Unit 4
What are the parameters for the SIR model?
d= natural death rate of the host alpha= parasite-induced death rate lambda= force of infection =rate at which susceptibles become infected b= birth rate (independent of infection class) gamma= recovery rate (eg due to immune response)
What are some different types of biomes?
*biomes are determined by precipitation and temperature -desert -tropical rainforest: rain always falling, high plant productivity, low nutrient acquisition for soil because of rain run-off→ buttressed roots are needed (shallow rooted, large horizontal surface area) -tropical seasonal forest: drop leaves in the dry season -tundra: very short growing season; dwarf shrubs and trees protected by snow in winter -boreal forest: small leaves heat up less leading to lower transpiration demand; small diameter tracheids (cells used for transport) less prone to embolism than large diameter vessel elements of angiosperms -grassland -savanna -temperate forest/ rainforest: a lot of moisture, westerly winds (30 to 60 degree latitude)
What is the coriolis effect? How does it affect the planet?
*coriolis effect combined with cells rotating near surface and higher altitudes cause prevailing wind patterns across world -trade 0 to 30 -westerlies 30 to 60 -polar easterlies at extremes *The Coriolis effect is a deflection of moving objects when they are viewed in a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right. The Coriolis effect is caused by the rotation of the Earth and the inertia of the mass experiencing the effect. Because the Earth completes only one rotation per day, the Coriolis force is quite small, and its effects generally become noticeable only for motions occurring over large distances and long periods of time, such as large-scale movement of air in the atmosphere or water in the ocean.
Why might the capture rate per predator NOT be directly proportional to prey density?
-Predation rate per predator as a function of prey density -Type 1: capture rate per predator directly proportional to prey density--> this was proven false/ unrealistic -Type 2: search and handling time (chase, capture consumption) are separate -Type 3: Acceleration in response to increase prey density
Ellesemere Island
-80 degree N latitude -farthest north island in Canada -moth takes 17 years to grow feeding on tussock grass
Why are mountaintops cooler and how do they make rain?
-Abiatic cooling: change in pressure causes air to cool→ cannot hold as much moisture -warm, moist air is forced upwards and thus cooling occurs -if the dew point (100% relative humidity) is reached → rain falls -little precipitation on other side of the mountain due to rainshadows -Rainshadows: the mountains block the passage of rain-producing weather systems and cast a "shadow" of dryness behind them. -the incoming warm and moist air is drawn by the prevailing winds towards the top of the mountains, where it condenses and precipitates before it crosses the top. The air, without much moisture left, advances behind the mountains, thus creating a drier side called the "rain shadow".
What are biogeographic realms? what are ecoregions?
-Biogeographic realms are geographically isolated (by oceans or desert or major mountain ranges) and act as barriers to gene flow -Biome types are shared among biogeographic realms and are determined by climate and soil (same biome can be in Canada and Siberia with different species composition) -Ecoregions are subdivisions of biogeographic realms and are not isolated by barriers to dispersal (particular biome in particular location with same species composition)
What is exploitation efficiency? What is growth efficiency? What is ecological efficiency?
-Exploitation efficiency: amount of food ingested divided by the amount of prey production -Growth efficiency: The efficiency of conversion of ingested food to unit of body substance ("growth efficiency") is an index measure of food fuel efficiency in animals. It's a rough scale of how much of the food ingested is converted into growth in the animal's mass. It can be used to compare the growth efficiency as measured by the weight gain of different animals from consuming a given quantity of food relative to its size. -Ecological efficiency: describes the efficiency with which energy is transferred from one trophic level to the next. It is determined by a combination of efficiencies relating to organismic resource acquisition and assimilation in an ecosystem. This value is normally 10% → total biomass of each trophic level is about 1/10th that of the level it feeds on *difference between primary and secondary productivity
What is a trophic structure?
-Flow of energy between different levels -primary producers: acquire energy from environment/ autotrophs -herbivores come next/ primary consumers -secondary consumers: predators that eat herbivores -lose energy each time flow from one level to the next→ respiration uses up some energy/ parts of plants / herbivores indigestible -parasites: predators for all the levels -decomposers eat dead/ dying material→ break down organic material to cycle the trophic structure again
What kind of interactions exist between species?
-If effect of species 1 on species 2 is positive and effect of species 2 on species 1 is positive, then MUTUALISM. (+,+) -If effect of species 1 on species 2 is positive and effect of species 2 on species 1 is negative, then NATURAL PREDATORS (predator/ prey, grazer/ plant, parasite/ host.) (+,-) -If effect of species 1 on species 2 is neutral and effect of species 2 on species 1 is negative, then AMMENSALISM--> example is animal steps on grass. (0,-) -If effect of species 1 on species 2 is negative and effect of species 2 on species 1 is negative, then COMPETITION. (-,-)
What are the types of natural enemies?
