N2*[(K2-N2-BN1)/K2]
classification of species interactions
-*competition*: two species use the same limited resource or seek that resource to the detriment of both -*predation*: one animal species eats all or part of a second animal species -*herbivory*: one animal species eats part or all of a plant species -*parasitism*: two species live in a physically close, obligatory association in which the parasite depends metabolically on the host -*disease*: an association between a phathogenic microorganism and a host species in which the host suffers physiologically -*mutualism facilitation*: two species live in close association with one another to the benefit of both interactions between pops can be classified on the basis of either the mechanism of the interaction or the effects of the interaction
spatial ecology of marine species
-*metapopulation*-- a network of interconnected isolated subpopulations -*connectivity*-- how "connected" subpopulations are to each other via dispersal of individuals... usually larvae but sometimes adults depending on patch spacing and adult behavior -adult habitat is often patchily distributed in space -at various spatial scales patches become relatively isolated from each other
Fundamental Niche
-ALL environmental factors that contribute to species growth, survival and reproduction -a larger space where species are able to survive.
What are the three major types of "classic studies used by Gause to examine predator-prey dynamics in the lab?
-All 3 experiments used Paramecium caudatum (prey) and Didinium nasutum (predator) -Type 1: Predator/prey interaction let to the extinction of both. Predators exterminated prey and then died of starvation -Type 2: Introduced sediment which served as refuge for the prey. Predator eliminated prey only form the clear-fluid medium and then starved to death. Prey hiding in the sediment emerged to increase in numbers. System reached stable equilibrium -Type 3: Introduced immigration into the experimental setup. Every third day he added one Paramecium and one Didinium. Stable oscillations in predator and prey numbers.
Keystone Inducer
-An influential predator that elict defensive responses in multiple prey species thereby producing community-wide cascades. Which may have disproportionate effects on its community, even though its abundance may be relatively low. -Ex: European green crab (Carcinus maenus), Pisaster (sea stars) & maybe Tiger sharks
Facilitation
-Any species interaction where one species benefits and another is unharmed (or benefited) -Ex: mutualism & Commensalism
How did abiotic factors influence outcomes of competiton between the beetles Rhisopertha & Calandra? How is this relevant to climate change?
-At 14% moisture & 29.1℃, Calandra eliminated Rhisopertha, but when the temp. changed to 32.3℃, Rhisopertha eliminated Calandra. -This shows that the behavior of a species can be altered by temperature. Leading to the conclusion that as climate change occurs species change and allows the possibility for extinction.
What types of organisms are mostly studied for marine TMIIs? What is the typical focus of these studies?
-Benthic Macro Organisms. ex: Green Crabs - Snails - seaweed -The focus on these studies is to determine the behavioral changes the crabs can apply on snails through chemical cues, which then changes snail's interactions with seaweed.
Population Interactions
-Biotic interactions between and within species important to population dynamics and regulation -Classification of interactions: does the population "benefit" or is it "harmed"?
What are the outcomes of competition?
-Both species 1 & 2 go extinct -Coexistence.
Trophic interactions
-Carnivores--direct -Herbivores--direct -Producers--indirect to carnivores (trophic cascade see lecture 9
Why might lab studies on TMIIs be ecologically unrealistic?
-Close proximity of predator to prey, may allow cues to build up to unreasonably higher levels than may be occurring in nature.
What conditions allow geometric growth?
-Colonizers in unoccupied, suitable habitat -Populations "freed" from predators, diseases, competitors
Populations benefit or are harmed by several interactions:
-Competition: influences distribution and abundance (-, -) -Predation: predation also includes: herbivory, disease (pathogens) and parasitism (+,-) -Mutualism (+,-)
Nutritional Mutualisms
-Complementary Nutritional resources -Ex: Plant Mycorrhizae
Predator Responses to Prey Population Functional Response: Type 3
-Density - dependent - Slope is steepest at intermediate prey density - Prey switches behavior (learning) -Predators get better at capturing prey -Predators become satiated with prey - Only case where predators can regulate prey population
Population Interaction: Predation
-Effects on abundance -Community structure (community-interactions) (assemblage--not necessarily) -mechanism of natural selection
Problems with MSY
-Environmental variation: may be impossible to obtain reliable estimate of MSY -MSY only know if you go past it (overexploitation)
What is trait Cascade? How does this differ from most studies of TMIIs?
-Example:Fish scares shrimp, shrimp eat less, inducible chemical defenses are reduced in seaweed. -TMIIs typically alter the abundance of basal prey. They may also alter traits of basal prey.
Trophic Mutualisms
-Exchange food resources -Ex: Honey Guides and Humans
Huffaker's Experiments with Mites
-Experiments to obtain persistence of predator and prey populations without immigration -two species of mites: one fed on oranges the other one a predator (importance of environmental heterogeneity) 252-orange system, petroleum jelly barriers, wooden pegs see figure 11.8 & 11.9 p195, 196.
How to estimate MVP with Effective Population Size?
-Genetic approach (avoiding inbreeding and genetic drift) -Maintain an Effective Population of : 50 to avoid inbreeding & 500 to avoid genetic drift
Issues in designing marine protected areas
-How big? (Sustain population; ecosystem function) -How many? (Single large or several small; SLOSS) -Where? (Location, habitat) -What species? (single or multiple species) -What activities? (Fishing, research, etc)
Some amphipods sequester chemical defenses from pteropds. How do they do this? Why?
-How: Amphipods attach the pterodods to their backs and swim around with them (abduction) -Why: for chemical defense against predation
Adaptive management of MPAs
-Identify hypothesis relevant to management decisions (e.g., design criterion: reserve size influences sustainability) -Design reserves with treatment levels and identify appropriate response variable(s) -Monitor response and evaluate -Use evaluation to optimize design of future reserves
Competitive Exclusion Principle
-If there is no differentiation between the niches of two competing species, then one species will eliminate or exclude the other -when differentiation of niches is allowed by habitat, coexistence of competitors is possible
Assumptions using MSY
-Ignores age, growth survival, reproduction -Treats environment as unvarying
How is the Red Queen Hypothesis connected to the Red Queen's Race that Alice engages in?
-In the Red Queens Race, both the Queen and Alice are both running at the same rate; Alice is attempting to escape the Queen who is trying to capture her. Diseases and parasites are attempting to "catch" their host, while the hosts are attempting to "escape".
Which mode of competition has a winner?
-Interference competition generally has a winner and loser. -With exploitative competition, once the resource is depleted all competitors lose.
Empirical data are often a poor fit
-Large variation around stock-recruitment relationship -Often poor fits to empirical data
Converting between species
-Needs to show that species are equal to one another and deals with how EFFECTIVE they are: body size, etc.
How might ocean acidification affect populations?
-Ocean acidification weakens/removes inducible responses. At a lower pH we see organismis having a hard time detecting/reacting to chemical cues. -ex: on a different pH, the clown fish will no longer be able to detect predators and may even be attracted to it. As the clown fish avoids inbreeding and will no longer be able to recognize the smell of related individuals. They wil also no longer be able to find the sea anename host.
Defensive Mutualisms
-One species protects another in reurn for a "reward" -ex: Acacias & Ants
Specialist Mutualisms
-Only 2 species can participate -ex: Jazen's Ant-acacia system
Why might apparent competition be confused with actual competition?
-Organisms of different species may interact directly or indirectly. Indirect effects can occur because the two species have no interactions with each other, but interact only through a third species or shared resource. Indirect effects could produce apparent competition. -example: An increase in density in "high Red" area can draw predators into the area. It appears that the presence of excess Red Snails is adversely affecting the Green Snail density, but it is the predator that is actually affecting it. (apparent competition.
What is the smallest population that can persist?
-Population genetics: "effective population size" -50 individuals to prevent inbreeding -500 individuals to prevent genetic drift -Actual populations would have to be 3-10 times larger and some estimates are in the thousands
Predator Satiation (Escape in number)
-Predator satiation: reducing individual probability of being eaten by producing high density -Examples: 1. "masting" in seed-producing plants; 2. periodical cicadas
Conservation applications of MPAs
-Protect species and habitat (i.e. ecosystem approach) -Create "pristine" systems as baseline to distinguish localized anthropogenic from natural variation -Protect spawning stock for larval replenishment of populations inside and outside reserves
Limits to Population Growth
-Resources: necessary resources are limited, which prevents indefinite geometric growth; the role of intranspecific competition. -Growth in the "real world": logistic growth -Other factors are also important: disease and parasites; predators; inter-specific competition
What type of habitat is the restoration project at San Dieguito Laggoon trying to restore?What facility is this a restoration a mitigation project?
-Salt Marsh -San Onofre Nuclear Plant
What factors should promote local adaptation?
-Scale of dispersal is less than scale of selective gradient -High dispersal wipes out adaptation patterns, direct development -when a baby is bon or hatched into an environment & stays there, it promotes adaptation
Energetic Mutualisms
-Share Energetic Resources -Ex: Corals & Bacteria
What organism is currently attacking trees (especially Willows in the Tijuana River Valley)? What does the organism do to the trees?
-Shot-hole borer beetle -Bores into and Kills Willow Trees - Weakens property of Tree and makes it susceptible to breaking.
Conservation Ecology is particularly concerned with?
-Small populations -Declining populations -Why species go extinct
What are the risks that small populations face & how does variability contribute to the risks?
