BISC 208: Mini-Exam 2

MB: Succession in an ecological context refers to _______.

- the sequence of changes in species composition over time within the community after a disturbance • succession is the description of how a community changes through time

RG: Name the five main levels of study in ecology and explain why they are said to have a hierarchical relationship. Provide an example biological scenario and apply it to the levels

- (1) organisms → study the way an eagle hunts for pray - (2) populations → study how bees and wolves work together to provide for the colony or pack - (3) communities → wheat relies on the sun's rays and nutrients in the soil - (4) ecosystems → study water, nutrients, or other chemicals that cycle through the ecosystem - (5) biosphere → encompasses all ecosystems - hierarchical system because it starts small then gets bigger/ more complicated, but ecologists draw on multiple levels in research

Biomagnification

- *biomagnification*: certain molecules increase in concentrations at higher levels in the food chain - heavy metals like mercury and some persistent organic pollutants (POPs) undergo biomagnification - when consumers eat something from the lower trophic level, they ingest all of the pollutants the organism was carrying but concentrate them into smaller biomass because they are not metabolized or excreted

RG: Why do toxic substances become more concentrated at higher trophic levels?

- *biomagnification*: in animal tissues, an increase in the concentration of heavy metals (such as mercury) or persistent organic pollutants (such as DDT) as they are passed up the food chain

Population Distribution

- *clumped*: individuals in patches • resource based • mating behavior • group protection - *uniform*: evenly spaced • interactions between individuals - *random*: unpredictable • absences of strong interactions within the population

MB: Researchers hypothesize that the severe winter of 2010 caused the decline in the number of pythons encountered that year. Is cold weather typically a density-dependent factor or a density-independent factor? Explain the difference.

- *cold weather* is typically a *density-independent* factor because it affects the pythons the same way no matter whether there are few or many pythons. a *density-dependent* factor, such as *competition for food*, increases with increasing population density

RG: Describe the different categories of species interactions. Describe and example of each

- *commensalism (+/0)*: occurs when one species benefits, but the other species is unaffected • ex: sharks and the fish remoras → remoras attach themselves to the sharks and feed on left over food - *competition (-/-)*: occurs when individuals use the same resources resulting in lower fitness for both • ex: birds at a bird feeder → seed-eating birds compete with each other for the limited food - *consumption (+/-)*: occurs when one organism eats or absorbs nutrients from another. this interaction increases the consumer's fitness, but decreases the victim's fitness • ex: food chains - *mutualism (+/+)*: occurs when two species interact in a way that confers fitness benefits to both • ex: acacia trees and ants → the trees protect themselves agains plant-eating animals, but the ants that live on the trees receive protection - *parasitism (+/-)*: occurs when one organism benefits at the expense of the other • ex: tick and dogs → the tick benefits by sucking the blood from the dog making the dog sick

Competition

- *competition* is a (-/-) interaction that lowers the fitness of both individuals involved • the act of competing uses resources, so those resources are not available for foraging, mating or other activities to increase fitness - *intraspecific competition*: between members of the same species • because intraspecific competition for resources intensifies as a population's density increases, it is a major cause of density-dependent growth - *interspecific competition*: when members of different species use the same limiting resources

RG: What evolutionary impacts can inbreeding have?

- *inbreeding*: mating between closely related individuals. increases homozygosity of a population and often leads to a decline in the average fitness via selection

RG: How can understanding population demography and population dynamics be applied to protecting endangered species?

- small, isolated populations are unlikely to survive long term - preservation for later species

RG: Describe the 4 primary ways organisms exchange heat with their environment

- *conduction*: (1) direct transfer of heat between two objects that are in physical contact; (2) transmission of an electrical impulse along the axon of a nerve cell - *convection*: transfer of heat by movement of large volumes of a gas or liquid - *radiation*: transfer of heat between two bodies that are not in direct physical contact. more generally, the emission of electromagnetic energy of any wavelength - *evaporation*: the energy-absorbing phase change from a liquid state to a gaseous state. many organisms evaporate water as a means of heat loss

Heat Exchange and Thermoregulation

- *conduction*: heat is transferred from one surface to another, such as an animal on a warm rock - *convection*: currents of air remove heat from the surface of dry skin - *radiation*: sun's rays or radiating from the skin - *evaporation*: heat is removed via sweat evaporating

Demography

- *demography*: is the study of factors such as emigration that determine the size and structure of populations through time - to make predictions about the future of a population, biologists need to know ... • *age structure* — number of living individuals of each age • number of individuals of different ages likely to survive to the following year • number of offspring produced by females of each age • how many individuals of different ages immigrate and emigrate each *generation*: the average time between a mother's first offspring and that of her daughter

What factors limit population size?

- *density-independent factors*: variation in weather patterns, are usually abiotic; they change birth rates and death rates irrespective of population size - *density-dependent factors*: change in intensity as a function of population size and are usually biotic • density-dependent factors are responsible for the declining growth rates in logistic population growth • density-dependent factors like disease, predation, and competition decrease survivorship, fecundity or both

RG: How do disturbances play an important role in community composition/structure?

- *disturbance*: in ecology, any strong, short-lived disruption to a community that changes the distribution of living and/or nonliving resources - 3 factors • (1) type of disturbance • (2) frequency • (3) severity

RG: Define endotherm and ectotherm. How does each maintain body temperature?

- *ectotherm*: an animal that gains most of its body heat from external sources as opposed to metabolic processes - *endotherm*: an animal that gains most of its body heat from internal metabolic processes

Strategies for Thermoregulation Homeostasis

- *endotherm*: produces enough heat to warms its own tissues - *ectotherm*: relies on heat from the environment - *homeotherms*: keep body temperature constant - *poikilotherms*: allow body temperature to change depending on the environment - many organisms on a range of these extremes

Factors the Influence Evolution

- *evolution*: a change in allele or genotype frequency in a population over time • mutation: a source of new alleles • gene flow: movement/ exchange of genes from another population (i.e. migration) • natural selection: usually (but not always) acts to reduce genetic variability • genetic drift: random fluctuations in allele frequency - non-random mating

RG: How do species interactions determine recovery from disturbance?

- *facilitation*: the phenomenon in which early-arriving species make conditions more favorable for later-arriving species - *tolerance*: the phenomenon in which early-arriving species do not affect the probability that subsequent species will become established - *inhibition*: the phenomenon where early-arriving species make conditions less favorable for the establishment of certain later-arriving species

Fecundity

- *fecundity*: the number of female offspring produced by each female in the population - *age-specific fecundity*: the average number of female offspring produced by females in each age class - the *net reproductive rate* indicates whether the population is increasing or decreasing • depends on immigration and emigration being insignificant • when the net reproductive rate is >1, the population is increasing • when it is <1, the population is decreasing

Fitness and Species Interaction

- *fitness*: the ability to survive and produce viable, fertile offspring - when species interact ... • positive (+) → a species benefits • negative (-) → if a species incurs a fitness cost • neutral (0) → no effect on fitness - three key themes • 1) species interactions may affect the distribution and abundance of a particular species • 2) species act as agents of natural selection when they interact. this is coevolution → a pattern of evolution where two species influence each others' adaptations • 3) the outcome of interactions among species is dynamic and conditional

Food Chains and Webs

- *food chain*: one possible pathway of energy flow among trophic levels in an ecosystem - *food web*: a compact way of summarizing energy flows and complex trophic interactions that occur in ecosystems

RG: Define gene flow

- *gene flow*: the movement of alleles between populations; occurs when individuals leave one population, join another, and breed

RG: What is genetic drift?

- *genetic drift*: any change in allele frequencies due to chance. causes allele frequencies to drift up and down randomly over time, and eventually can lead to the fixation or loss of alleles

RG: Define Global Climate Change and Global Warming. What is the significance of both of these things?