-If there is one victim and it is killed, then it is a parasitoid. -If there is one victim and it is not killed, it is a parasite. -If there are many victims and one is killed, it is a predator. -If there are many victims and not killed, it is a grazer (considered not killing because the grass grows back).
Oscillatory dynamics= epidemics
-Infection → immunity or death→ lower density of susceptibles (S) -dI/dt drops below 0, so incidence of disease declines -number of susceptibles increases due to birth and immigration -when S> N T, then disease can spread again (new epidemic)
What did the iron fertilization experiment show?
-Iron is a limiting resource in oceans -there is a decrease of CO2 as the ocean uses iron -iron is used in chlorophyll synthesis and a cofactor to mediate metabolic reactions, photosynthesis, and the electron transport chain
What are the formulas for change in population size? What is per capita growth rate? For a given unit of time?
-N is population size -pgr is per capita growth rate -pgr=0 means no change in population size -pgr> 0 means exponential growth -pgr<0 means decline to extinction of population
What is the species area relationship?
-S=cAz -log (S)=log(c) +zlog(A) -number of species (S) can be expressed as a function of Area (A) This relationship can be due to the idea that as we increase the area, we are incorporating more habitats, adaptations, speciation events, biogeographical realms.
How can ocean currents affect terrestrial climate?
-The ocean currents are driven mainly by trade winds and prevailing westerlies, tides, Earth's rotation (Coriolis effect), and sun (solar radiation), and local topography. -The current patterns affect temperature of the landmasses. One possible cause for this phenomenon is due to Thermohaline circulation. It is the global ocean conveyor belt. The evaporation from warm surface water and the influx of fresh water from glaciers lead to saltier water sinks. Heat released to atmosphere warms Europe. If we look at the warmest places, there are warm currents. ***-strong current brings warm water from Caribbean and goes next to Europe so even though it is at high latitude it has a very mild climate→ influence water, nutrients, temp
What are discrete generations?
-They are species in which generations do not overlap (parents die before offspring show up). -wavelength is a finite rate of increase. -if lambda =1, no change in population size -if greater than 1, increase in population size -step wise function (staircase)
What is the routes of transmission of ?
-Vertical (parent to offspring); usually through the egg, seeds -typically from mother only -Horizontal -from outside environment -example: squid and Vibrio bacteria (bioluminescent) -Mixture of vertical and horizontal -acquire from mother, other individuals, or external environment -example: gut flora of termites
How do microbursts regulate species diversity?
-a microburst is a tornado -this extreme weather will destroy habitats and disturb the stability -rare orchids began to appear after a microburst because they could only germinate with drastic changes in the environment -human impact decreases the amount of diversity by protecting again forest fires
Rainshadow of rockies?
-a rainshadow is a dry area on the side of the mountain away from the wind; The mountains block the passage of rain-producing weather systems and cast a "shadow" of dryness behind them. -short grass prairie (farther west-drier) -tall grass prairie (farther east wetter)
Mutualism and defensive associations
-acacia is type of tree with sharp thorns -swollen thorns protect against herbivores -ants live inside swollen thorns and provide additional protection -vibration will induce ant arousal; sting -tree provides food and protected environment
What are different escape modes?
-air -brush -brush and grass -grass -When we compare the before (no cover) and the after (brush added), we see an increase in bird species that escape to brush, but not other species.
What is the trophic structure of the Eel River?
-algae -chironomids (midge larvae) -small fish (fry) -predatory insects -trout
Which organisms need a larger breadth of temperature toleration?
-animals at higher latitudes, animals on land, and animals in the Northern Hemisphere; if we look at a graph that has latitude on the x-axis and temperature tolerance on the y-axis, we see that the breadth or difference of temperature tolerance increases as we increase with latitude
Why/ how do these inverted pyramids exist? Could we have an inverted pyramid with productivity?
-ants are smaller than trees→ the productivity of one tree is much larger -absolute #'s don't make sense -difference in generation time could have an effect -there are not as many phytoplankton because the zooplankton consumed them
How do changes in the environment influence species richness?
-as we go to larger scales, there can be changes to altitude, precipitation, temperature, soil type -environmental factors (gradient) influences # of species that we find -an increase in elevation (just like altitude) will change species diversity
What is the species accumulation curve?
-at local scale as we increase area we are likely to capture more species -at small area, we expect certain # of species -there is a measurement error so 2 lines -estimated richness versus observed richness: estimated richness curve is higher than the observed richness curve
What is a model?