-Small populations are more likely to start the "extinction vortex"
According to Trussel et al. 2008, how do predator avoidance behaviors of snails compare between mussel and barnacle habitats?
-Snails respond more strongly to crab cues than they do mussel cues. This is because the barnacles are low line, they do not have a lot of relief, and they don't have spaces to crawl into. If you detect a predator there you better haul ass, but if your in a mussel habitat, they can hide easily, due to the elevation of where these barnacles are established
How did avoidance behaviors compare for intertidal snails when given seaweeds from Exposed vs Protected Shores as habitats?
-Snails would risk exposure if given the exposed shore seaweeds because it is "yummier", therefore worth the risk
Resources
-Something that is consumed by organism. -Abundance reduced by consumption -used for growth, maintenance, or reproduction -reduction in resources reduces population growth -important when limited
How might predators influence growth efficiency?
-Stress associated with predation risk may limit growth efficiency -In the presence of the predator, the green crab, these snails growth efficiency is actually suppressed. It's not just that these snails are eating less, but of the individual barnacle ingested, the snail is less able to convert the nutrients to their own tissue.
Compare the densovirus loads of asymptomatic ans sympotmatic sea stars.
-Symptomatic sea stars have a higher SSaDV loads -injecting stars w/virus-sized fraction decreased proportion asymptomatic. -Viral challenge experiment increased SSdDV abundance: 2nd challenge too material from 1st challenge individual
Red Queen Hypothesis to the evolution of sex?
-The Red Queen Hypothesis is the coevolution of parasites and their hosts, or predators and their prey, in which improvements in one of the species is countered by improvements in the partner species. -This drives evolution of sex, because it leads to an evolutionary arms race; neither species gains an advantage but they continually adapt and fitness is altered accordingly.
Character Displacement
-The divergence of a species due to being too similar to another species in the same habitat. -This assumes that species too similar to one another could not coexist without interspecific competition . -Divergence allows species to occupy different niches, and thus reduce competition.
Why might mutualisms between plants and Mycorrhizae depend upon resource availability?
-The plant and Mycorrhizae form an association with plant roots so the sugars that its producing via photosynthate may be consumed. In return the Mycorrhizae provide the plant access to these sugars. -No nutrients = No mutualism -example of context dependent
Modern human population trends
-Total fertility rate (number of children an avg woman has). -Life expectancy is increasing. -Humans can't support multiple children financially.
What type & modes of competition are there?
-Types: Intraspececific & Interspeceific -Modes: Interference & Exploitative
Generalist Mutualisms
-Variety of suitable partners -ex: Pollinator mutualisms
Which type of TMIIs is most commonly observed in the field?
-When we look through the literature, over 1/2 the examples of herbivore competitive interactions follow this example: -By herbivore A eating the food source, herbivore A makes the food source uneditable (indirectly) for herbivore B, via trait mediated interactions. (ex: chemicals production)
Trait Mediated Indirect Interactions
-a first species affects a trait of a second species, which in turn affects the interactions of the second species and a third species. -important because a single predator can affect more prey on a per capita basis. -Involve inducible responses which can behavioral, morpholgical or chemical
Lotka-Volterra equations *must review graphs on pg 166*
-a interspecific competition model -the set of equations that describe competition between organisms for *food or space* -----measures population sizes -based on the logistic growth model -if species 2 can use less resources than species 1 and can have more indiv then we have to add a variable to the logistic model equation for species 1 (alpha N2) to that there is an equivalent number of species 1 to species 2 -*isocline*: the diagonal line formed when the 2 species pop is graphed.. when all points are at equilibrium -equilibrium when diagonal curves cross each other *-no mechanism by which one species excludes the other*
Which equation do use to covert between species?
-aN2 = # of species 2 in units of species 1 -BN1 = # of species 1 in units of species 2
diseases
-an interaction in which a disease organism lives on or within a host plant or animal to the benefit of the disease agent and detrimental to the host typically small, unicellular organisms -viruses, bacterial infections, pathogentic fungi, prions ="microparasites"
parasites
-an organism that grows, feeds, or is sheltered on or in a different organism while having a negative impact on the host -large, multicellular organisms = "macroparasites" ex) tapeworm -ectoparasites : live on outside of host organism -endoparasites: lives internally often have multiple hosts
dispersive mutualisms
-animals transporting pollen or seeds in exchange for food variety of evolutionary adaptions --plants: colored flowres, nectar, odor, flower structures/morphology, flowering times -animals: flight, structural adaptations to access nectar ex) fruitvores dispersing seeds
overfished
-biomass of stock is below some pre-determined critical minimum value -when pops dip below thresholds
mutualisms
-both interacting species benefit -usually involved complementary functions (making resources more available for the other species) -*obligatory mutualism*- interaction required for survival of one or both species -*faculatative mutualism*- not required for survival functions: -trophic (sharing food resources) -dispersive (spreading seeds) -defensive (protection from consumers)
Evolutionary evidence
-character displacement: change in morphology; evolution towards niche divergence because of competition -competition reduces individual fitness -natural selection will favor traits that reduce competition
Lotka-Volterra Model POINTS
-characterized by oscillations in the prey and predator populations with the predator's peak lagging behind the prey's peak -Predator population HIGH, Prey population DECREASE. if prey LOW, predator pop will DECREASE -As predator decreases, prey INCREASE -Prey populations HIGH, Predator populations INCREASE.
principles for successful marine reserves
-clearly defined goals -understanding of natural history of the system -scientific guidance on design and principles and evaluation of options, both ecologically and economically -stakeholder/community involvement and support -effective enforcement -effective monitoring and evaluation post implementation
trophic mutualisms
-complementary modes of nutrition ex) lichens -alga provides sugars from photosynthesis -fungus provided access to nutrients required for photosynthesis
optimal defense hypothesis
-defenses are costly to fitness (but so is herbivory) so plants should allocate defenses in a way that maximizes fitness -resources to produce defense compounds may be limited -tradeoff between energy devoted to defense vs growth/reproduction... inducible defenses a way to mitigate this trade off assumptions: -there is genetic variation in plants for secondary compounds -that herbivory is the primary selective agent for these secondary compounds -these defenses reduce herbivory
virulence
-degree or ability of a pathogenic organism to cause a disease -depends of the intensity of the disease it causes and is measured by host mortality *sublethal effects*-- any effects that reduce well being but do not cause death ---more important to plant and animals in ecological setting bc it interactions with competition and predation in affecting population dynamics
herbivore adaptations
-depelop adaptations to plant defenses -behavioral and physiological ex) oak trees and larvae -larvae are laid in tree in may when the leaves are young and then they stop feeding in early june -this is because the leaves produce more tannins (secondary plant substance) from spring to fall and the amount of protein decreases from spring to summer
Declining populations
-detecting and halting population declines -deterministic extinctions (essential resources are removed or something lethal is introduced
Competition can lead to
-exclusion of one species -coexistence of both species
Huffaker's pred/prey experiments with Mites
-experiments to obtain persistence of predator and prey populations WITHOUT immigration -claimed Gause used too simple of a mircoorganism so he used Eotetranychus sexmanculatus (prey) and Typhlodromus occidentatis (predator) ... they prey mite infests oranges so he used this for the experiment 1. predator introduced onto a single prey infested orange - it eliminated the prey and then it was completely eliminated bc starvation 2. 40 oranges and 20 were covered with paper -limited available feeding area for prey so prey increased and then predator increased and then both went extinction -could NOT recreate oscillations 3. 252 orange system.. petroleum jelly barriers and wooden pegs (prey could hop/skip on pegs) -all were limitations and got oscillations!! -importance of *spatial heterogeneity* ... could not have a uniform environment and need a variety of patches that are both good and bad for predator and prey a like
resource availability hypothesis (grow rate hypothesis)
-faster growing plants can replace tissue/leaves lost to herbivory faster, so they have lower investment in defenses -slower growing plants invest proportionally more energy in each leaf, so they should be more defended .. have more defensive chemicals -this hypothesis adds to plant-herbivore interactions bc the growth rates in plants are strongly affected by available resources .. like nitrogen, water, etc
declining populations
-focuses on the ways of detecting, diagnosing, and halting a population decline -viewed in demographic terms as a population in trouble -external agent has to be identified as cause of decline -current size of pop is NOT important ... the downward trend is what is important conserve declining pops and preventing them from becoming too small: -figure out what is causing decline -remove/mitigate specific causes -done on a case by case basis (reason why its hard to have a general theory) ex) sea turtles -all species listed as either endangered or threatened -biggest effect on pop growth rate by reducing large juvenile mortality .. reduce bycatch mortality with turtle excluder devices ex) prairie chicken --- habitat fragmentation led to less eggs hatched and less genetic diversity and small pops... then went into extinction vortex then they were translocated and it worked out
predation in natural systems
-greatest advantage of field studies relate to scale bc some things are too large to measure in the lab.... also happen over a longer period of time so they reveal more complexity of systems -sometimes see cyclical oscillations as predicted by models ex) lynx eats the hares -cannot study the effects of predation by counting the numbers of prey killed.. you must determine factors that condition predation, the factors that make certain individuals vulnerable to predation while others are protected.... a lot of prey are hunted bc old age, etc -in some but not all cases, the abundance of predators does influence the abundance of their prey in field populations can be caused by human introduction of predators ex) sea lamprey feed on trout and kill them when they spawn and prey pop went to zero
L-V Assumptions
-growth of the prey population is limited only by predation -predator is a specialist that only persists of the prey population in present -individual predators can consume infinite prey -predators and prey encounter each other randomly in a homogeneous environment
Putting the "brakes" on population growth
-how do we put "brakes" into our growth model? -carrying capacity: a given environment can only support some maximum number of individuals in a given population -K=carrying capacity -incorporate K into the geometric model
Logistic Model