- *global warming*: a sustained increase in Earth's average surface temperatures - *global climate change*: the global sum of all the local changes in temperature and precipitation patterns that accompany global warming

RG: Define homeostasis

- *homeostasis*: the array of relatively stable chemical and physical conditions in an organism's cells, tissues and organs. may be achieved by passively matching the conditions of a stable external environment (conformational) or by active physiological processes (regulatory) triggered by variations in the external or internal environment

RG: Define homeotherms and poikilotherms

- *homeotherms*: an animal that has a constant or relatively constant body temperature - *poikilotherms*: an animal whose body temperature varies with the environmental temperature

What affects population size?

- ∆N = N2 - N1 = (B - D) + (I - E) • N at time 1 (N1) and N at time 2 (N2) • births (B) and deaths (D) • immigration (I) and emigration (E)

RG: Define life history. How do fecundity and survivorship relate to this?

- *life history*: the sequence of events in an individual's life from birth to reproduction to death, including how an individual allocates resources to growth, reproduction, and activities or structures that are related to survival

RG: How can a life table be used to analyze a population?

- *life table*: summarizes the probability that an individual in a certain population will survive and reproduce in any given year over the course of its lifetime

RG: What are metapopulations? Why are they important?

- *metapopulations*: a population made up of many small, physically isolated populations connected by dispersal

RG: Explain negative feedback and give an example

- *negative feedback*: a self-limiting, corrective response in which a deviation in some variable triggers responses aimed at returning the variable to a target value - ex: thermoregulation → if body temperature changes, mechanisms are induced to restore back to normal levels

RG: What is Net Primary Productivity? What does that value?

- *net primary productivity (NPP)*: in an ecosystem, the total amount of biomass generated by the fixation of carbon through photosynthesis per year minus the amount oxidized during cellular respiration - NPP represents the total amount of chemical energy that is stored in organic matter

RG: What is niche differentiation, and how does it occur?

- *niche differentiation*: the evolutionary change in resource use by competing species that occurs as the result of character displacement

RG: What is nonrandom mating?

- *non-random mating*: mate selection is influenced by phenotypic differences based on underlying genotypic differences

Levels of Study (Ecology)

- *organismal ecology*: individuals interacting with each other and their environment? • explore the morphological, physiological, and behavioral adaptations that allow organisms to live in a particular area • ex: salmon migrate from saltwater to freshwater environments to breed - *population ecology*: how and why does population size change over space and time? • *population*: a group of individuals of the same species that live in the same area at the same time • ex: each salmon (female) produces thousands of eggs. on average, only a few offspring will survive to return to the same steam to breed - *community ecology*: how do species interact, and what are the consequences? • *biological community*: a community consists of the species that interact with one another in a particular area • asks questions about predation, parasitism, competition, and how species respond to physical disturbances • ex: salmon are prey as well as predators - *ecosystem ecology*: how does energy flow and how do nutrients cycle through the local environment? • the whole area including abiotic and biotic factors • ex: salmon die and then decompose, releasing nutrients that are used by other organisms - *global ecology*: how is the biosphere affected by global changes in nutrient cycling and climate? • ex: worldwide populations of salmon are affected by climate change - *conservation biology*: the effort to study, preserve, and restore threatened populations, communities, and ecosystems

RG: What is a population?

- *population*: a group of individuals of the same species living in the same geographic area at the same time

Important Aspects of Populations

- *population*: individuals of a single species that occupy and reproduce in the same area - aspects • size • geographic distribution • changes in the size of populations º population growth or decline º factors causing changes in population size

RG: What are the different trophic level categories? How do they relate to one another?

- *primary producer*: any organism that creates its own food by photosynthesis - *consumers*: any organism that cannot synthesize reduced organic compounds from inorganic sources and must obtain them from other organisms • primary, secondary, tertiary - *decomposers*: any organism whose diet consists mainly of dead organic matter (detrius)

RG: Describe the 5 assumptions that Hardy-Weinberg makes

- *random mating* — the model assumes that gametes from the gene pool combine at random. individuals are not allowed to choose a mate - *no natural selection* — the model assumes that all members of the parental generation survive and contribute equal numbers of gametes to the gene pool, no matter what their genotype - *no genetic drift* — the model assumes that alleles are picked in their exact frequencies p and q, and not at different frequencies caused by chance → that is, the model behaves as though the population is infinitely large - *no gene flow* — the model assumes that no new alleles are added by immigration or lost through emigration. as a result, all of the alleles in the offspring population come from the original population's gene pool - *no mutations* — the model assumes that no new alleles, such as A2, are introduced into the gene pool

Key Features of Populations

- *range*: geographic distribution of different species - abiotic and biotic factors both determine range - ranges are dynamic and in constant flux - *population density*: number of individuals per unit area — often varies throughout the range

RG: How is homeostasis achieved? What happens if this cannot be achieved?

- *regulation*: to actively maintain homeostasis of internal physiological conditions

RG: Define the following terms in the scope of how they relate to homeostasis - Set point - Sensor - Integrator - Effector

- *set point*: a normal or target range of values for a regulated internal variable, such as body temperature or blood pH - *sensor*: any cell, organ, or structure which an organism can sense some aspect of the external or internal environment. usually functions, along with an integrator and an effector, as part of a homeostatic system - *integrator*: a component of an animal's nervous system that functions as part of a homeostatic system by evaluating sensory information and triggering appropriate responses - *effector*: any cell, organ, or structure with which an animal can respond to external or internal stimuli usually functions, along with a sensor and an integrator, as part of a homeostatic system

Species → Richness and Diversity

- *species richness* is the number of species present in a given community - *species diversity* is a weighted measure that incorporates a species' relative abundance - these terms are often used interchangeably

RG: How is population growth calculated?

- ∆N/∆t = (B-D) + (I-E)

RG: Define the three basic types of survivorship curves. Describe the characteristics of an organism that exhibits each type

- *survivorship curve*: a graph depicting the percentage of a population the survives at different ages • type 1 → survivorship throughout life is high and then drops drastically • type 2 → occurs in species where individuals have about the same probability of dying each year in life • type 3 → extremely high death rates for larvae but in high survival rates that make it past the risky time

Survivorship

- *survivorship*: the proportion of offspring produced that survive, on average, to a particular age - type 1 curve → survivorship through life is high, and most individuals approach the maximum life span of the species - type 2 curve → most individuals experience relatively constant survivorship over their lifetimes - type 3 curve → result from high death rates early in life, with high survivorship after maturity

RG: What is the difference between weather and climate?

- *weather*: the short-term atmospheric conditions of temperature, moisture, sunlight and wind at a specific time and place - *climate*: the prevailing, long-term weather conditions in a particular reason

MB: Deer are hosts of ticks but are not reservoirs of B. burgdorferi — their immune systems detect and kill the bacterium. But a tick with a prior bacterial infection can consume a blood meal from a deer and then bite and infect a human. The fitness effects of a deer on B. burgdorferi can be summarized as:

- + or - depending on whether the deer is the tick's last host

Q9: In a hypothetical population of 1000 frogs there exists a gene with two alleles. 280 of the frogs are homozygous dominant (DD), and 220 are homozygous recessive (dd). What is the frequency of allele d?

- 0.47 WORK d → √0.22 = 0.47

Q9: In a hypothetical population of 1000 frogs there exists a gene with two alleles. 280 of the frogs are homozygous dominant (DD), and 220 are homozygous recessive (dd). What is the frequency of heterozygotes in the population?

- 0.5 WORK 280/1000 = 0.28 → DD 220/1000 = 0.22 → dd 1 - (0.28 + 0.22) = 0.5

Q9: In a hypothetical population of 1000 frogs there exists a gene with two alleles. 280 of the frogs are homozygous dominant (DD), and 220 are homozygous recessive (dd). What is the frequency of allele D?