-attempt to capture essential characteristics and facilitate a deeper understanding -specific models versus general models
What is continuous population growth?
-b and d: birth rate and death rate -simplified into r (intrinsic rate of increase) -if more individuals are born than die, then population will increase -if we asked how long it would take for the population to double (Nt=2No), t= ln(2)/r
What is biomass? What is gross and net productivity? What is net primary productivity?
-biomass: mass of organisms (usually a whole trophic level) per unit area in the ecosystem -productivity is ratio of output to input and it includes gross and net. -gross: rate of energy flow into a trophic level -net: rate of production of new biomass by a trophic level -net primary productivity (NPP)= gross primary productivity (from photosynthesis)-respiration= rate of production of plant biomass (photosynthetic efficiency is small in comparison to amount of sun that hits the Earth) **factors that influence NPP includes precipitation, and residual variation like temperature and amount of nitrogen
Tropical deciduous forest
-biome where leaves are dropped in dry season (and not when it is cold) -Latin America/ Panama
What are the types of controls on population size?
-bottom up control: different trophic levels; populations controlled by # of resources they have (at the levels below them) -trophic cascades (top down control): consumers depress the trophic level on which they feed, and this indirectly increases the next lower trophic level. -green world hypothesis: if everything is bottom up control, then most plants would be eaten by herbivores→ then not a lot of plants; but in reality we see a lot of plants. Thus the herbivores are not using plants to full advantage--> herbivore populations are being regulated by levels above (through top-down control from predators)
What is a community? What is an ecosystem?
-community: all of the species in an area that can potentially interact -ecosystem: community and physical environment, which includes soil, minerals, amount of sun/rain, climatic disturbances, etc.
How can population size be controlled by density-independent and density-dependent mechanisms?
-density independent: per capita growth rate (pgr) does not depend on population density→ major weather catastrophe -density dependent: per capita reduction in survival or fertility depends on population density→ run out of food -population regulation: negative feedback slows population growth as density increases→ have less food decrease birth rate
What is the energy production difference between poikliotherms and homeotherms?
-diff species have different metabolic rate -poikilotherm uses 30 X less energy→ production efficiency is much higher for P -homeotherms better use their environment but it is not helping to transmit energy from primary producers up the trophic model
What do the species area curves look like on local versus global scales?
-different factors affect # species -as area increases in yard, more birds (but not linear due to factors at local scale) -species may be uncommon/ hard to find -at higher levels, as increase area we are incorporating additional habitats (more adaptions/ speciation events) -more biogeographical realms that isolate species
What is the equation for logistic growth? What is the equation for discrete logistic?
-discrete logistic is a completely deterministic relationship. -the graph will change when r is low versus high--> -at low r values, there is a smooth growth and reach carrying capacity→ hit equilibrium -if r is large, there are oscillations. The population will overshoot carrying capacity, compensate
How do disturbances affect species diversity?
-disturbances for the most part increase species diversity -there is a happy medium though (low disturbance will have low species diversity while very high disturbance will lead to lower species diversity) -We can think of the example of staghorn coral--> it can be oppressive to an environment (superior competitor) but is held in check by disturbance so other species of coral can survive.
Temperate deciduous forest?
-drop leaves in winter 1. less transpiration demand (less stomata, less moisture to potentially lose) 2. lower risk of freeze induced embolism (cavitation) in vessels of angiosperms
How quickly can an equilibrium point be reached?
-equilibrium points can be reached very quickly if we fumigate the mangrove tree and time how long it takes for insects to repopulate
How is symbiotic mutualism a mechanism of evolutionary innovation and adaptive radiation?
-eukaryotic cell (mitochondria) -photosynthesis in eukaryotes (chloroplast) -colonization of land by plants (mycorrhizae→ symbiotic fungi; acquire minerals) -nitrogen fixation by plants (rhizobia-various alpha and beta-proteobacteria) -animal life at deep sea vents (chemoautrophic life systems) -use of nutrient-limited resources (xylem, phloem) by animals
Mutualism and fruit dispersal
-fruit encourages other species to eat the fruit because they want the species to spread their seeds -species poop out the seeds and spread the seeds
What are leaf cutter ants and what types of symbiosis is at play?
-fungus grows on leaves -nitrogen-fixation: due to bacteria associated/symbiosis with fungi -high nitrogen in colonies (and even higher within each individual) and low in leaves
How does vegetation influence climate?