-how is maximum yield obtained? recruitment + growth = natural mortality + fishing yield
multispecies fisheries
-impossible to harvest at max sustained yield fora ll species so they are difficult to manage -one fish that is being overharvested can be caught in the same net as a species who is underharvested ex) salmon... operates on mixtures of stocks from different river systems and different spawning areas within one system.. the result is that less productive salmon stocks are overfished and the more productive stocks are not fully utilized
Characteristics of competition
-individuals are inherently equivalent in competitive ability (intraspacific competition) -competition often asymmetrical between species (one species is dominant) -effects of competition are necessarily density-dependent
Method of competition (types of competition)
-interference: direct aggressive interactions used to defend resource -exploitative: consumption of a shared resource who competes? -intraspecific: within species -interspecific: between species
marine population ecology
-marine species have a *bipartite* life cycle -adults are relatively sedentary -larvae are planktonic (drift in water column with current) -*pelagic larval duration (PLD)*... time from when larvae are born until they settle back to adult habitat.. really variable
case study : whaling
-max sustained yield is around 80% unfished biomass... does not follow the sigmoidal curve which would be around 50% -most data is fishery dependent Problem: -life history makes them extremely susceptible to overharvest bc they are long lived and low reprod rates -serial depletion of species.. went from one species to the next -economic future discount rate make sustainable harvest over time less profitable than driving the pops extinct now
Tilman's model *look at graphs on pg 169*
-mechanistic model based on consumption rate of shared resources.. *community level predictions about species diversity and succession* -2 key parameters 1. the boundary between pop growth and decline is the zero growth isocline of this species 2. the rate of consumption of the two essential resources ... each species will consume resources at different rates --if there is an other lap of the isoclcines there is an equilibrium point... need to determine if it is unstable or stable ........ do this by knowing the rate of supply of the limiting resources to the populations and the rates of consumption of these resources by each species
evolution of competitive ability
-natural selection should favor traits that either: 1. reduce competition -however, avoiding competition doesnt work because competition can be caused by a web of species.. just because you reduce competition with species B doesnt mean you eliminate it with species C 2. enhance competitive ability -one element of the more general problem of the evolution of life history strategies -constrained by life history and environmental stability UNSTABLE ENVIRONMENTS ANALYZED USING: in logistic curve model 1. *r-selection* (r = rate of increase) -in unstable habitats and remain on the rising portion of the curve for most of the year 2. *K-selection* (K = saturation density) -in stable environments organisms exists near K
the problem of coexistence
-not predicted to occur very often in lab ... but it is abundant in nature WHY? 1. unstable, non-equilibrium conditions (environmental instability) -*paradox of the plankton*... before competitive displacement could have time to occur, seasonal changes would occur.... NOT an exception to the principle of competitive exclusion because they are a nonequilibrium of competing species (still competing) 2. no resource competition 3. fluctuations in the environment that reverse the direction of competitive exclusion before extinction (ex.. temp changes)
exploitative competition
-occurs when a number of organisms (of the same or different species) utilize common resources that are in short supply -*all individuals are equally affected* no winners/losers INDIRECT interaction mediated by a shared resource
Characterisitcs of Competition
-often asymmetrical between species -a given level of resources can support different number of species A and species B -one species is dominant -depend son population density
defensive mutualisms
-one species protects another in return for a "reward" ex) ants and acacias acacias: ---susceptible to herbivores ---produce Beltian bodies and nectarines ants: --defend acacias from herbivores by attacking them --feed on nectarines and Beltian bodies ***** the acacias really do benefit from the ants bc when the ants were removed the plants weighed less than 1/10 as much as they did and had 1/2 the leaves and 1/3 the number of swollen thorns
disease and its effects on mortality
-parasite may alter host behavior.. zombies! ex) eustrongylides life cycle -adult eustrongylides mate and reproduce--> egg --> larvated egg---> egg ingested by oligochaete worm --> oligachaete ingested by mosquito fish --> eaten bu the adult eustronglyides ex) 60% of seals in baltic sea died from an epizootic virus -caused females to abort babies -similar to canine distemper -within 2 weeks seals typically got pneumonia with secondary bacterial and viral infections -more common in males than females although both were infected -there are seals who survive and reproduce but then the new births are susceptible to the virus again and the chain continues ex) west nile virus-- virus can amplify in birds and be transmitted by mosquitos but humans cannot amplify the virus -some cows recovered to get genetic resistance -key lies in feeding behavior of mosquitos from birds to humans at a certain time of year
small population paradigm
-population consequences of rareness and the abilities of small pops do deal with smallness -many species are "rare" but not all rare species are at risk of extinction -deals with questions arising from population genetics and demographic models of extinction -*extinction vortex* -- small pops risk positive feedback loops of inbreeding depression, genetic drift, and chance demographic events some extinctions occur by chance alone: -demographic stochasticity [Pext = (d/b)^No]... if the birth and death rate are equal than it has 100% chance of going extinct.. critical when pops 30-50 or less -genetic stochasticity.. genetic drift, inbreeding, less diversity -environmental stochasticity .. changes in weather and biotic factors *minimal viable population (MVP)* - the acceptable pop size that ensures some acceptable probability of persisting for a specified time
Geometric Growth Model
-population growth is multiplicative -population becomes large -For dt, individual has a probability b of giving rise to another individual and a probability d of dying
Habitat loss and fragmentation effects
-reduced habitat area -increased fragmentation -increased distance among fragments -reduced genetic variation in isolated population figure see lecture 12 p2
overfishing
-removal of too many fish -rate of biomass removal exceeds rate at which biomass is being replaced why does it keep happening?? -basic supply and demand .. related to pop increase and chicken feed -incomplete data on stock abundance, recruitment, etc -failure to make timely management decisions -politics and economics ex) *Ludwigs rachet* -- happens when harvestable resource fluctuates from the stable pop eq --harvesting rate is good = increased harvest = more investment --harvesting bad = appeals for subsidy = maintain investments = maintain harvest (no change)
Experiments by Janzen
-removed ants from acacias -acacias quickly overgrown -more herbivorous insects without ants
effects of disease on reproduction
-reproduction (clutch sizes) are lower -population limitation and regulation affects.. density dependent pop regulation ex) lizards with malaria dont produce as much fat and their clutch size is 20% lower when infected ex) bird chicks are attacked by parasites in their nests and if parasite infestation is severe than reproductive output is reduced -birds that repeatedly use the same nest are very susceptible to these *ectoparasites* - parasites that live outside of host organism experiment: -bird nests were measured for clutch sizes with no fumigation, one fumigation, multiple fumigation's -found that there was a higher clutch size and chicks had a bigger mass *IN CLASS EXAMPLE*: ex) isopod lives on the gills of fishes.. but its a parasitic castrator. takes so much energy from the fish that the fish cant expend any energy towards gonad development
economic model for fishing
-revenue/benefit from fishing is assumed to be directly proportional to the yield -yield curve is identical to the revenue curve in this model -max sustained yield is the peak of the curve .... NOT at the same point as *max economic rent*(total revenue-total costs) -*max economic profit will occur at a lower fishing intensity than max yield* -if UNMANAGED.. then the only social eq will be reached at the point where total costs equal the total revenue .. which is beyond the point of max sustained yield ISSUE -discounting of future returns... why would i delay the harvest if i can harvest everything now before someone else does
chains of extinctions
-secondary extinctions of species that depend on species that have become extinct -large predators become extinct after their prey go extinct -require specialist relationships.. more typical in tropical areas ex) forest eagle ex) condors ex) footed ferret associated with decline in main food.. prairie dogs ... currently being reintroduced into areas where prairie dog colonies are safe ..... it is still not safe bc it is susceptible to the canine distempter
Biology of population decline
-small populations -declining populations -many populations are small or in decline currently figure see lecture 12 p1
marine reserve implementation
-sociopolitical process -stakeholder/community involvement -must consider economic impacts... balance of short/long term gains -role of science: guide design, evaluate options, monitoring and evaluation *monitoring and evaluation*- once reserves are in place, need to evaluate if they are effective at accomplishing stated goals "BACIPS" (before-after-control-impact-paired-series) -need to match empirical monitoring data with theoretical expectations
interference competition
-some individuals acquire resources at the expense of other individuals -*winners/losers*
Conservation in practice
-species management plans -captive breeding -protected areas -restoration
Resource Partitioning
-species specialize in different resources -does not occur right away -reduces resource overlap & reduces intensity of competition -produced by natural selection
conservation biology
-the biology of small populations and decline and scarcity -humans impact other species.. any natural resource impact both indirect and direct (humans dont cause all extinctions some are due to chance) 2 approaches: 1. small population paradigm 2. declining population paradigm
epidemiology
-the branch of medicine that deals with the incidence, distribution, and possible control of diseases and other factors relating to health. -models are applicable to many ecological systems in which birth, death, and infection processes are continuous in time
Ecological evidence
-the distribution of species alone vs. together competitive exclusion: one species is eliminated competitive release: removal of one species allows expansion of the other's range
character displacement
-the divergence in morphology between similar species in the region where the species both occur -this divergence is reduced or lost in regions where the species' distributions do not overlap -caused by competition reasons for occurring 1. maintain reproductive isolation 2. interspecific competition in critical niche dimensions evolutionary change must fit this criteria: 1. the pattern observed could not have occurred by chance 2. the observed phenotypic differences have a genetic basis 3. the trait differences should result from actual evolutionary changes 4. the morphological differences should reflect differences in resource use 5. the sites of sympatry and allopatry should not differ greatly in environmental factors that affect the phenotype 6. there must be independent evidence for competition between the species sympatric- beak depths differ allopatry- beak depths are the same