- 0.53 WORK 1 - 0.47 = 0.53 - have to account for D in homozygous dominant and heterozygous

Q10: Santa Cruz island is the largest of the six channel islands off of California's coast, and is entirely made up of conserved land and National Park administered land. The island is approximately 250 km^2 and is home to approximately 140 land bird, 11 mammal, 3 amphibian, and 5 reptile species. The next biggest island, Santa Rosa, is ~200 km^2 and is home to approximately 100 bird, 3 mammal, 2 amphibian, and 3 reptile species. What is the density of species on Santa Rosa Island?

- 0.54 WORK 108 species/ 200 km^2 = 0.54 s/km^2

RG: What factors control the rate of nutrient cycling?

- 1) abiotic conditions such as oxygen availability, temperature and precipitation - 2) the quality of the detritus as a nutrient source for the fungi, bacteria, and archaea that accomplish decomposition - 3) the abundance and diversity of detritivores present

Calculating Population Changes Over Time

- 1) if a population starts with 80 individuals and grows to 120 after 2 years, what is the population increase per year? - growth per capita: r = (∆N/∆t)/N1 - per capita growth rate = growth rate per individual WORK - the population has gained 40 individuals in two years → 40/2 = 20 individuals/year r = (20/1)/80 = 0.25 per capita growth

RG: What characteristics can be used to describe a community?

- 1) the total number of species - 2) the relative abundance and distribution of those species - 3) the sum of interactions among all species - 4) the physical attributes of the community

MB: Assume there are 200 MendAliens living on an island in my back yard. If my island has an area of 20 hectares, what is the population density of MendAliens in terms of MendAliens per hectare?

- 10 MendAliens per hectare • population density is calculated as population size divided by area • 200 MendAliens/ 20 hectares = 10 MendAliens per hectare

MB: A population is growing exponentially and its instantaneous growth rate (r) is 0.02. Would the number of individuals added to the population (rN) be greatest at a population size (N) of 20, 500 or 1000?

- 1000 • rN would be greatest at the highest N

Q10: Suppose researchers marked 800 turtles and later were able to trap a total of 300 individuals in that population, of which 150 were marked. What is the estimate for total population size?

- 1600 WORK (300/150) x 800 = 1600

MB: Suppose researchers marked 800 turtles and later were able to trap a total of 300 individuals in that population, of which 150 were marked. What is the estimate for total population size?

- 1600 WORK N = (300/150) x 800 N = 1600

Q10: Santa Cruz Island → Adult Fox Population 1993 - 1406 1997 - 1073 1999 - 527 2001 - 137 2006 - 204 2009 - 1150 2015 - 2170 What was the population density of foxes on Santa Cruz Island in 1999?

- 2.1 WORK 527 species/ 250 km^2 = 2.1

MB: You are doing a mark-recapture experiment to determine the population size of the MendAliens living on an island in my back yard. Initially, you catch and mark 130 MendAliens, which you then release. Next, you capture 90 MendAliens, of which 20 are marked. What is your estimate of the population size of MendAliens living on the island in my back yard?

- 585 • to get the population size N, multiply the number marked in the first catch, M1, by the total number caught in the second catch, C, and divide that by the number of marked recaptures in the second catch, M2 • (130/20) x 90 = 585

MB: Estimate total population size in a mark-recapture study in which 200 individuals were initially marked, and you recaptured 150 of which 50 were marked.

- 600 • this is a simple method for field biologists to determine rough population estimates

Q9: Foxes and skunks consume some of the same prey, although foxes are primarily diurnal and skunks are primarily nocturnal. Which graph best represents their respective niches?

- B

Q9: Use the following diagram of a hypothetical food web to answer the question(s) below. The arrows represent the transfer of energy between the various trophic levels. Which letter represents an organism that could be a producer?

- B

Q9: While traveling in Texas, you stumble across a snake with red, yellow, and black bands. You somehow remember that this could be a poisonous coral snake or a harmless milk snake, but you forget how to differentiate them because they both have similar colors and banding patterns. You wisely decide not to pick up the snake. What you don't realize, is that it was the harmless milk snake. What defense of the snake was successful in preventing you from grabbing the snake?

- Batesian mimicry

Q9: Which letter represents an organism that could only be a primary consumer?

- C

RG: Describe the global cycles for the following biogeochemical factors → water, nitrogen, phosphorus, and carbon

- Global Water Cycle: the movement of water among abiotic and biotic reservoirs in terrestrial and aquatic ecosystems - Global Nitrogen Cycle: the movement of nitrogen among abiotic and biotic reservoirs in terrestrial and aquatic ecosystems - Global Phosphorus Cycle: the movement of phosphorus among abiotic and biotic reservoirs in terrestrial and aquatic ecosystems - Global Carbon Cycle: the movement of carbon among abiotic and biotic reservoirs in terrestrial and aquatic ecosystems

Hardy-Weinberg Equilibrium Wrap Up

- Hardy-Weinberg equilibrium tests the null hypothesis that a population is not evolving - this is done through measuring the frequency of alleles in a population - if evolutionary factors such as natural selection are acting on a population, they will not be in HW equilibrium

Hardy-Weinberg is about probability

- Hardy-Weinberg is all about the probability that certain alleles will be passed down - genotypes: AA, Aa, aa - genotype frequencies: p^2, 2pq, q^2 - e.g. the frequency of the aa genotype is the probability of having both an 'a' sperm (probability q) and an 'a' egg (probability q) → q^2 - mathematically... the frequency of all genotypes is given by (p+q) (p+q) = 1 • (p+q) is the frequency of each type of egg and sperm • 1 for 100% of the population - simplified equation → p^2 + 2pq + q^2 = 1 - violations of Hardy-Weinberg are what interests us, especially in terms of helping us determine the mechanisms of change in a population - hypothesis: natural selection or some evolutionary process is affecting a particular trait in a population - Hardy-Weinberg functions are a null hypothesis

Mark-Recapture Example

- N = (C/R) x M • 1) capture and mark species (M) • 2) release and wait • 3) capture species again and count the total (C) and the number recaptured (R)

Hardy-Weinberg Conditions

- NO natural selection → differential survival or reproduction - NO migration - NO mutation - large population (NO genetic drift) - random mating

Separate Niches

- NO overlapping of niches, coexistence is possible

Q8: Use the accompanying diagram of Channel Islands, as well as MacArthur and Wilson's island biogeography principles, to answer the question(s) below: Which island would likely have the greatest species diversity?

- Santa Cruz (1)

Hardy-Weinberg Practice

- Using allele frequencies S = 0.84 and s = 0.16. Predict genotypes → SS, Ss, and ss p = 0.84 and q = 0.16 SS = p^2 → (0.84)^2 = 0.7056 Ss = 2pq → 2(0.84)(0.16) = 0.2688 ss - q^2 → (0.16)^2 = 0.0256 - allele frequencies → what fraction of the egg and sperm are dominant/recessive - genotype frequencies → what fraction of population is homozygous dominant or recessive or heterozygous

Community Dynamics

- a *disturbance*: any strong, short-lived disruption to a community that changes the distribution of living or non-living resources • i.e. forest fires, floods, and disease epidemics - a disturbance's impact is a function of three factors • 1) type of disturbance • 2) frequency of disturbance • 3) severity of disturbance - most communities experience a characteristic type of disturbance • in most cases, disturbances occur with a predictable frequency and severity • this is called a community's *disturbance regime* º i.e. prairie fires in the Midwest (common → happens every year)

MB: In 1983, a population of dark-eyed junco birds became established on the campus of the University of California, San Diego (UCSD), which is located many miles from the junco's normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. Males with more white in their tail are more likely to win aggressive interactions, and females prefer to mate with males with more white in their tails. Females have less white in their tails than do males and display it less often. (Pamela J. Yeh. 2004. Rapid evolution of a sexually selected trait following population establishment in a novel habitat. Evolution 58[1]:16674.) Refer to the paragraph on dark-eyed junco birds. The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of males from nearby mountain populations averaged 40—45% white. If this observed trait difference were due to a difference in the original colonizing population, it would most likely be due to __________.