-greenhouse effect: greenhouse gases (CO2, Methane, N2O, ozone) collect in the Earth's atmosphere. These gases allow the sun to shine on the Earth's surface but trap the heat that reflects back to the atmosphere--> act like glass walls of a greenhouse. Keeps the Earth warm! When humans cut down forests, they release a lot of CO2 (trees contain a lot of carbon). Less temp fluctuation *the warming of Earth that results from retention of heat in its atmosphere= greenhouse effect -desertification: deserts will spread on edges of Sahara. Overgrazing leads to the vegetation not growing back. When vegetation does not grow back, this will alter the climate because when wind blows on it, there is a positive feedback loop to increase in desert even more
How would demographics influence population growth?
-if growth rate depends on age (age structure), then we need to know age structure to predict overall population dynamics; when we compare Afghanistan with the US, we see that Af's pyramid is bottom heavy which means all the youngsters are going to reproduce and contribute to an increased pgr!
What affects island biogeography?
-immigration rate and extinction rate affect the island biogeography -species arise on the island by immigrating from the mainland -more species means more competition -there can be an equilibrium point between extinction and immigration rate -Affect immigration rate: distance between island and mainland -Affect extinction rate: size of island (smaller island means more likely for populations to go extinct) *The idea of islands applies to other areas like mountain tops, lakes, ponds, and nature reserves
What is the difference between temperate and tropical forests?
-in temperate forests, nutrients are limited (but there are more nutrients in the soil). By looking at the depth of the root mass, we see it is quite deep and there is a lot of white fungus. -in tropical forests there are not deep roots with white fungus. The roots are surface level. -tropical forests are also phosphorus limited.
What is the spread of vertically transmitted microbes?
-increased host survival and reproduction (mutualism) -metabolic benefit -organelles: mitochondria and chloroplasts -defense against natural enemies -Reproductive manipulation (modification) -feminization: turn presumptive male hosts into females (wolbachia is transferred via cytoplasm and sperm does not have cytoplasm) -male-killing: kill ~all of the male offspring -parthogenesis induction: get asexual, all-female lineages -cytoplasmic incompatibility: infected males sterilize uninfected females (attempt to keep transferring the symbiont) -mixture of vertical and horizontal transmission. Only way for purely parasitic types to spread
Consequences of SIR model for spread of disease
-infectious disease more likely to invade and persist in large populations more likely to retain a disease -diseases with high transmission rate have lower threshold densities. Nt large for influenza, small for measles -Vaccination programs: don't need to vaccinate everybody to eradicate disease just need to reduce number of susceptible so that S< N T
What kind of competition exists between species? (specifically what are the mechanisms of reciprocal negative interactions between species)
-interspecific competition has negative effects on both species -exploitation: both trying to utilize the same resource→ competition -interference: utilize same resource and directly interact; (gulls chase away smaller birds) -intraguild: same trophic level and prey on one another→ one group of fish preys on the juveniles of other species -apparent: 2 competing species share same predator→ competing to NOT get preyed on
What are the characteristics of parasites?
-intimate association with host, live on (ectoparasites) or in (endoparasites) host -host= habitat and food -cause harm, but not immediate death, to host -use one host species per stage of life stage of the parasite. Parasites with complex life cycles can have intermediate and definitive hosts. Sexual reproduction of parasites occurs in the definitive host -often highly host specific→ tremendous diversity of parasites
What are keystone species? Keystone predators?
-keystone species have a major effect on the overall community structure (greater than would be expected based on their abundance or biomass) -they are rare and sometimes we only see their effect when they are removed -keystone predator can be seen when we look at starfish that prey on mussels (and the subsequent starfish removal experiment) -kangaroo rats are also a keystone predator that prey on seeds (when we remove the rats, the habitat changes from desert to grassland)
Marine Biogeographic realms
-major realms include Atlantic -isolated communities within that
How is chlorophyll a's absorption spectrum used as a measure of NPP? What are the factors that can predict NPP?
-material in chloroplasts that absorb light has specific absorption spectrum -NPP looks at photosynthetic capabilities so chlorophyll a is a good gauge. if we look at a map of the world, we can see that high absorbance of the light at the wavelengths that correspond to the pigment chlorophyll a means a higher NPP. -2 peaks (not absorbing in green range→ why plants are green) -how much of chlorophyll a is absorbed in different parts of the world? -summer northern hemisphere ( a lot of photosynthesis is occurring ) -autumn decrease in chlorophyll a in northern; high in tropics -high concentrations along coastal regions -estimate NPP -NPP is usually (gC/m^2/yr) -Amazon, region in tropics (northern Africa very low due to little rain) -best predictor of NPP is annual precipitation -residual variation: variation that is not explained by precipitation -the variance is explained by temperature -as we increase temp. there will be more productivity -at temps lower than 0 C, very low! -in terrestrial environments the amount of nitrogen is also a predictor of photosynthetic abilities
Sonoran Desert, AZ
-mild, wet winters -summer monsoons -many plant growth forms -high biological diversity
Examples of the LV model at work?