how to control disease outbreaks
-transfer indiv. from susceptible to removed -vaccination -allowing them to get and recover from the disease -culling finding out how many organisms we have to treat: c > 1 - y/B = 1 - 1/Ro ---so say Ro is 4. then 1 - 1/4 = 0.75 = 75% of pop need to be vaccinated/culled to control disease
Types of Predators
-typical (including cannibalism) -herbivores -parasites (and parasitoids) see figure 11.2 p191
dynamic pool model
-uses more biological realism than the logistic model -age/size specific growth, mortality, fecundity, recruitment -can be modified to include effects of density dependence ex) plaice fishery in North Sea -plaice spawn in midwinter when females are 5-7yrs and males are 4-6yrs... females have enormous reprod. potential that is balanced by high mortality -about 10 out of a million eggs survive ... much loss occurs during the pelagic when eggs float as plankton until hatching.. and teh larval plaice are carried by currents for 2 months until they settle down.. the young plaice remain here for 2-3 yrs... then move off the coast where they are caught -pop has been stable except for when world wars happened and pop increased a lot 1. determine growth rate with respect to age 2. specify recruitment of young fish into the pop 3. determine natural mortality rate of adults ---combine 3 factors to get yield curve =increased yield would result from lower fishing mortality
deterministic extinctions
-vital resources are removed and/or lethal agents are introduced (changes to birth and death rates) -overkill..hunting or fishing at a rate above populations capacity to rebound.. overharvesting until there are none left. like whales -habitat loss/fragmentation... agricultural fragments landscapes bc we only leave small amounts of land untouched -introduced species.. invstions of exotic species.. intentional or unintentional -chains of extinctions... secondary extinctions of species that depend on species that have become extinct.. large predators go extinct after their prey goes extinct
predation
-when one organism kills and eats another -"typical": cheetah eating a gazelle, trout eating mayflies, cannibalism (fishes, reptiles) -parasitoids: tarantula hawk - tarantula (kills/consumes host.. not the same as parasite) impacts 1. distribution and abundance 2. population regulation 3. community structure 4. natural selection --- do not only interact with their prey species, they also interact with other predators via competition .. may be indirect when species eat the same prey that is in short supply or via prey speceis that themselves compete for space or food
metapopulation dynamics
1. *"classic" metapopulation dynamics* -colonization and extinction rates of individual patches -ex) Huffaker's experiments with mites to determine what conditions are responsible for pred/prey coexistence 2. *source-sink dynamics* -subpopulations don't necessarily go extinct -some populations contribute more indiv. than others -*source population*- birth rates exceed death rates so that pop growth is positive -*sink populations*- death rates exceed birth rates so that pop growth is negative .. would not persist without replenishment from other populations
3 basic harvest strategies
1. *constant quota*- a fixed catch does not change with stock size. if the stock is large the catch will be a small fraction of the population .. if the stock is small the entire stock may be taken 2. *constant exploitation rate*- the catch does not rise one-to-one with stock but instead at some lower rate... ex) the catch might rise 0.5 times the stock rise. the escapement thus increases as stock grows larger. a variant of this strategy uses a threshold or lower limit point so that the fishery is closed at low stock abundance 3. constant escapement- the catch will rise one-to-one with the stock size and that the stock size or escapement will not vary. this strategy has an implicit threshold so harvest begins only when the size of the stock exceeds threshold
reserves in the ocean
1. *marine protected area (MPA)* -an area set aside for specific conservation goals that may restrict certain types of harvest and/or other human activities 2. *marine reserve* -a specific type of MPA -a permanent area where no extraction of living resources or alteration of habitats is allowed goals: -conservation of fished species -conservation of biodiversity -fisheries management -socioeconomic benefits (ecotourism)
conservation in practice
1. *species management plans* -MVPs, PCAs, assessing/correcting causes of decline 2. *captive breeding* -to enhance existing natural but endangered speceis 3. *protected areas* -setting aside land and waters for protecting species and communities 4. *restoration* -restoring habitats that have been degraded or destroyed -big question: to what state do we restore the habitat *dont let advocacy interfere with objectivity*
Outcomes of Competition
1. Competitive exclusion (one population being excluded from the community). 2. Coexistence (Both populations can exist)
Probability of extinction
1. Demographic stochasticity - chance extinction in birth and death rates 2. Genetic stochasticity - genetic drift and inbreeding 3. Environmental stochasticity - variation in population growth rates by changes in environmental condition
Disperal types
1. Diffusion. (movement of population across hospital terrain through gradually long period of time) 2. Jump. (movement of population across inhospitable terrain that takes place rapidly)
classification of interactions
1. competition -negative for both species 2. predation, herbivory, disease, parasitism -positive for one species negative for another 3. mutualism/facilitation -positive for both
take home message about competition models
1. competition can drive one species extinct 2. some competitive interactions can lead to coexistence 3. we can understand competition by only knowing the *resources involved* and the *mechanisms* by which species compete ---ex) exploitative competition: -occurs when a number of organisms (of the same or different species) utilize common resources that are in short supply...all individuals are equally affected no winners/losers
how to selection reservations
1. decide on the objective of the reserve system clearly and unambiguously 2. identify which areas of land are available for designation as reserves within the terms of the objectives decided in step 1 3. survey each patch that might become a reserve and obtain a list of species present, and if possible, an estimate of abundance of each 4. formulate a starting rule for selecting the first reserve and how subsequent patches will be chosen in sequence
6 plant-herbivore interactions
1. defensive chemicals are widespread among plant species 2. individual plants or species have an array of defenses rather than only one defense against herbivores 3. many plants have dynamic defenses against herbivores, so they can respond chemically or physically once they are attacked 4. characteristics of the environment (or resource availability) affects the ability of plants to mount defenses against herbivores 5. there is geographic variability in the interactions between plants and herbivores so that not all populations of a species have the same defenses 6. plant adaptations and herbivore feeding specialization reflect their evolutionary history
K-selection
1. large sized organisms 2. few larger reproductive units 3. much energy used to produce one reproductive unit 4. late maturity and often parental care 5. long life expectancy 6. many reproductive episodes (iteroparous) 7. type 1 / 2 survival curve .. constant mortality or high mortality late in life
pred/prey system dynamics in field work
1. multiple prey species being eaten by multiple predator species 2. refuges for prey 3. spatial (and temporal) heterogeneity in habitat suitability for both the predator and prey 4. evolutionary changes in predatory prey characteristics (coevolution)
Four causes of extinction
1. overkill 2. habitat destruction and fragmentation 3. introduced species 4. chains of extinction
how do prey persist?
1. protection from predators *refuge* -escape in space (shelter) -escape in size ex) mussels hide in shelter for 7 years until they are too big to be eaten by starfish -escape in numbers (swamping..dilution effect/predator satiation/confusing predators) 2. evolution of escape capability and warning coloration -"life-dinner" principle... selection should be stronger on prey because they lose their lives if they lose.. predators only lose a meal -warning coloration... distasteful or toxic, signal to predators to avoid consumption, mimicry: tasty species that look like distasteful ones 3. *optimal foraging theory*-- predators can feed on more than one prey but they prefer one over the other .. may switch between the two as relative abundance of different prey species change ... can be important to stabilize density fluctuations in prey pops.. or switching can help a prey pop recover -generalist pred stabilize prey numbers -specialist pred cause instability
defense mechanisms in plants
1. structural (spines, tough/waxy cuticles) 2. chemical (secondary defense compounds, metabolic byproducts) 3. can be *inducible* (produced only when a plant is damaged by herbivore) 4. evolve self regulatory mechanisms that hold their own numbers in check and prevent them from destroying their food supply 4 general predictions if a plant defense has a cost in terms of plant fitness: -plants evolve more defenses if they are exposed to much damage, and fewer defenses if the cost of defense is high -plants allocate more defenses to valuable tissues that are at risk -defense mechanisms are reduced when enemies are absent, and increased when plants are attacked -defense mechanisms are costly and cannot be maintained if plants are severely stressed by environmental factors
reserve aims
1. to conserve specific animal/plant communities that are subject to change bc of fire, grazing, or predation. these reserves must be managed by intervention to set the permissible levels of fire, grazing and predation 2. to allow the system to exist in its natural state and to change as governed by undisturbed ecological processes , so that no attempt will be made to influence the resulting changes in populations and communities
risk-aversive management strategies
1. to impose a constant percentage harvest on a population 2. to harvest all indiv above a threshold population size and no individuals below that threshold -problem with fisheries is that the threshold is set too low to sustain the resource --impose protected areas so that the stock will remain at greater than 60% of carrying capacity over a given time horizon ... fisherman can harvest at a specific rate outside of this zone but not inside
designing marine reserves
1. where? -biodiversity hot spots (rare species) -representative habitation (lifecycle habitats.. multiple habitats) -spawning aggregations -sources or sinks? protect the source 2. how big? -encompass entire home ranges -for reserve networks:consider both indiv reserve size and total area inside the reserves 3. how many? how far apart? -single vs. network -interaction with reserve size: total area in reserve -*equivalence in yield*: closing x percent of fishing grounds produces the same yield as reducing fishing effor by x percent over the entire area ... ex) fishing at 100% effort over 60% of the available habitat produces equal yield to fishing at 60% over 100% available habitat *scorched-earth assumption* (pops only exist in reserves and are fished to extinction outside reserves) -for metapopulations to persist at least one reserve must be demographically persistent (recruitment rate exceeds death rate Ro>1) -*self persistence*.. adults produce enough larvae that are retained within that single reserve so Ro>1 -*network persistence*.. adults produce larvae that may disperse to other reserves, but population persists as along as those other reserves eventually contribute enough larvae back to the original reserve in subsequent generations so long term average Ro>1 -persistence of spatial populations depends on returning home -spacing between reserves depends on larval connectivity
What are 4 main causes of deterministic extinctions?