- a founder effect

MB: What is the combination of resources used and conditions tolerated in the absence of competitors called?

- a fundamental niche • a fundamental niche is NOT influence by competitors

MB: Which of the following student-drawn niche models represents a species of lungfish that lives mostly in shallow water?

- a negative logistic graph shape • this niche model represents a species of lungfish that lives mostly in shallow water. the highest proportion of individuals occurs at depths of less than 3 meters, drops to 0.1 at 3 meters, and then to 0 at 6 meters.

RG: Explain the Hardy-Weinberg Principle

- a principle of population genetics stating that genotype frequencies in a large population do not change from generation to generation in the absence of evolutionary processes and nonrandom mating

RG: What factors influence distribution and abundance of organism?

- abiotic factors → temperature, light, pH - biotic factors → competition

MB: The range of Burmese pythons in Florida is expanding rapidly. List abiotic factors and biotic factors that might limit the range of pythons.

- abiotic → cold temperatures to the north and occurrence of deep seawater (Atlantic Ocean and Gulf of Mexico surrounding southern Florida) - biotic → increased predation on eggs or juveniles, competition for food, spread of disease, and occurrence of parasites

RG: How can diversity of species be described and/or measured in a community?

- abiotic → spatial hypotheses or energy hypotheses - biotic → ecological interactions hypotheses or evolutionary history hypotheses

MB: Newly hatched ticks do not harbor B. burgdorferi. Rather, they pick it up from certain hosts that are reservoirs of the bacterium. When a larval tick crawls onto a host, it may get groomed off and killed by the host, or it may feed successfully, in which case it may or may not then become infected with B. burgdorferi. Felicia Keesing and others measured the rate of tick feeding and infection on different hosts. What percentage of ticks on mice were infected with B. burgdorferi?

- about 45%

MB: Newly hatched ticks do not harbor B. burgdorferi. Rather, they pick it up from certain hosts that are reservoirs of the bacterium. When a larval tick crawls onto a host, it may get groomed off and killed by the host, or it may feed successfully, in which case it may or may not then become infected with B. burgdorferi. Felicia Keesing and others measured the rate of tick feeding and infection on different hosts. What percentage of ticks on opossums were groomed off and killed?

- about 95%

RG: How does energy move through an ecosystem? How efficient is this process?

- according to Likens and Bormann only about 45% of GPP went to NPP while the other 55% is used for cellular respiration or lost through heat

MB: Which of the following statements describes a negative feedback response?

- after a meal, blood sugar levels in the body rise; insulin is secreted to lower blood sugar levels • the actions of insulin reverse the internal conditions of high blood sugar levels in the body

The Pyramid of Productivity

- all ecosystems share a characteristic pattern • the total biomass produced per year is greatest at the lowest trophic level and declines at higher levels - this pattern occurs because most of the energy consumed is used for growth and reproduction • the amount of biomass produced at each subsequent trophic level must be less than the amount at the previous level (10% rule)

MB: Which of the following would be most significant in understanding the structure of an ecological community? 1) determining how many species are present overall 2) determining which particular species are present 3) determining the kinds of interactions that occur among organisms of different species 4) determining the relative abundance of species

- all of the above

TH: For a species to be called "invasive" it must: 1. be introduced to a new area 2. spread rapidly in this new area 3. compete with native species successfully

- all of the above • introduced to a new area • spread rapidly • compete with natives

MB: In the accompanying figure, which of the lines represents exponential growth?

- all the lines represent exponential growth

Q9: Evolution in a population of island iguanas can be caused by the following agent(s): genetic drift gene flow natural selection

- all three → genetic drift, gene flow, AND natural selection

MB: Which of the following actions is not a function of the epithelium?

- allows the internal environment to alter its conditions to match those of the external environment • the epithelium allows the internal environment to remain constant even if the external environment changes

RG: How do mutations impact evolution?

- although it is an effect, mutation is a slow process compared to selection, genetic drift and gene flow

MB: In the accompanying figure, which of the arrows represents the carrying capacity?

- arrow C

MB: White-footed mice occupy a broad ecological niche — they occur in most communities regardless of habitat quality. Many other species, like the opossum, are absent from low-quality forest fragments. Based on this information and the graph, propose a hypothesis to explain the observed relationship between increased forest fragmentation and increased incidence of Lyme disease.

- as forest fragmentation increases, species richness will *decline*. as species richness *declines*, white-footed mice will still *be present* in the populations (due to the species' *broad* niche), but species like opossums will *be absent* (due to their *narrow* niches). since mice *are* huge reservoirs of the Lyme bacterium and species like opossums *are not*, a greater percentage of animals present in forest fragments *will* host the Lyme bacterium. thus, the incidence of Lyme diseas ewill *increase*

Some Species have more influence than others on community structure

- biologist generally recognize two different types of such species • some have a "bottom-up" effect on community structure • others have a "top-down" effect - when abiotic factors such as amount of nutrients, sunlight, or water determine the abundance of primary producers, this is *bottom-up control* • particular species at the "bottom" of the food web can have a major effect on community structure, such as kelp in kelp forests or redwoods in redwood forest • these important primary producers are sometimes called "ecosystem engineers" because the provide physical structure that is habitat for many species • removal of ecosystem engineers can cause dramatic changes to community structure

Biotic Factors

- biotic ("living") factors-interactions with other organisms limit distributions - competition - reproductive requirements - parasitism - other interactions

TH: What affects the size of a population?

- births - deaths - immigration - emigration

MB: This niche model shows the range of latitudes tolerated by a species of palm tree today. Which of these niche models shows the predicted northern expansion of this species (shown in blue) due to climate change?

- blue line shifted more to the right than the green line • this niche model shows the predicted northern expansion of the palm tree species because the predicted curve (blue) is shifted to the right--toward higher latitudes--of the present-day curve (green).

MB: Which of the following statements comparing endotherms and ectotherms is correct?

- both endotherms and ectotherms exchange heat with the environment through convection, conduction, radiation, and evaporation

Q8: Why does it take 10 times more energy to grow a kilogram of beef than a kilogram of wheat?

- cattle only integrate 10% of their food into biomass

RG: How does natural selection violate the Hardy-Weinberg equilibrium?

- certain alleles are associated with the favored phenotype, they increase in frequency while the other alleles decrease in frequency

RG: Within a range, how are organisms distributed?

- clumped - random - uniform

MB: Epiphytic orchids grow harmlessly on their host trees, and derive their resources from the air and from rain, rather than from their host plant. Which of the following is the best description of this species interaction?

- commensalism

MB: An egret eats insects stirred up by grazing animals. Which of these terms applies to the relationship between the egret and the grazing animal?

- commensalism • in commensalism, one member of the species pair benefits and the other is unaffected; in this case the egret is getting a meal and the grazing animal is unaffected

Q9: Which of the communities in the figure has the lowest species richness?

- community 3

MB: How might genetic drift be important in a small population?

- it decreases genetic diversity via sampling error during mating • genetic drift is of large concern with populations of a small size because you are more likely to have mating between close relatives

RG: What is the general outcome of gene flow?