-mites -snowshoe hare and lynx -this type of modeling system can be used when we study predator prey species that have the one match up. the organism has to have only one prey that it is being eaten by
What is the SIR model for directly transmitted microparasites?
-modeling based on numbers of hosts in three categories, not on total number of parasites
How can growth rate potentially vary based on population density?
-pgr=0 → no change in population size -pgr>0 → exponential growth N t+1> Nt -pgr<0→ decline to extinction of population N t+1< Nt
Harbor seal
-phocine distemper virus spread 1. local spread and die out 2. spatial spread 3. global die out
What is the typical lake food chain?
-phytoplankton photosynthesizing -zoo -planktivorous fish -piscivourous fish -disturbances in chain can affect the environment -when fish are absent the water becomes turbid (phytoplankton populations overgrow because nothing eats them) -if we add piscivourous fish back then lakes will become clean
What is a polar cell? Ferrel cell? Hadley cell?
-polar cell is in the polar region; polar easterlies occur here -ferrel cell: prevailing westerlies occur -hadley cell: trade winds occur here; 2 hadley cells meet at the equator
What is a population? What is population ecology?
-population: individuals of a species within a given area -population ecology: spatial and temporal dynamics of population density
Prickly cactus and gorse
-prickly cactus: when introduced in Australia they multiplied a lot. -the moth was introduced to Australia→ within 2 years the moths had changed the landscape by wiping out the cactus -currently it is hide and seek -example of gorse can be found in CA; it is a prickly, invasive plant that excludes other species of plants -spider mite preys on the gorse
What are primary and secondary consumers? What is primary and secondary productivity?
-primary consumer: -secondary consumer: -primary productivity: production of chemical energy -Secondary productivity: amount of biomass created at these higher trophic levels
Rainforest
-rain always falling -good productivity of plants -a lot of leaching of nutrients from the soil because of rain run-off
How can parasites affect their prey?
-reduce host fitness (survival and fertility)= major selective factor→ keeps population below the carrying capacity -regulate host populations, keeping N< K -mediate interactions between other species (e.g., affect outcome of interspecific competition) -affect sexual selection (females prefer unparasitized or resistant males) -trophic cascades (bush lupine, ghost moth, nematode) Think: Reduce Regular Meds After/ affect Training
What is resource overlap?
-resource overlap can be a measure of the similarity between organisms -they are trying to limit similarity -different pigeons utilize different fruit sizes -larger birds eat larger fruits -2 species utilize similar fruit sizes -only 1 or the other group lives on one island (they can't coexist in same environment) -competitive exclusion principle!
How do we avoid similarity?
-resource partitioning (niche partitioning)--> behavioral (the warblers will each take advantage of a part of the tree) -character displacement--> evolution -niche expansion
Why is biodiversity (species richness) important?
-respond to changing conditions (buffer) -allows for pollinator services -technology -medicine Think: respond always to Megan
What are the important variables of symbiosis?
-route of infection: maternal, horizontal, mixture -effects on host: -parasitism: mutualism continuum -contingency of fitness effect -Duration of the association -less than 1 generation to millions of generations -Mechanisms -location of symbionts in host body: intracellular, between cells, in specialized organ or in other tissues, within gut lumen, external -how cells are invaded (e.g., secretion systems) -how symbiont affects host fitness
What are the different types of evolution of mutualism between hosts and their symbionts? WHAT BENEFITS MUST OCCUR FOR MUTUALISM TO EXIST?
-short-term (<1 generation): partner-fidelity feedback -cooperation directed by specific individual -individual A directs benefits to a specific individual (B) that will some time later provide benefits to A→ Positive feedback cycle -metabolic complementarity -provide defense against natural enemies -long- term (>1 generation): correlation in fitness between genetic elements that undergo co-transmission -increase in fitness of host leads to increase in fitness of maternally transmitted symbiont
Mutualism and cleaning (ectoparasites removal)
-small fish live in coral reefs -set up cleaning station -eat ectoparasites that live on other fish -basically bringing them food
Boreal Forest
-small leaves heat up less leading to lower transpiration demand -small diameter tracheids (cells used for transport) less prone to embolism than large diameter vessel elements of angiosperms
Better reserve design?
-small versus large circle: large circle based on species area curve (increase area, increase species); there will be lower extinction rate, larger population, more habitats, and organisms can only survive in a certain size range -one large versus 4 small: large circle because larger area, it will mean more interactions and there can be different types of environments -4 small spaced closely together versus 4 small spaced less close together: tightly packed is better because more immigration between reserves so populations are stable -3 small linear versus 3 in triangle: 3 in triangle because more potential immigration between reserves -2 small or 2 small with corridor: corridor facilitates immigration
How do Darwin's finches exhibit character displacement?