1.) Overkill 2.) Habitat Destruction/Fragmentation 3.) Introduced Species 4.) Chains of Extinction
Diseases or parasites have been shown to affect?
1.) Reproductive output 2.) Survivorship/mortality 3.)Behavior
Why is it extremely unlikely that SWS is related to leaked radiation at Fukushima power plant in Japan?
1.) SWS predates Fukushima 2.) SWS occurs on Atlantic Coast 3.) Other organisms are unaffected
What are two major ways we dicussed by which the size of prey may influence their willingness to respond to predators (or engage in risky behaviors)?
1.) Sea stars attacking Sea Urchins, who consumes seaweed. Small sea urchins respond more strongly to those predators than the large urchins. This is because the smaller urchins are easier to eat. The larger urchins can use their size as refuge. 2.) Juvenile male dolphins enter tiger shark habitat more of ten than other age/sex classes This is because the smaller ones are willing to take a higher risk because if they enter those habitatism, the habitat quality is higher, so they can grow faster, form earlier alliances and have access to females.
What are the outcomes of competition?
1.) Species 1 goes extinct 2.) Species 2 goes extinct. 3.) Coexistence
Five main functions of mutualism?
1.) Trophic (sharing food resources) 2.) Dispersive (Spreading seeds) 3.) Defensive (production from consumers) 4.) Nutritional (nutrients shared) 5.) Energetic (energy shared)
What are the steps to conserving declining populations?
1.) figure out what is causing the decline 2.) Remove/migrate sspecific cause(s) 3.) Done on a case by case basis -Though thre is no general rule that can protect all species in all situations
A fish maturing late with large body size and producing many small offspring would be said to have a(n) A) periodic life history. B) opportunistic life history. C) equilibrium life history. D) precocial life history. E) stress-tolerant life history.
A
Caughly's research on the distribution of three different species of Australian kangaroos (Macropus giganteus, M. fuliginosus, and M. rufus) suggests the A) physical environment limits the distribution of the kangaroos. B) topography limits the distribution of the kangaroos. C) amount of rainfall limits the distribution of the kangaroos. D) temperature limits the distribution of the kangaroos. E) None of the choices are correct.
A
Darwin is often considered the father of evolutionary thought. Which of the following terms is/are not part of Darwin's analysis? A) gene frequencies B) natural selection C) adaptation D) fitness E) None of the choices are correct.
A
Grime's classification of plant life histories focuses attention on A) stress and disturbance.
A
If the age distribution diagram is bell shaped or the number of individual in each age class is evenly distributed, this indicates that the population is A) stable. B) declining. C) growing slowly. D) growing rapidly. E) not able to be determined.
A
In a population of lizards, the average and long length tails are selected against and the short tails are selected for. This is an example of A) directional selection. B) disruptive selection. C) stabilizing selection. D) natural selection. E) balanced polymorphism.
A
In experiments with the prairie grass Andropogon, root:shoot ratios proved to be A) higher in plants grown in poor soils. B) lower in plants grown in poor soils. C) equal in plants grown in poor and rich soils. D) higher in plants grown with mycorrhizae. E) equal in plants grown with and without mycorrhizae.
A
In mature white pine forests of New Hampshire A) belowground interspecific competition suppresses the growth of herbaceous plants and hemlocks.
A
In the Lotka-Volterra predation model, a prey (host) population in the absence of predators would A) grow exponentially.
A
Mycorrhizal fungi acquire _________ from their plant partners. A) sugars B) soil nutrients C) proteins and lipids D) growth hormones E) protection from consumers
A
Nutrient poor soils should favor mycorrhizal fungi that are A) less aggressive at obtaining sugars from their plant host.
A
Seeds bearing eliasomes are likely to be dispersed by A) ants. B) wind. C) water. D) birds. E) scatterhoarding mammals.
A
The "unsuccessful mutualists" in Kathleen Keeler's cost-benefit model of mutualism are those that A) give benefits to their partner, but fail to receive benefits in return.
A
The major benefit obtained by aspen sunflower, Helianthella quinquenervis, from its ant mutualists is A) reduced losses of seeds to seed predators. B) reduced loss of leaf tissue to herbivorous insects.
A
The presence of parasitic protozoa in a culture of competing Tribolium castaneum and T. confusum A) can reverse the outcome of competition. B) decreases the likelihood of coexistence. C) has no effect on the outcome of competition. D) increases the likelihood of coexistence. E) has an effect on the outcome of competition only in the presence of predatory birds.
A
The principle of allocation states A) if an organism uses energy for one function it reduces the amount of energy available for other functions.
A
Which of the following word pairs are mismatched? A) random distribution; aggressive interaction
A
What is a fear-released system? what causes it?
A Tiger shark removed due to human involvement, will remove the fear aspect from a lower trophic level. The change in cues will cause a change in species behavior.
Density Mediated Indirect Interactions
A first species cause a change in population of a second species, which causes a population change in a third species
Mutualism
A relationship between two organisms of different species that benefits both species, and harms neither. -ex: fish and shrimp
Functional Response by predators to their prey
A response of an average predator to pey abundance (i.e. predator individuals change number of prey eaten)
Adaptation
A trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection.
Realized Niche
AFFECTED BY OTHER FACTORS. Shrunken fundamental niche. -Go and find specific measures of occurrence in environment (measure temp and humidity)
Interference competition
Aggressive competition between competing species over a SHARED RESOURCE
Niche Theory
All environmental factors that are related to a species GROWTH, SURVIVAL, and REPRODUCTION
Fundamental Niche
All of the environmental factors relevant to a species survival and reproduction
Niche
All the environmental factors relevant to a species growth, survival and reproduction -resources used -tolerances to abiotic factors -"n-dimensional hypervolume"
Local adaptation of the amphipod Ampithoe.
Amphithoe hides out in chemically dfended seeweed (Dictoyta), reducing its predation risk. Amphipod population differe in performance on Dictyota, which suggests that herbivores can locally adapt to perform better on chemically defended seaweeds.
Why do models that consider competition have conversions between species?
An individual of a species may not have the same ecological effect on an environment as another species.
How might intertidal communities impacted by SWS change relative to unifected areas/times?
An intertidal communities impacted by SWS could possibly have an increase in the urchins population and therefore a loss of seaweed coverage.
Interspecific competition Theory
Analyzed with logistics growth
Dispersive mutualism
Animals transporting pollen or seeds of plants in return for food Example: plant-pollinator mutualism A variety of adaptations for this interaction: Plants: colored flowers, nectar, odors, flower structures, flowering times Pollinators: flight and structural adaptations Other examples: animal-dispersed seeds
Dispersive Mutualisms
Animals transprting pollen or seeds in exchange for fodo -variety of evolutionary adaptations
Desribe the interaction between Acacia plants and ants
Ants defent the acacia plants while feeding on the acacia's nectaries and beltian bodies. An example of defensive and nutritional mutualisms.
Complex species interactions
Ants, green scale (insect), and plants Ant-scale interaction: +, + Scale-plant interaction: +, - Ant-plant interaction: 0, + see figure lecture 10 p3
Which region might show the greatest community-level impacts of Seastar Wasting Syndrome?
Areas of intense upwelling
Tilman?
Argued that we need to understand the LIMITING RESOURCES and how COMPETITION is occurring
coevolution leading to tight coevolution and more extreme traits occurring over generations
Arms race
What must be considered when conducting ecological restoration projects?
Ask: to what state do we restore the habitat?
Compensatory Continuum Hypothesis
At high competition/low nutrient availability, plants tend to under compensate (they "grwo worse" when attacked). At low competiton/high nutrient availabiltiy, plants tend to over compensate ( they "grow better" when attacked).
any stimulus that is unpleasant
Aversive stimulus
A species feeding on the tissue of its host, while not killing it directly, is a A) predator. B) parasite. C) parasitoid. D) cannibal. E) debilitator.