- it equalizes allele frequencies between the source population and the recipient population

Q8: Golden eagles, feral pigs, and insular carnivores: How exotic species turn native predators into prey by Roemer et al The California Channel Islands are a group of 8 islands located off the coast of southern California. 6 of the islands are inhabited by the endemic island fox. Island foxes are the largest native carnivore on the islands, feeding predominantly on mice, insects, and fruits. On 2 islands, Santa Cruz and Santa Rosa, the island spotted skunk co-occurs with the fox. Smaller in size, skunks are strict carnivores, feeding exclusively on mice and insects. Foxes are general diurnal, while skunks are nocturnal. Feral pigs are also found on Santa Cruz Island, where they have been present for over 150 years. The feral pigs are omnivores and feed on fruits, insects, and small animals (mice, lizards, etc.). The introduction of pigs to the Channel Islands provided an abundant food source for Golden Eagles and enabling the historically transient visitors to the islands to colonize them. Eagles feed on both foxes and young pigs. Exotic species and apex predators are important drivers of ecosystem change and have been increasingly recognized as major concerns in the conservation of terrestrial ecosystems. In cases where exotic species have caused biodiversity loss, their effects are typically manifested through direct species interactions in the form of predation, competition, or hybridization. The arrival of Golden Eagles in the islands, has corresponded with a crash in the populations of foxes. *Based on the background text, what kind of interspecific interactions are occurring between skunks and foxes?*

- competition

MB: Humans and sharks both eat fish. Which of these terms applies to the relationship between the human and the shark?

- competition • the human and the shark are both competing for a resource (fish)

MB: Which species interaction depends on prey density and effectiveness of prey defenses to determine the impact on the prey population?

- consumption

MB: Cystic fibrosis is a genetic disorder in homozygous recessive (ff) humans that typically significantly reduces life expectancy. Over time, we would expect the f allele frequency to ___________ for this trait

- decrease

Q10: Returning foxes to their pre-Eagle introduction population levels would have what effect on primary consumer populations?

- decrease

MB: Which of the following is the most predictable outcome of increased gene flow between two populations?

- decreased genetic difference between the two populations

What's a niche?

- definitions from different scientists • sum of habitat requirements needed for survival and reproduction • role a species plays in a community • biotic and abiotic factos - ways organisms respond to resources and other species found within the habitat - a niche is the organism's job and its workplace

TH: How do humans impact niches? What activities might influence this?

- deforestation - contamination - pollution

MB: An ecologist record 12 white-tailed deer, Odocoileous virginianus, per square kilometer in one woodlot and 20 per square kilometer in another woodlot. What was the ecologist comparing?

- density

Population Equations

- density = (N)/ area - ∆N = N2 - N1 = (B-D) + (I-E) - r = (∆N/∆t)/ (N1) - Nt = N1 (1+r)^t - r = per capita rate change - N1 = initial population - N2 = final population - B = births - D = deaths - I = immigration - E = emigration - t = time (use 1 if not specified, or "year 2 - year 1)

RG: What factors limit population growth?

- density-dependent and density-independent factors

MB: Why do populations grow more slowly as they approach their carrying capacity?

- density-dependent factors lead to fewer births and increased mortality

Q10: Why was the growth of the fox population on Santa Cruz Island started to level off during the last few years of available data?

- density-dependent factors lead to fewer births and increased mortality

RG: Give a few examples of how natural selection can lead to phenotype changes over time

- directional selection → changes the average value of a trait - stabilizing selection → reduces variation in a trait - disruptive selection → increases variation in a trait - balancing selection → maintains variation in a trait

MB: Why is Lyme disease on the rise? Lyme disease is caused by infections of the bacterium Borrelia burgdorferi which is transferred to humans via blood-sucking bites from the tick, Ixodes scapularis. Lyme disease can cause flu-like symptoms in the short term and more serious illnesses in the long term, if not treated. Why is Lyme disease on the rise in eastern North America? In relation to humans, B. burgdorferi is a/an ______ and the tick is a/an ______.

- endoparasite/ ectoparasite

MB: Which two terms apply to most mammals?

- endotherm and homeotherm • mammals generate heat internally and maintain a constant temperature

RG: Compare and Contrast the positive and negative aspects of endotherms and ectotherms

- endotherms • pros → maintain high body temps at all times, can be active in the winter and night, high levels of aerobic activity • cons → have to obtain a lot of energy - ectotherms • pros → thrive with lower intakes of food, can use a great proportion of their total energy intake to support production • cons → chemical reactions are temperature dependent, more vulnerable to predation in cold weather

MB: Compared to ectotherms, endothermic animals are likely to be at the greatest disadvantage in ______________

- environments with variable and limited food sources

MB: Panting of an overheated dog achieves cooling by ___________

- evaporation

MB: Which of these physical processes do not help a lizard increase its body temperature?

- evaporation • when water evaporates from a lizard's skin to become a gas, heat is pulled from the body of the lizard. however, evaporation cannot result in heat gain

MB: Which of the following statements is consistent with the principle of competitive exclusion?

- even a slight reproductive advantage will eventually lead to the elimination of the less well adapted of two competing species

Overlapping Niches

- every species has a unique niche, or set of survival requirements (food, temperature, water, pH, etc.) - competition occurs when one or more species overlap - too much overlap, the niche is no longer big enough for both species • very heavy competition leads to *competitive exclusion*: with this much competition eventually one species will be excluded from the niche • the competitively inferior species ultimately will go extinct

MB: Which of the following statements best summarizes evolution by natural selection as it is viewed today?

- evolution by natural selection is the differential survival and reproduction of the most-fit phenotypes

MB: Are Burmese pythons taking over Florida? Burmese pythons (Python molurus bivittatus), constricting snakes that can reach enormous sizes (up to 7 meters in length), are native to Southeast Asia but were released to southern Florida from the pet trade. Many other snakes occur naturally in this area. Are the introduced pythons a problem? Burmese pythons were first found in the wetlands of Everglades National Park in the 1980s, but only rarely. The graph shows what happened next. Most of the data are derived from chance encounters of pythons on roads (pythons are notoriously difficult to find). How would you describe the type of population growth in pythons from 2000 to 2008?

- exponential

Exponential Growth

- exponential growth curves are typically described as j-shaped - even through r is constant, exponential growth adds and increasing number of individuals as the total number of individuals, N, gets larger • if r = 0.02, and N = 1 billion, over 20 million individuals are added to the population in a year • if r = 0.02, and N = 100, just 2 individuals are added in a year

MB: Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the HardyWeinberg model?

- f(A1) = 0.9700, f(A2) = 0.0300

Fitness Trade-Offs

- fitness trade offs occur because every individual has a restricted amount of time and energy at its disposal — its resources are limited - in general, organisms with high fecundity tend to grow quickly, reach sexual maturity at a young age, and produce many small eggs or seeds - organisms with high survivorship tend to grow slowly, invest their energy and time in traits that reduce damage from enemies, and increase their own ability to compete for resources

Community Interactions Wrap Up

- fitness: the ability to survive and produce viable offspring - when species interact • positive (+) → species benefits • negative (-) → a species incurs a fitness cost • neutral (0) → no effect on fitness - competition negatively impacts both individuals • intraspecific = same species • interspecific = different species - overlap of niches leads to competition, this can lead to speciation

RG: Are the changes that result from genetic drift adaptive?

- genetic drift is random with respect to fitness — the changes in allele frequency that it produces are not adaptive

MB: How might genotype frequencies of alleles for body size change under directional selection?

- genotypes that represent larger individuals become more prevalent • directional selection is changing genotypes in a particular direction

RG: What are some of the potential biological effects of climate change?

- geographic range shifts - phenology shifts - adaptations - extinction - ocean acidification

Estimating Populations Example

- given → 200 red nuthatches initially caught, 150 second capture, and 50 recaptured N = (150/50) x 200 N = 600

Homeostasis

- goal → maintain equilibrium around a specific point or value known as a set point - change (aka perturbation) in environment - change is sensed → requires a sensor - an integrator determines whether a response is required - a response is generated by an effector to restore the set point - an ability to interact with, and respond to the environment is key

MB: How might gene flow be important in managing an endangered population?