-small, medium and large beaked finches -distribution of species will have same beak size if they are NOT found together. If they are together, then the size will be different→ no overlap of characteristics.
Bubonic Plague
-spatial spread of plague within Europe
What are stable cycles? What is chaos?
-stable cycles: deterministic -chaos: aperiodic oscillations; sensitivity to inititial conditions
What is nutrient cycling?
-the movement and exchange of matter back into the production of living matter--> this is mainly done after animals die and detrivores and composers break down the organisms -primary producers are nutrient limited (atmospheric nitrogen, for example, is abundant but hard to be taken up by many organisms -some plants (legumes) have evolved symbiosis with nitrogen fixing bacteria
What are the latitudinal gradients of diversity?
-there are more species in tropics than there are in temperate regions -there are the most butterfly species near the equator and they decrease the further we get from the equator -this pattern holds true for almost all groups of organisms
What are upwelling zones?
-there is a limit of nutrients in the oceans as well -in a map, the water appears green along the coast -there is an increase in the growth of producers here because nutrient rich waters that come from the cold depths of the oceans "upwell"
What are the polar easterlies? What are the prevailing westerlies? What are tradewinds?
-trade 0 to 30--> Hadley cells (2 hadley cells meet at the equator) -westerlies 30 to 60--> Ferrel cells -polar easterlies at extremes--> polar cells
Examples of top-down trophic cascade control and bottom up control?
-trophic cascade (top down control): -sea urchins prey on kelp; sea otters prey on urchins -Shark fishing has cascading effects -humans hunt shark. Sharks prey on ray species. Rays prey on scallops -example of bottom up control--> increased production results in greater productivity at all trophic levels
Tundra
-very short growing season -dwarf shrubs and trees protected by snow in winter
Mohave Desert, CA
-winter rains, few succulents or trees
Why are there more species in the tropics?
1. Historical reasons -regular glaciation periods occurred -glaciers meant less precipitation -Amazonian Refugia: more pockets of tropical forests (isolation means higher likelihood of speciation) 2. Climatic stability--> Less variation in temperature in the tropics 3. Biotic interactions→ Specialized species existence -predators and pathogens help to regulate the best competitors so that one species does not overpower an entire habitat) -large spacing of tree species because of parasite interactions 4. Latitudinal Gradients: range of temperatures is small in tropics -there are no seasons or temperature fluctuations -if organisms can survive/adapt to changes in seasons then they can survive range of latitudes (this reason does not necessarily show that there are MORE species in tropics, but rather that there is a DIFFERENCE of species in tropics versus temperate) 5. Productivity: more energy/ productivity allows for more species -higher NPP supports more biomass (doesn't necessarily mean more species diversity though) * Think: Historically, Climatic Biology LaGs Productively; How Come Boys Like Pussy?
Workshop paper that looked at red grouse and nematodes: 1. General question in the paper? 2. What is the host and what is the parasite? 3. How were the grouse experimentally manipulated? 4. What were the controls? 5. What was the key finding of the paper? 6. Interpret the results and conclusions in light of the original hypothesis? 7. Discuss the relative merits of natural (like this experiment) versus planned experiments.
1. Is the population cycling due to nematodes? 2. host=red grouse and parasite = nematode 3. Levamisole hydrochloride to treat for nematode parasite: -grouse caught at night in early spring when formed mating pairs -dazzled with strong quartz halogen lamp while roosting -caught in net -treated -bird marked with tag -subsequent monitoring -show that tagged and treated birds remained in their territories and had improved breeding 4. Untreated (natural level of infection) 5. -Parasitic nematodes were necessary for the cyclic declines in abundance that were observed in the grouse populations -population cycles in red grouse are the result of a single trophic interaction between a parasite and its host -parasites both sufficient and necessary in causing cycles in these populations -intrinsic mechanisms do not need to be evoked as a cause of cyclic fluctuations in grouse abundance 6. High worm→ breeding decreases→ population decreases Less nematode→ breeding increases→ population increases (grouse) More nematodes! 7. Natural has unlimited # of trial subjects; save money; uncontrolled :( while planned--> need to recreate correct # of trial subjects, expensive, control of varialbes
What is ecological allometry?
1. Lifespan as a function of body mass in animals (as mass increases, lifespan increases) 2. Intrinsic rate of increase (r) as a function of body mass (small organisms have fast growth rate --> small r value)
What influences chaos in biological systems? How can a deterministic relationship between generations cause chaotic fluctuations in the population?