B
An annual plant when initially colonizing an area will probably demonstrate A) annual growth rate. B) geometric population growth. C) exponential growth rate. D) logistic growth. E) None of the choices are correct.
B
Analysis of the Lotka-Volterra competition model implies that two competitors can coexist only when A) interspecific competition is stronger than intraspecific competition. B) intraspecific competition is stronger than interspecific competition.
B
Ants on the aspen sunflower, Helianthella quinquenervis, obtain sugars and amino acids by A) collecting nectar from the sunflower's flowers. B) collecting nectar from extrafloral nectaries. C) tending aphids that extract plant sap. D) extracting plant sap directly by piercing the sunflower stem. E) All of the choices are correct.
B
As a fraction of adult mass, the mass of offspring at independence tends to be largest in A) mammals. B) altricial birds. C) lizards. D) both mammals and lizards. E) All three groups have similar values.
B
Crabs and shrimp associated with corals protect their hosts from A) being dislodged from the substrate by currents. B) predation by sea-stars.
B
Ecologists sometimes use __________________ as simpler representations of the complex natural world. A) character displacement B) mathematical or laboratory models C) competition coefficients D) replication E) None of the choices are correct.
B
For thousands of years, humans have bred domesticated plants and animals to produce and maintain desirable traits, such as large fruits. Darwin used which term to describe this: A) mutation. B) artificial selection. C) phenotypic plasticity. D) genetic engineering. E) natural selection.
B
In a population of birds, the average beak size is selected against and the large and small sized beaks are selected for. This is an example of A) directional selection. B) disruptive selection. C) stabilizing selection. D) natural selection. E) balanced polymorphism.
B
In order to determine whether a species is common or rare, ecologists use all of the following criteria except: A) habitat tolerance. B) evolutionary existence.
B
In the Lotka-Volterra model, the rate of predation is represented by A) c. B) p. C) cp. D) dpNp E) dp
B
Periodical cicadas spend 13 or 17 years A) feeding in tree twigs before emerging as adults. B) feeding on tree roots before emerging as adults. C) as adults before laying eggs. D) in a resistant, resting egg before hatching as larvae. E) None of the choices are correct.
B
Soil fertilization should favor mycorrhizal fungi that are A) less aggressive at obtaining sugars from their plant hosts. B) more aggressive at obtaining sugars from their plant hosts. C) more efficient at extracting inorganic nutrients from soils.
B
The Lotka-Volterra predation model predicts that predators and prey, living together, will show A) oscillations in population size that increase in amplitude through time. B) oscillations in population size that remain of constant amplitude through time. C) oscillations in population size that decrease in amplitude through time. D) oscillations, but only when outside forces such as climatic variation are also present. E) steady equilibria in population sizes.
B
The interaction between honeyguide birds and the Boran people of Kenya A) is an obligate mutualism. B) is a facultative mutualism. C) is exploitative, with humans benefiting but honeyguides exploited. D) represents the only way a honeyguide can gain access to a beehive. E) depends only on humans following birds, not on active communication by the birds.
B
The standard error of the mean is equal to A) the sample variance divided by the sample size. B) the sample standard deviation divided by the square root of the sample size. C) the sample variance divided by the square root of the sample size. D) twice the square root of the sample size. E) twice the square root of the sample variance.
B
The study of the relationship between climate and the timing of ecological events is called A) ecology. B) phenology. C) oenology. D) climatology. E) life history theory
B
Type III survivorship curve indicates A) low juvenile mortality and high mortality in older adults. B) high juvenile mortality and low mortality in older adults. C) low juvenile mortality and low mortality in older adults. D) high juvenile mortality and high mortality in older adults. E) equal chance of dying at any age.
B
Which of the following is not an example of altered behavior of the pill bug, Armadillidum vulgare, when infected by the parasite, Plagiorhynchus cylindraceus? A) spends less time in sheltered areas B) positive phototaxis
B
Which of the following observations can be explained by the energetic limitation of an organism's total reproductive effort? A) Darter diversity is very high in the Ozark Highlands. B) Darters that lay many eggs lay smaller eggs, on average. C) Seed size in plants varies over at least 10 orders of magnitude. D) Seed size in plants depends in part on the plant's seed dispersal mechanism. E) More than one of the choices.
B
______________ is/are defined as a group of potentially breeding organisms within a species in a given space and time. A) Density B) Populations
B
Coexistence: Lab
Beetle larval feeding behavior: Larve feeds on wheat grain. One feed on inside and one on outside. Feeding on DIFFERENT areas.
Predator responses to increases in prey population
Behavioral Responses: -Functional response (# prey consumed per predator/unit time) -Aggregative response (concentration of predators to areas of higher prey concentration Population response -Numerical response (increase in predator birth rates) -Developmental response (increase in predator growth rates) see lecture 9
Intraspecific
Between one species
Interspecific
Between other species, two species
Predator induces response in prey by:
Biological changes. -Crab cues: Thicker shell on snails but smaller because don't eat as much when around.
Species Interactions
Biotic Interactions between species which impact population dynamics and regulation
The rate at which a population of a species will increase when there are no limits on its rate of growth.
Biotic potential
What habitat are blue crabs most abundant (accordigng to Hovel and Lipcius 2001)?
Blue Crabs are most abundant in continuous sea grass
Why might have profound impacts on communities when they infect keystone species?
By removing the keystone species, you allow for a possible change in lower trophic levels behavior. There is also the possibility that in the absence of the keystone species, the bio diversity may decrease as species out compete for resources.
'Rarity II' can be described as A) restricted range, narrow habitat tolerances, and small local populations. B) restricted range, broad habitat tolerances, and large local populations. C) extensive range, narrow habitat tolerances, and large local populations. D) restricted range, broad habitat tolerances, and small local populations. E) extensive range, broad habitat tolerances, and small local populations.
C
A polymorphic locus is one that A) codes for more than one protein. B) codes for both protein and lipid. C) occurs in a population as more than one allele. D) occurs on more than one chromosome. E) can cause more than one phenotype in an individual, depending on the environment.
C
Among fish species, an "opportunistic" life history is characterized by A) high juvenile survival, large numbers of offspring, and early maturity. B) high juvenile survival, large numbers of offspring, and late maturity. C) low juvenile survival, low number of offspring, and early maturity. D) traits that maximize colonizing ability for environments that do not vary much in time or space. E) traits that maximize colonizing ability for environments that are very stressful.
C
Bethel and Holmes demonstrated A) positive phototaxis in Acanthocephalans infected by amphipods. B) negative phototaxis in Acanthocephalans infected by amphipods. C) positive phototaxis in amphipods infected by Acanthocephalans. D) negative phototaxis in amphipods infected by Acanthocephalans. E) increased herbivory by amphipods infected by Acanthocephalans.
C
Density is defined as A) the number of individuals within a population. B) abundance. C) the number of individuals per unit area. D) the distribution of individuals within a given area. E) None of the choices are correct.
C
Field experiments differ from laboratory experiments in that C) laboratory experiments allow variables not of direct interest to be controlled, while in field experiments these typically vary. D) field experiments can teach us about ecological systems, but laboratory experiments cannot. E) field experiments are often used by ecologists, but laboratory experiments never are.
C
In the Lotka-Volterra predation model, a predator population in the absence of prey (hosts) would C) decline as predators die. D) decline at first, but then increase as predators switch to other modes of feeding. E) decline at first, but then reach a small equilibrium population size.
C
Joseph Connell discovered that Balanus barnacles were excluded from the upper intertidal zone by ____________, while Chthalamus barnacles were excluded from the middle intertidal zone by ___________. A) competition from mussels, prolonged immersion in water B) competition from mussels, competition with Balanus C) prolonged exposure to air, competition with Balanus D) prolonged exposure to air, competition with algae E) predation by wading birds, predation by starfish
C
Over time, average phenotypes become less common and the population becomes phenotypically more diverse as a result of _____________ selection. A) bimodal B) directional C) disruptive D) stabilizing E) disjointed
C
The "K" in "K-selection" comes from the A) ecologist who coined it, Astrid Kodric-Brown. B) shape of the age-vs.-mortality-rate plot for K-selected species. C) "K" in the logistic growth equation. D) Greek letter "kappa," symbolizing fecundity. E) None of the choices are correct.
C
Which aspects of the biology of zooxanthellae are controlled by their coral hosts? C) the release of photosynthetic products from their cells D) the rate at which they absorb sugars from their hosts E) their mortality rate
C
Which of the following is NOT a characteristic favored by K-selection? A) low intrinsic rate of increase B) late reproduction C) many, small offspring D) repeated bouts of reproduction E) strong competitive ability
C
Which of the following is NOT true of riparian plant communities? C) low species diversity, compared to surrounding terrestrial communities D) high population densities, compared to surrounding terrestrial communities E) seriously impacted by human activities
C
Which of the following is not a benefit provided by mutualistic crab and shrimp to the Pocillopora coral? A) protection from predators B) promotion of the health and integrity of coral tissue C) source of lipids D) both protection from predators and source of lipids E) both promotion of the health and integrity of coral tissue and source of lipids
C
Which of the following statements is/are true? A) Population growth in humans can be represented by an S curve. B) The human population has reached carry capacity. C) Population growth in humans is exponential.