- it increases genetic diversity by introducing alleles from one population into another • gene flow is the movement of alleles between populations

MB: An animal's inputs of energy and materials would exceed its outputs if ___________

- it is growing and increasing its mass

Q8: The competitive exclusion principle states that __________

- it is not possible for two species with the same niche to coexist in the same region

MB: Mutation is the only evolutionary mechanism that ___________

- it the ultimate source of variation in natural populations

Q8: Golden eagles, feral pigs, and insular carnivores: How exotic species turn native predators into prey by Roemer et al The California Channel Islands are a group of 8 islands located off the coast of southern California. 6 of the islands are inhabited by the endemic island fox. Island foxes are the largest native carnivore on the islands, feeding predominantly on mice, insects, and fruits. On 2 islands, Santa Cruz and Santa Rosa, the island spotted skunk co-occurs with the fox. Smaller in size, skunks are strict carnivores, feeding exclusively on mice and insects. Foxes are general diurnal, while skunks are nocturnal. Feral pigs are also found on Santa Cruz Island, where they have been present for over 150 years. The feral pigs are omnivores and feed on fruits, insects, and small animals (mice, lizards, etc.). The introduction of pigs to the Channel Islands provided an abundant food source for Golden Eagles and enabling the historically transient visitors to the islands to colonize them. Eagles feed on both foxes and young pigs. Exotic species and apex predators are important drivers of ecosystem change and have been increasingly recognized as major concerns in the conservation of terrestrial ecosystems. In cases where exotic species have caused biodiversity loss, their effects are typically manifested through direct species interactions in the form of predation, competition, or hybridization. The arrival of Golden Eagles in the islands, has corresponded with a crash in the populations of foxes. *The symbols +, -, and 0 are to be used to show the results of interactions between individuals and groups of individuals in the example that follows. The symbol + denotes a positive interaction, - denotes a negative interaction, and 0 denotes where individuals are not affected by interacting. The first symbol refers to the first organism mentioned. Match the organismal interaction with the appropriate symbols*

- golden eagle/ fox → +/- - fox/ skunk → 0/0 - golden eagle/ skunk → 0/+

RG: What factors influence population size?

- growth → births and immigration - decline → deaths and emigration

MB: How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria?

- he evaluated blood samples for malaria parasites and the presence of sickle cells - he expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected • Dr. Allison gathered blood samples from more than 5,000 children in East Africa. he analyzed the samples to identify malaria parasites and sickle cells. he found that children carrying the sickle cell character (or trait) had a lower parasite count, as if they were partially protected against malaria

MB: In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?

- he hypothesized that there was a connection between malaria and sickle cell disease • on the basis of this hypothesis, Dr. Allison predicted high frequencies of sickle cell disease only in areas where malaria is common

MB: The recessive allele that causes sickle cell anemia is harmful to homozygous individuals. What maintains the presence of this allele in population's gene pool?

- heterozygote advantage

RG: Why is it important for organisms to maintain homeostasis of their body temperature?

- homeostasis conditions inside the body allow molecules, cells, tissues, organs, and organ systems to function at optimal levels

MB: How does inbreeding alter genotype and allele frequencies?

- homozygotes increase in frequency in the population over generations • inbreeding increases homozygosity

RG: How is human activity changing these biogeochemical cycles?

- humans disturb the natural regulation of these biogeochemical cycles (erosion, carbon emissions, etc.)

RG: What organ is responsible for regulating temperature in humans?

- hypothalamus

RG: How can community structure be influence by producers? Consumers?

- if the loss of one can affect the entire food web from receiving nutrients - bottom-up or top-down community structures

RG: How does habitat size influence diversity of species? How does island size and location influence diversity of species?

- immigration rates should be higher on large islands close to mainlands because immigrants are more likely to find large islands that are close to shore - extinction rates should be higher on small islands because fewer resources are available to support large populations

MB: How does Dr. Allison's work provide an example of natural selection in humans?

- in areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles - in areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease • in different environments, natural selection favors different characteristics. in areas with malaria, the reproductive advantages of having one sickle cell allele (and some protection from malaria) kept the allele at high frequencies in the population. in areas without malaria, the reproductive disadvantage from sickle cell disease reduced the allele in populations

RG: What factors can lead to nonrandom mating?

- inbreeding - *sexual selection*: a type of natural selection that favors individuals with traits that increase their ability to obtain mates or choose good mates

Q8: How might climate change alter the figure arrows?

- increased evaporation from the ocean

MB: In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?

- individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population • people with one sickle cell allele are protected from malaria, but do not have sickle cell disease. protection from malaria comes at the cost of more sickle cell disease in the population

MB: Which component of a homeostatic system compares sensory information to a target value?

- integrator • an integrator sends instructions to an effector based on sensory information

MB: Which statement best describes the evolutionary significance of mutualism?

- interaction increases the survival and/or population growth rate(s) of mutualistic species

Using Niches to Analyze Competition

- interspecific competition occurs when the niches of two species overlap - in *symmetric competition*, each species experiences a roughly equal decrease in fitness when competing for a resource • both species may persist in the areas of overlap, even if in reduced numbers - *asymmetric competition* occurs when one species suffers a much greater fitness decline than the other • the outcome depends on the amount of overlap in niches

MB: Which of these terms applies to the relationship between a dog and a blood-sucking tick?

- parasitism • the tick benefits at the expense of the dog; the dog is the host and the tick is the parasite

MB: Interpret the model (orca, sea otter, sea urchin, kelp crab, kelp)

- kelp is the primary producer in this food web → true - this food web shows all of the species interactions in this ecological community → false - some of the energy and nutrients in the orca came from the kelp → true - the arrows should point down instead of up → false - sea otters are the primary consumers in this food web → false

Keystone Species Wrap Up

- keystone species have a much greater impact on the distribution and abundance of the surrounding species than its abundance and total biomass would suggest - disturbances of ecosystems can vary in severity - successions follow disturbances and allows for re-establishment of an ecosystem - species richness is the number of species present in a given area - species diversity is a weighted measure that incorporates a species' relative abundance

MB: Looking at the data in the accompanying figure, what can be said about survival and clutch size?

- large clutch size correlates with low survival

MB: Which of the following is the most important assumption for the mark-recapture method to estimate the size of wildlife populations?

- marked individuals have the same probability of being recaptured as unmarked individuals during the recapture phase

Q10: Which of the following is the most important assumption for the mark-recapture method to estimate the size of wildlife populations?

- marked individuals have the same probability of being recaptured as unmarked individuals during the recapture phase

TH: Which of the following are assumptions of the mark-recapture method of population size estimation?

- marking an individual has no effect on the probability it will be recaptured

MB: Genetic variation ____________

- must be present in a population before natural selection can act upon the population

TH: Name the five factors that influence evolution

- mutation - non-random mating - natural selection - genetic drift - gene flow/migration

TH: What is the most important factor in evolution?

- mutations

MB: Humans who have pets tend to be healthier than humans who do not have pets. Which of these terms applies to the relationship between a human and a pet?

- mutualism • in mutualism, both members of the species pair benefit; in this case the human is healthier and the pet is getting room and board

MB: Which evolutionary mechanism results in adaptation?

- natural selection • adaptation is the ability to reproduce and produce viable offspring in a particular environment. natural selection is the evolutionary mechanism that produces adaptations

How does the body respond to the environment?

- negative feedback → counteracts direction of the stimulus • body in homeostasis → variable throws body out of balance → body counteracts in response - positive feedback → maintains the direction of the stimulus

MB: What is the term used to describe the process shown in the panels in the accompanying figure, assuming Time 2 follows Time 1?

- niche differentiation

MB: Which assumption must be correct for a population to be in Hardy-Weinberg equilibrium for a specific gene?