1. based on deterministic functional relationship 2. negative feedback system 3. endless, aperiodic oscillations 4. sensitivity to initial conditions 5. unpredictable long-term dynamics because we can't determine the exact starting conditions.
Workshop paper on communities, ecosystems, and conservation: 1. what observation motivated this study? 2. What is the question being asked? 3. What island groups were being compared and how did they differ in otter populations? 4. Why are there more urchins in deeper water? 5. How does presence of kelp affect density of barnacles and mussels? 6. What are some larger community-level effects of otters? 7. In the Hairston paper, what are the trophic levels addressed in the paper? 8. If a trophic level is resource limited, is it near its carrying capacity (K)? 9. Which trophic levels are resource limited? 10. Which trophic levels are not resource limited? Which hypothesis does this concept reflect? 11. If a trophic level is not resource limited, what other ways could they be limited? 12. What is controlling the herbivore population? 13. Which trophic levels have the most competition?
1. oil spill banished kelp and the possible destruction of kelp and sea grass due to overgrazing of sea urchins 2. Do sea otters affect the ecology of the ocean? Are they the primary causes of the differences on the island? 3. Rat island had less otters and Near Island had more otters. 4. sea otters don't go deep to prey 5. less kelp means more barnacles and mussels; there is less kelp on the Near islands (because there are more otters) which means there is less barnacles and mussels while Rat has more otters and thus less urchins and more kelp 6. otter is the keystone species so they have a wide influence (more kelp means more seals)--> interconnectedness of food webs 7. they looked at decomposers, herbivores, producers, carnviores 8. yes 9. decomposers, producers, and carnivores are resource limited 10. herbivores are not resource limited which reflects the green world hypothesis (there is still more than enough green vegetation that is not being taken advantage of) 11. they can still be limited by predators, weather, herbivores, catastrophes, territoriality, and interspecific competition 12. predators 13. carnivores, decomposers, producers
What is the importance of regulating the abundance of prey? How can predators influence the community structure?
1.Biological control by natural enemies 2.Top down control/ trophic cascades
What is the competitive exclusion principle?
2 species cannot coexist indefinitely on the same limiting resource
What is the solstice? How does it lead to seasonal variation?
A solstice is an astronomical event that occurs twice each year as the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere. The solstices, together with the equinoxes, are connected with the seasons. At the solstices, the Sun stands still in declination; that is, the seasonal movement of the Sun's path (as seen from Earth) comes to a stop before reversing direction. At latitudes in the temperate zone, the summer solstice marks the day when the sun appears highest in the sky. However, in the tropics, the sun appears directly overhead (called the subsolar point) some days (or even months) before the solstice and again after the solstice, which means the subsolar point occurs twice each year.
Climatic Variation
Atmospheric circulations patterns can be influenced by a lot of things. * see web -latitudinal climate belts -latitudinal temperature gradient and coriolis effect -plate tectonics/ erosion -distribution of continents/ mountains/ topography -local rainfall and temperature patterns -maritime versus continental climates -ocean currents -orbit around sun/ tilted axis -seasonal variation in climate
What is the equinox?
Day when daytime and nighttime are of equal durations. An equinox occurs when the plane of Earth's equator passes through the center of the sun. At that instant, the the tilt of Earth's axis neither inclines away from nor towards the sun. The 2 annual equinoxes are the only times when the subsolar point—the place on Earth's surface where the center of the Sun is exactly overhead—is on the Equator, and, conversely, the Sun is at zenith over the Equator.
How does el Nino affect the ocean currents and the amount of precipitation?
Every few years there is a sporadic pattern of the ocean currents reversing (for 6 mo to year the waters flow west to east and then switch). This changes the amount of precipitation. El Nino usually causes droughts (as seen in Darwin's finches paper)
Mutualism and pollination
Ex/orchids and euglossine bees -bees are collecting fragrances -phylogeny: a line is an interaction between the 2 species. -mutualistic interactions have been maintained Ex/ figs and fig wasps -figs are considered keystone species -fig species can be obligate (they HAVE to be pollinated by the wasps)
What is the temperate rainforest?
Found in the pacific northwest. There is a lot of moisture, and westerly winds.
What are the components of the environment?
In a species' environment, there are both physical and biological components. -The physical (abiotic) components include conditions (pressure, pH, salinity) and resources. -The biological components include interspecific and intraspecific interactions. Interspecific interactions are between species and intraspecific interactions are within a species and include competition, mutualism, social situation, group dynamics, and reproduction.
What is island biogeography? Does it only apply to islands?
Island biogeography is a determinant of species richness (compare # of species on island versus mainland). It does not only apply to islands→ also applies to tops of mountains, lakes, ponds, and nature reserves.