C
Which statement about snowshoe hare and lynx populations in boreal Canada is false? C) Snowshoe hares rarely deplete their food supply enough to affect their population biology. D) Trapping records kept by non-scientists can provide useful records of hare population sizes. E) Field experiments imply that hare cycles depend both on the hares' food and their predators.
C
Which statement about the impact of dams on cottonwood forests is false? A) Damming reduces growth of established cottonwoods downstream. B) Damming increases mortality of established cottonwoods downstream. C) By reducing flooding downstream, damming improves cottonwood seed germination. D) The timing of water release from a dam can greatly affect cottonwood seed germination. E) Careful management of flow through dams can greatly reduce harmful impacts on cottonwoods downstream.
C
Whittaker's research on North American tree distribution examined ____________ gradients and concluded that the tree distribution was __________________. A) temperature; random B) temperature; clumped C) moisture; clumped D) moisture; random E) soil; random
C
__________ consume live plant material but do not usually kill plants. A) Predators B) Pathogens C) Herbivores D) Parasites E) Parasitoids
C
when changes to traits in one species lead to changes in another causing feedback
Coevolution
Predation and natural selection
Coevolution - responses by predator and prey Warning coloration - advantage: "don't eat me or you'll be sorry!" Minicry - advantage to look like unpalatable species Group living - advantage: dilution effect, detection of predators, confusion effect; Disadvantage? competition, predator
Resources partitioning
Coexistence: -Ecologically similar species do co-occur: how? -Resource partitioning: species specialize on different resources -reducing resource overlap, which reduces intensity of competition Produced by natural selection "ghost of competition past" or simple coexistence without competition (requirements of each species differs)?
Periodical Cicadas
Combined functional and aggregative response Increase % consumption of prey at lower prey densities see lecture 9
Interspececific
Competition between species
Exploitative Competition
Competition of shared, limited resource (aka resource competition)
Intraspececific
Competition within species
How does coexistence of species occur?
Competitive exclusion Birch's grain beetle experiments -two species, grown in wheat together
What is a major conclusion from simple laboratory experiments on competition?
Competitive exclusion is common in the lab, but rare in nature This can be from partitioning of niches.
Trophic mutualism
Complementary modes of nutrition Example: lichens Mutualistic interaction -alga (photosynthetic) -Fungus (heterotrophic) Fungus provides nutrients; alga shares photosynthate
Sustainability and impacts
Concern for recent fisheries trends and the difficulties of current management 1) overexploitation (targeted species and bycatch) 2) bycatch 3) habitat destruction 4) indirect (cascading effects on rest of ecosystem 5) management that's ineffective at addressing all of the above concerns
Exploitative/Resource Competition
Consumption of a shared limited resource
What is an exmple of a host that can experience parasitic castration by barnacles?
Crabs
System of information transfer that affects and individual's phenotype by means of either teaching or social learning
Cultural Transmission
An interaction between individuals of different species that benefit both partners is called A) commensalism. B) predation. C) exploitation. D) mutualism. E) ammensalism.
D
Because natural selection has shaped fish life histories, A) fish species with high adult mortality tend to mature at a younger age. B) fish species with high adult mortality tend to mature at an older age. C) fish species with high adult mortality tend to invest relatively large amounts of energy in reproduction. D) Both fish species with high adult mortality tend to mature at a younger age and fish species with high adult mortality tend to invest relatively large amounts of energy in reproduction are true. E) Both fish species with high adult mortality tend to mature at an older age and fish species with high adult mortality tend to invest relatively large amounts of energy in reproduction are true.
D
Competition between members of a single species is called A) cohort specific competition. B) species specific competition. C) interspecific competition. D) intraspecific competition. E) interference competition.
D
Density dependent factors include all of the following except: D) temperature. E) None of the choices are correct.
D
During droughts in the Galápagos Islands, the ground finches most likely to survive are those with A) smaller bodies. B) smaller bills. C) earlier maturation. D) larger bills. E) larger territories.
D
Ephemerellid mayflies under attack by stoneflies will typically A) swim away to escape possible predation. B) rely on their cryptic coloration to escape detection. C) rely on their spiny appendages to deter attack. D) adopt a posture which increases their apparent size, so that the predator will avoid them. E) burrow into the stream bottom.
D
Gause's "competitive exclusion principle" states that D) no two species with identical niches can coexist indefinitely. E) None of the choices are correct.
D
Gause's laboratory experiments with Paramecium species provided evidence for: D) competitive exclusion principle. E) All of the choices are correct.
D
If the age distribution diagram is bottom heavy or pyramidal in shape, this indicates that the population is A) stable. B) declining. C) growing slowly. D) growing rapidly. E) cannot be determined
D
In Grime's classification, stress-tolerant plants D) conserve nutrients and water. E) All of the choices are correct
D
In Kathleen Keeler's cost-benefit model of mutualism, the condition for persistence of mutualists is pwmw + qwmu > wnm. The parameters p and q represent the A) cost and benefit of the mutualism. B) fitness of successful and unsuccessful mutualists. C) frequency of "mutualist" and "nonmutualist" alleles in the population. D) proportion of successful and unsuccessful mutualists in the population. E) amount of herbivore protection provided by ant and non-ant defenses.
D
In Thomas Park's experiments with Tribolium beetles, which of the following was true? D) T. confusum and T. castaneum could coexist under some environmental conditions, but not all. E) T. confusum and T. castaneum proved to be unsuitable species for laboratory experimentation.
D
In plants, "self-thinning" refers to reduction in D) population density in response to competition, as population biomass increases. E) population density due to grazing by herbivores.
D
Mycorrhizal fungi (directly) help their plant partners acquire D) soil nutrients. E) pollination.
D
Mycorrhizal fungi (directly) help their plant partners acquire A) sugars. B) sunlight. C) seed dispersal. D) soil nutrients.
D
Plagiorhynchus worms and Puccinia rusts are parasites that share the ability to change their host's behavior in way that A) increase the length of time they can survive in their hosts. B) decrease their host's mortality rates. C) increase their hosts reproduction, thereby increasing production of parasite-infected offspring. D) increase the likelihood of their (the parasites') transmission to a new host. E) decrease the hosts' vulnerability to other parasites.
D
Raine, Willmer, and Stone demonstrated that protection and pollination mutualism do not come into conflict on the swollen thorn acacia, Acacia hindsii, because A) there is spatial separation of inflorescences and resources used by guarding ants. B) A. hindsii inflorescences lack nectar. C) A. hindsii inflorescences contain a chemical ant repellent. D) All of the choices are correct.
D
The __________ defines the physical conditions under which a species might live, in the absence of interaction with other species. D) fundamental niche E) primary niche
D
The enlarged thorns of swollen thorn acacias provide ants with D) living space. E) a habitat for their prey species.
D
The major benefit obtained by zooxanthellae algal cells from their coral host is D) nitrogen from coral wastes. E) temperature regulation.
D
Which of the following statements about damselfish on Jamaican reefs is false? A) Damselfish engage in both intraspecific and interspecific competition. B) Damselfish compete for territories they use for feeding. C) Damselfish attack intruders threatening their young. D) Damselfish without territories die. E) Competition in damselfish is "interference" competition.
D
Which statement is not true of lynx and coyote predation of the snowshoe hare? A) Lynx and coyote both show a strong numerical response to increases in the snowshoe hare population. B) Lynx show higher predation rates when snowshoe hare numbers are declining. C) Coyotes show higher predation rates when snowshoe hare numbers are increasing. D) Coyotes show a clear type 2 functional response to increases in the snowshoe hare population. E) At high hare densities, coyote and lynx predation rates exceed their daily energy needs.
D
What local adaptations do Libinia decorator craps display? (Stachowicz and Hay 2000)
Decorator crbs decorate their nest with a seaweed called Dictyota. Dictyota is a chemically defended seaweed and helps the crab fight off predators.
Density dependence
Density dependence must exist for regulation Density dependence: changes in birth and death rates with population density As population density increases, population growth rate decreases (b<d), and vice versa
Density dependence vs. density independence
Density dependence: birth & death rates change with density; biotic factors (e.g., competition, predation) Density independence: birth & death rates are independent of density; abiotic factors (e.g. temperature, rainfall)
What determines stock biomass?
Density-dependent per capita rates of reproduction and mortality see lecture 11 p 4
Which of the following has the best evidence for playing a role in Seastar Wasting Syndrome?
Densovirus
Beetles: Rhizopertha & Calandra
Dependent on temperature. One species wins at 32.3 and one wins at 29. Important because when temperature changes, consequences are that, in increase, one species will be eaten up.
Comes about from some change with no chance of escape.
Deterministic extinction
Interference Competition
Direct aggressive actions used to defend resources
Disease and parasitism
Disease: +, - interaction (microparasites)--benefit to disease organisms (bacteria, viruses) and detriment to host Parasitism: +, - interaction (macroparasites) Disease and parasitism can have large impacts --lethal and sublethal --reduces fitness --interaction with other processes (e.g., predation) see figure lecture 10 p4-5
"Riparian" refers to plant communities occurring A) in the tropics. B) at high altitudes. C) along the edges of deserts. D) in permanently flooded areas. E) in transitions between riverbanks and upland areas.
E
'Rarity I' can be described as: A) restricted range, narrow habitat tolerances, small local populations B) restricted range, broad habitat tolerances, large local populations C) extensive range, narrow habitat tolerances, large local populations D) restricted range, broad habitat tolerances, small local populations E) extensive range, broad habitat tolerances, small local populations
E
A "forb" is a(n) A) fish species living in the open ocean. B) bird species having offspring independent at a young age. C) plant species with woody tissue. D) grass or sedge. E) herbaceous, but non-graminoid, plant species.