- no genetic drift can affect allele frequencies for the gene • any condition that changes allele frequencies in the population represents a violation of the Hardy-Weinberg principle and means that the population will not be in Hardy-Weinberg equilibrium

MB: For biologists studying a large flatworm population in the lab, which Hardy-Weinberg condition is most difficult to meet?

- no mutation

Abiotic Factors and Niches

- no species lives everywhere on Earth - the suite of conditions a species can tolerate factor into an organism's niche - abiotic (non-living) factors explain only part of species distributions

MB: For a gene suspected of causing hypertension in humans, you observe the following genotype frequencies: A1A1 0.574; A1A2 0.339; A2A2 0.087. Is this gene in Hardy-Weinberg equilibrium? Why or why not? (Assume that a difference of three percent or more in any of the observed versus expected frequencies is statistically significant.)

- no. the expected genotype frequencies are A1A1 0.553; A1A2 0.381; A2A3 0.066 • the expected genotype frequencies are significantly different from those expected from the Hardy-Weinberg Principle

MB: A population is correctly defined as having which of the following characteristics? 1. inhabiting the same general area 2. belonging to the same species 3. possessing a constant and uniform density and dispersion

- only 1 and 2

RG: What factors influence where species live and the size of their populations?

- organisms tend to be adapted to a limited set of abiotic conditions (temperature, moisture, salinity, water depth, etc.) as well as biotic limitations (pollinators, protection, predators, etc.)

RG: What do p and q represent in the Hardy-Weinberg equation?

- p and q represent the frequency of alleles in a population • p → dominant • q → recessive - allele frequencies do not change over time

MB: In mammals such as a dog, thermoregulation is monitored by temperature receptors located through the body. If a mammal is cold, which of these responses would not help raise its temperature back to normal?

- panting • rapid panting increases evaporative cooling on the moist surfaces of the lungs, mouth, and extended tongue. this provides cooling of the body by removing heat from the blood circulating near these surfaces

Q10: What about the life history traits of pigs allowed them to thrive on the Channel Islands?

- pigs produce a large number of young per litter - adult pigs are too large to generally be eaten by Golden Eagles

MB: Most mammals are strict homeotherms. Elephants allow their body temperature to vary during the hottest parts of the day, meaning they are ____________

- poikilothermic

RG: How do mutations occur?

- point mutations - chromosome-level - lateral gene transfer

Geographic Distribution and Change in Population Size Wrap Up

- population density patterns vary - growth per capita: r = (∆N/∆t)/N1 - logistic population growth occurs when the population is limited by density-dependent factors - carrying capacity (K) is the max number of individuals that any habitat can support - density-independent factors also impact population size

Estimating Population Size Wrap Up

- population size is influence by births, deaths, immigration and emigration (I and E are usually negligible) - different ways to measure populations • counting → tally up individuals • random samples, transects • mark-recapture - fecundity: the number of female offspring produced by each female in a population

How do we look at populations?

- populations — individuals of a single species that occupy and reproduce in the same area - how do we define populations in nature? • boundaries º physical → rivers, ravines, highways º biological → gene flow, reproductive barriers º size → total number of individuals

Communities Change Over Time → Ecological Succession

- prairies (good examples) - long-term effects of fire on a tallgrass prairie community

MB: A human eats a deer. Which of these terms applies to the relationship between the human and the deer?

- predation • the human is the predator and the deer is the prey

MB: What is the main advantage of controlled burnings of forested areas? Controlled burnings _____.

- prevent the overgrowth of the underbrush

How does energy flow through ecosystems?

- primary producer → primary consumer → secondary consumer → tertiary consumer - energy dissipates as it flows through the system as heat - nutrients cycle through trophic levels - each level decomposes to provide nutrients to primary producers - *energy flow model*: energy moves through organisms in a form of biomass - a *primary producer (autotroph)*: an organism that can synthesize its own food from inorganic sources - consumers eat living organisms • primary consumers eat primary producers • secondary consumers eat primary consumers • tertiary consumers eat secondary consumers - *decomposers*, or detritivores, feed on detritus, the waste products, or dead remains of other organisms - organisms that obtain energy from the same type of source occupy the same trophic ("feeding") level

MB: A woman standing and watching the stars on a cool, calm night will lose most of her body heat by ____________

- radiation

MB: You observe a lizard sitting on a log on a sunny day. If the lizard is attempting to raise its body temperature by basking in the Sun, what mechanism of heat transfer is being employed?

- radiation

RG: What are some causes of genetic drift?

- random sampling • *founder effect*: the reduction of genetic variation that results when a small subset of a large population is used to establish a new colony • *bottleneck effect*: an extreme example of genetic drift that happens when the size of a population is severely reduced - removing individuals

MB: Which of the following student-drawn niche models for a species of butterfly represents the most narrow tolerance of temperature?

- red graph (steep curve at a high number of individuals) • this niche model represents the most narrow tolerance of temperature. at low temperatures, the number of individuals is very low. the number of individuals does not increase until moderate temperatures are reached, at which point the number of individuals is very high. as the temperature increases further, the number of individuals quickly decreases. this results in a graph line with a narrower peak than the other graphs shown

MB: Which term describes a steady state in which the internal conditions of an organism are kept within a narrow range without regard to the external conditions?

- regulatory homeostasis • regulatory homeostasis involves adjusting the internal conditions of an organism to stay within a narrow range without regard to the external conditions

Top-Down Influence on Community Structure

- removing top predators → observe this effect in action - when researchers remove the sea star (Pisaster ochraceous) from its habitat, mussels took over and drastically changed the rest of the community • examples where researchers can remove predators from ecosystems are rare - a *keystone species* has a greater impact on the distribution and abundance of the surrounding species than its abundance and total biomass would suggest • no matter if they become to great/ to small in number can have an effect

MB: Which component of a homeostatic system perceives changes in some parameter of the environment?

- sensor • a sensor perceives changes in some parameter of the environment

MB: The mark-recapture method would be best for sampling a population of ___________

- sharks • the mark-recapture method works best for active species whose individuals tend to be highly mobile

MB: Which of the following actions acts to warm a homeothermic body?

- shivering • shivering generates metabolic heat and warms the body

MB: Compare sickle cell disease and malaria

- sickle cell disease and malaria are both potentially lethal diseases • though malaria is an infectious disease and sickle cell disease is inherited, both can cause life-threatening conditions

RG: Is genetic drift more pronounce in large or small populations?

- small populations

MB: Interpret this student-drawn niche model of three species of flowering plants.

- soil moisture is the independent variable → true - the proportion of individuals is the dependent variable → true - species B and species C have a similar average tolerance for soil moisture → true - species C tolerates a broader range of soil moisture than species B → true - species C is more likely to live in a desert than species A → false

MB: Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. Which of the following terms best describes this situation?