E
A "negatively phototaxic" amphipod will swim A) away from parasitic worms. B) towards parasitic worms. C) away from competing amphipods. D) towards light. E) away from light.
E
A calculated range of values that we estimate contains the true mean of a population with a known degree of certainty is called a A) standard error. B) standard deviation. C) median. D) Students t-value. E) confidence interval.
E
A group of subpopulations living in spatially isolated patches connected by exchange of individuals among patches is called a(n) E) metapopulation.
E
Adaptation to the environment by a population does not include A) variation in characteristics among individuals in a population. B) evolution. C) improved ability to live in the environment. D) anatomy, physiology, and behavior. E) None of the choices are correct.
E
Ant-acacia trees provide several services to their mutualistic ant partners. These include E) Both enlarged thorns to host ant colonies and nectar from foliar nectarie
E
Evolution results from A) mutations. B) natural selection. C) genetic drift. D) gene flow. E) All of the choices are correct.
E
Gause's experiments with Paramecium and Didinium showed E) coexistence of predator and prey with oscillating population sizes, but only in the presence of refuges and predator reservoirs.
E
In the Lotka-Volterra predation model, the predator death rate is represented by A) c. B) p. C) cp. D) dpNp. E) dp.
E
Intraspecific competition among planthoppers A) results in reduced survivorship. B) results in increased development time. C) occurs via resources rather than interference. D) occurs because plants exploited by planthoppers have less protein and less moisture. E) All of the choices are correct.
E
Research on North American bird populations have indicated that populations are _____________, distributed on a __________________ scale. E) clumped; large
E
Self-thinning in a stand of trees A) increases biomass per individual. B) decreases stand density. C) results in death of less competitive individuals. D) is a result of intraspecific competition. E) All of the choices are correct.
E
The age distribution of a population can reveal E) growth potential, survivorship, and reproduction.
E
The exponential population growth equation can be used for A) populations with overlapping generations. B) populations experiencing continuous growth. C) populations with nonpulsed reproduction. D) both populations with overlapping generations and populations experiencing continuous growth. E) both populations with overlapping generations, populations experiencing continuous growth, and populations with nonpulsed reproduction.
E
The factors that determine carrying capacity include all of the following except: A) space. B) disease. C) food. D) competition. E) None of the choices are correct.
E
The number of eggs laid by a female is called her A) fertility. B) gonadosomatic index. C) growth form. D) rotundity. E) fecundity.
E
Two species occurring together in the same place are said to be E) sympatric.
E
Type II survivorship curve indicates D) high juvenile mortality and high mortality in older adults. E) equal chance of dying at any age.
E
Which of the following are characteristics of a population? A) consists of a single species B) has an age distribution C) has a birth rate has an emigration rate All of the choices are correct.
E
Which of the following does NOT contribute to determining the niche of the salt-marsh grass Spartina anglica? D) temperature E) rainfall frequency
E
Which of the following environments for germinating seed is most likely to favor a plant species that makes many small seeds, compared to one that makes fewer larger seeds? D) deep burial in soil E) disturbance
E
Which of the following factors can stabilize predator-prey relationships by providing a prey refuge? A) an area of prey habitat where predators cannot enter B) an area of prey habitat that is isolated and difficult for predators to find C) the occurrence of prey in numbers too large for predators to attack effectively D) the ability of prey to grow to a size invulnerable to predation E) All of the choices are correct.
E
Which of the following is a correct graphical representation of the Lotka-Volterra predator-prey model? E) both predator and prey numbers are plotted against time producing reciprocal oscillations in predator prey populations and predator numbers are plotted against prey numbers producing an elliptical oscillation in predator prey numbers
E
Which of the following is a result of infection of Arabis by the plant parasite Puccinia monoica? A) formation of an elongated rosette topped by a cluster of bright yellow leaves B) formation of a pseudoflower that resembles the flower of a buttercup C) insect transfer of spermatia from one fungus to another D) elimination of seed formation by the host plant E) All of the choices are correct.
E
Which of the following organisms are dependent on mutualisms for their persistence? A) reef-building corals B) bioluminescent fishes C) bumblebees and hummingbirds D) horses, elephants, and camels E) All of the choices are correct.
E
Which statement about organisms' "niches" is false? E) In the laboratory, two species with identical niches are especially easy to maintain in a mixed culture.
E
__________ show more variation in life history traits than any other group. A) All of the choices show equal amounts of variation in life history traits. B) Mammals C) Birds D) Reptiles E) Fish
E
What must Ecology be in regards to Conservation Ecology?
Ecology must always be Objective
Bird Mites are example of what broad class of parasites?
Ectoparasites
K (carrying capacity)
Efficient resource use, predictable environments
Predator-Prey systems in the laboratory
Example: Gause's experiments with Didinium Predators can be too different see figure 11.7 p195 Oscillations by immigration into both populations Oscillations due to factors outside the predator-prey system
Contrasting geometric vs. logistic growth
Example: Reindeer introduction on islands 1. Reindeer released 2. No predators islands similar in habitat and vegetation -Geometric growth followed by "crash" due to winter food shortage
Competition in fishes
Example: competitive release (Hixon 1980: two species of surfperch on reefs) see lecture 8 page 5
density dependent natural selection (r-selection VS K-selection)
FOR UNSTABLE ENVIRONMENTS 1. *r-selection* (r = rate of increase) -in unstable habitats and remain on the rising portion of the curve for most of the year -suffer from interspecific competition and they do NOT evolve mechanisms for strong competitive ability ex) when a population initially colonizes an empty habitat ... then becomes K-selection after a given amount of time 2. *K-selection* (K = saturation density) -in stable environments organisms exists near K -BOTH intra and inter- specific competitive pressures .... push organisms to use their resources more efficiently -if K-selection is the complete description then we can predict the outcome of competition in labs...... but we CANNOT do this because of the third Lotka-Volterra parameter (alpha beta coefficients) ...... species can still evolve competitive ability in the presence of alpha -ex) after an amount of time the population that colonized an empty habitat will become K-selection 3. *a-selection* (variable from Lotka Volterra) =interference ----and mechanism that prevents a competitor from gaining access to limiting resources will increase alpha or beta and thereby improve competitive ability........ PROBLEM: affects members of the same species and members of competing species -operates when organisms are at low density ... aggressive behaviors to utilize resources GRADIENT r ---> K ---> alpha
Resource Availability Hypothesis
Faster-growing plants have lower investment in defense; slower-growing plants lose a greater proportion of their tissue to herbivores so invest more in defense --faster-growing vs. slower-growing plants see figure lecture 10
time or energy dedicated to one activity cannot be used for other activities
Foraging/predation trade-off
Why is habitat Fragmentation problematic?
Fragmentation is problematic, because it reduces habitat area, reduces genetic variation in an isolated population, also increases the "Edge" effects.
Fundamental vs. Realized Niche
Fundamental: all the environmental factors relevant to a species survival and reproduction Realized: the actual set of factors observed -competition (or other interactions) limits a species from "filling" the fundamental niche
predation lab experiments (Gause bacteria)
Gause experimented with Didinium (predator) and Paramecium (prey) --could he replicate oscillations in the lab? 1. *simple homogenous environment*-reared the two together in an oat medium -prey increased exponentially and then it reached a peak... then the predator grew .... system went to extinction bc predator was too efficient 2. *prey refuge*- added a sediment as refuge for prey -many prey and no predators in the sediment -predators ate all the prey in the clear medium... then predators died of starvation -stable point was reached as expected by math model 3. *immigration of both preds and prey* - every 3rd day he added one prey and one predator -produced stable oscillations due to external forces CONCLUSION: -pred/prey numbers were NOT a property of pred/prey interaction itself but apparently a result of *interference* from outside system
This mechanism typically results in an increase in the genetic diversity of a sub-population as individuals migrate between other sub-populations.
Gene Flow
This mechanism usually leads to a decrease in genetic diversity in small populations.
Genetic Drift
Stress-Tolerant (high stress, no disturbance)
Grow slowly, conserves resources
Competitive (low disturbance low stress)
Grow well, but eventually compete with others for resources
Habitat fragmentation and destruction
Habitat loss Habitats are adversely affected: -Destruction: urban development, food production, harvest natural resources -Degradation: pollution -Disturbance: huamn recreation, ecotourism, ecological research -Fragmentation: coincident with loss of habitat
When an animal learns to become less sensitive to a stimulus over time
Habituation
This can be considered a null-hypothesis for evolution.
Hardy Weinberg
What is the best strategy for harvesting commercially important species?
Harvesting populations How is the greatest yield achieved without harming the resource? -optimum yield -stock (part of population that is harvested) -sustainability=balance between mortality vs. reproduction and growth
Why did Tilman criticize Lotka-Volterra Equations for competition?
He argued that we need to understand limiting resource and how competition is occurring
What did Gause conclude from his experiments?
He concluded that the predator-prey system was inherently self-annihilating without some outside interference, like immigration.
Allocation
How organisms spend limited resources towards survival, growth, and reproduction.
Overkill
Hunting or fishing at rate above population's capacity to rebound