- stabilizing selection

Succession

- succession is the recovery that follows a severe disturbance • *primary succession*: occurs when a disturbance removes the soil and its organisms, as well as the organisms that live above the soil surface • *secondary succession*: occurs when a disturbance removes some or all the organisms from an area but leaves the soil intact, including the seeds and microorganisms within º process ↳ 1) pioneering species ↳ 2) early successional community ↳ 3) mid-successional community ↳ 4) climax community

How Hardy-Weinberg Principle Relates to Gene Pool

- talks about populations as a whole

Q8: Golden eagles, feral pigs, and insular carnivores: How exotic species turn native predators into prey by Roemer et al The California Channel Islands are a group of 8 islands located off the coast of southern California. 6 of the islands are inhabited by the endemic island fox. Island foxes are the largest native carnivore on the islands, feeding predominantly on mice, insects, and fruits. On 2 islands, Santa Cruz and Santa Rosa, the island spotted skunk co-occurs with the fox. Smaller in size, skunks are strict carnivores, feeding exclusively on mice and insects. Foxes are general diurnal, while skunks are nocturnal. Feral pigs are also found on Santa Cruz Island, where they have been present for over 150 years. The feral pigs are omnivores and feed on fruits, insects, and small animals (mice, lizards, etc.). The introduction of pigs to the Channel Islands provided an abundant food source for Golden Eagles and enabling the historically transient visitors to the islands to colonize them. Eagles feed on both foxes and young pigs. Exotic species and apex predators are important drivers of ecosystem change and have been increasingly recognized as major concerns in the conservation of terrestrial ecosystems. In cases where exotic species have caused biodiversity loss, their effects are typically manifested through direct species interactions in the form of predation, competition, or hybridization. The arrival of Golden Eagles in the islands, has corresponded with a crash in the populations of foxes. *Which of the following food webs most accurately depicts the Santa Rosa Island community?*

- tertiary consumer = golden eagle → eats feral pig and island fox (dashed line between skunk because it could be eaten, but its rare) - secondary consumer = feral pig → eats Jerusalem crickets, manzanita, deer mice, sea fig, and fence lizard - secondary consumer = island fox → eats manzanita, deer mice, Jerusalem crickets, sea fig, and fence lizard - secondary consumer = spotted skunk → eats deer mice, Jerusalem crickets, and fence lizards - secondary consumer = fence lizard → eats Jerusalem crickets - primary consumer = deer mice → eats sea figs - primary consumer = Jerusalem crickets → eats sea fig and manzanita - primary producer = sea figs and manzanita

Q10: Foxes that escaped Golden Eagle predation tended to be more active at night compared to other foxes. If, under this selective pressure, island foxes become nocturnal what would this suggest about that trait?

- that there is an heritable trait associated with time of activity

RG: How does gene flow affect fitness in a population?

- the arrival/departure of alleles can increase, decrease, or have no effect on average fitness. movement of alleles between populations tends to reduce their genetic differences

Homeostasis Wrap Up

- the body maintains homeostasis of a variety of processes through positive and negative feedback • negative counteracts the stimulus • positive foes in the direction of stimulus - thermoregulation is an important example of a important variable where the body needs to maintain homeostasis - there are four mechanisms of heat exchange → conduction, convection, radiation, and evaporation - there are two types of strategies for heat sources • endotherm: produces enough heat to warm its own tissues • ectotherm: relies on heat from the environment - there are two types of strategies for body temperature ranges • homeotherms: keep body temperature constant • poikilotherms: allow body temperature to change depending on the environment

Specialization Avoids Competition

- the change in species' traits is called character displacement - character displacement enables species to exploit different resources and makes niche differentiation possible - evolution by natural selection towards separate niches - specialization into two separate niches = resource partitioning or niche differentiation

MB: Suppose you trap some fish in a lake, mark them, and release them. Every month for a year you re-trap a similar number of the fish and release them. You notice each month that the proportion of marked fish trapped is declining. Which of the following is a reasonable explanation for this observation?

- the fish do not have long lifespans so some of the marked fish are dying each month • this would be a reasonable explanation

MB: As N approaches K for a certain population, which of the following is predicted by the logistic equation?

- the growth rate will approach zero

MB: Interpret this niche model for three species of birds

- the independent variable is branch height → true - species B builds nests in the widest variety of branch heights → false - species A and species B both build the most nests in branches about 4.5 m high → true - all three species build nests in branches that are 6 m high → true - competition for nest space will increase the fitness of species B but decrease the fitness of species A → false - more competition for branch space occurs between species A and B than species B and C → true

MB: Why can't a female lizard have both high fecundity and high survival?

- the more energy the female devotes to offspring, the less can be devoted to her survival

Species Richness and Diversity

- the number of species is usually positively correlated with habitat size • larger habitats have more niches and should support higher number of species - however, islands in the ocean have smaller numbers of species than do areas of the same size on continents

MB: If a person has two normal copies of the hemoglobin allele, which statements are true?

- the person is homozygous at the hemoglobin locus - the person is susceptible to malaria • a person with two copies of any allele is homozygous. a person with two normal copies of the hemoglobin allele is more susceptible to malaria than someone with a sickle cell hemoglobin allele

MB: Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated

- the sickle cell allele will decrease in frequency • without malaria, selection for the sickle cell allele decreases. as a result, the frequency will likely decrease

RG: Why does Earth experience seasons?

- the tilt of the Earth is what causes seasons - the steeper the incline the less sun that area will receive - ex: in the Northern hemisphere during June they are tilted more towards the sun then the Southern hemisphere so we experience our summer

Fundamental vs. Realized Niche

- the weaker competitor should be able to persist in the area of non-overlap — that is, it may not live in all possible habitats - *fundamental niche*: is the total theoretical range of environmental conditions that a species can tolerate - *realized niche*: is the portion of the fundamental niche that a species actually occupies, given limiting factors such as competition with other species

Ecology Wrap Up

- there are different levels of ecological study that vary in their scope - abiotic factors are non-living factors that impact species distribution • e.g. temperature - biotic factors are living factors that impact species distribution • e.g. competition for food - about 10% of biomass is transferred between tropic levels - food chains and webs summarize energy flow through an ecosystem

MB: Which of the following it TRUE of species interactions?

- they can act as agents of natural selection

Q8: Which of the following is TRUE of species interactions?

- they can act as agents of natural selection

MB: How could such a pretty fish be such an ecological problem? The red lionfish, Pterois volitans, has beautiful red stripes, streaming fins, and a fearless disposition, and it is deadly. Native to the Pacific Ocean, the red lionfish was first discovered on coral reefs in the Bahamas in 1985. The species has spread to over 3 million square kilometers of the western Atlantic and Gulf of Mexico. Lionfish have a voracious appetite for native fish, are armed with venomous spines, and have no natural predators in their new range. Why are species like the lionfish considered "invasive"?

- they spread aggressively and displace native species

Is it possible to test if a population is evolving?

- to do so, we need to determine if allele or genotype frequencies are changing over time - we can test the null hypothesis that a population is NOT evolving by applying the Hardy-Weinberg principle • if you reject the null, evolution is occurring

Trophic interactions can also have extraordinary influence on niche availability and diversity

- trophic: different levels of species (in terms of energy)

MB: True or False? Organisms must maintain homeostasis because optimal enzyme activity is achieved within a very narrow range of conditions

- true • enzyme activity depends on conditions within a cell, such as temperature and pH, which must be kept within a certain narrow range

TH: Given the data in the table, which survivorship curve does Lacerta vivipara best resemble?

- type 2 • graph before answering and remember exponential y-axis

MB: What is the main reason that a person sitting on the beach with an air temperature of 15ºC loses heat less rapidly than when immersed in lake water at 15ºC?

- water conducts heat more efficiently than air does

MB: Which of the following is an example of negative feedback?

- when blood glucose concentration increases, the pancreas produces and releases the hormone insulin. insulin acts to decrease blood glucose. as blood glucose decreases, the rate of production and release of insulin decreases

Logistic Growth

- why the slowdown? • logistic growth (s-shape) = density dependent effects º disease, predation, competition º usually biotic • *carrying capacity (K)*: max number of individuals that any habitat can support - if a population of size N is below the carrying capacity, K, the population should continue to grow. specifically a populations growth rate should be proportional - equation: dN/dt = rN([K-N]/K)

Estimating Population Size

- why would we want to measure population size? - why • conservation → how many are left? • invasive species → how severe is the expansion? • economic → how many are available? • basic → how do things work? - how • counting → tally up all the individuals • random samples, transects • mark-recapture - its not feasible to count every individual in a population, so how do we do it? • sub-sampling → plots, transects, GIs, etc.

MB: Which of the following would increase the rate of heat exchange between an animal and its environment?

- wind blowing across the body surface

RG: Can evolution occur without mutations?

- without mutations, eventually there would be no variation for selection to act on and alleles that were not lost would become fixed