Why is it dry at 30 degrees latitude? Why is it so wet at the equator?
It is dry at 30 degrees latitude because of the subtropical jet. Dry air warms up and becomes even drier with less moisture making it unlikely for rain → deserts occur It is wet at the equator because of the ITCZ where 2 Hadley cells come together and force warm moist air up so it cools at higher altitudes (adiabatic cooling due to change in pressures) and because cool air can't hold as much moisture, precipitation occurs
What is chaparral vegetation?
It is found in mediterranean climates/ mild latitudes like Southern CA. There are evergreens which are highly defended/ slow decomposition/ rapid regrowth. There are hot, dry summers. Nutrients are released and there is no competition for light or water.
What is thermohaline circulation?
It is the global ocean conveyor belt. The evaporation from warm surface water and the influx of fresh water from glaciers lead to saltier water sinks. Heat released to atmosphere warms Europe. If we look at the warmest places, there are warm currents. -Deep ocean currents are density-driven and differ from surface currents in scale, speed, and energy. Water density is affected by the temperature, salinity (saltiness), and depth of the water. The colder and saltier the ocean water, the denser it is. The greater the density differences between different layers in the water column, the greater the mixing and circulation. Density differences in ocean water contribute to a global-scale circulation system, also called the global conveyor belt. -The global conveyor belt includes both surface and deep ocean currents that circulate the globe in a 1,000-year cycle. The global conveyor belt's circulation is the result of two simultaneous processes: warm surface currents carrying less dense water away from the Equator toward the poles, and cold deep ocean currents carrying denser water away from the poles toward the Equator. The ocean's global circulation system plays a key role in distributing heat energy, regulating weather and climate, and cycling vital nutrients and gases.
What is the logistic equation for the continuous growth model?
K=carrying capacity (max # individuals that can be sustained in particular environment) -if population is very small, the growth is very close to rmax -as pop grows then pgr decreases until we reach carrying capacity -growth rate will be negative if we go above carrying capacity
Microparasites versus macroparasites?
Microparasites: -multiplies directly in host (many generations from a single infection) -small -short infection -many per infected host -viruses -bacteria -protozoa (some) -fungi (some) Macroparasites: -completes < 1 generation per infection -large -persistent (chronic infection) -few per infected host -helminths (roundworms, flatworms) -fleas, ticks, lice -mistletoe, indian pipe -lamprey
What does it mean if a trophic level is nutrient limited?
Primary producers are nutrient limited which means that even though the atmosphere has an abundance of nitrogen, it is hard for the organisms to take it up. For this reason, some plants have evolved symbiosis with nitrogen-fixing bacteria.
What are rainshadows in relation to mountains?
Rainshadow is a shadow on the other side of mountain that does not receive any rain.
Examples symbiotic and not symbiotic
Symbiotic and mutualistic: human gut microbiota; plants and mycorrhizal -symbiotic and neutral (commensal) are lichens growing on tree bark -symbiotic and harmful are pathogenic microbial infections -not symbiotic and mutualistic are plants and pollinators -not symbiotic and neutral (commensal) are all kinds of interactions -not symbiotic and harmful are predators
What is the intertropical convergence zone? (ITCZ)
The Intertropical Convergence Zone (ITCZ), known as the doldrums, is the area encircling the earth near the equator where the northeast and southeast trade winds come together. Seasonal weather occurs at regions where ITCZ are.
What is the Lotka-Volterra Model?
The Lotka-Volterra model explains cycling patterns seen in predator-prey populations. We recognize that predator species occurs at lower densities (on a graph they are the lower curve with lower amplitude while the prey occur at higher densities). At some point the predator population will have a negative impact on prey--> the impact, though, is not going to be instantaneous. -The graph has time on the x-axis and N (# of prey) on the y-axis These cycles might occur in the wild when the populations of predators and prey rely on one another (lynx and hare). -based on a logistic model of population growth--> The logistic-model of population growth includes a density-dependent component (within the parentheses) that reflects the impact of intraspecific competition on survival and reproduction.
What are allee effects? What could cause it?
The allee effect is that at low population densities, there is low pgr. Pgr will increase with N at low densities. -it occurs in small or sparse populations Mechanisms that could cause the allee effect include... -mate finding -detection and defense against predators -pack hunting (most important in small populations)
What is the compartment model?
The compartment model shows high turnover versus low turnover. -phytoplankton fix a certain amount of material, which has a high turnover -zooplankton's turnover is slower (it puts more into its compartment)
What is an equilibrium point? What factors influence the equilibrium point in island biogeography?
The equilibrium point is the absolute number of species on the island. Factors include: immigration and extinction rate -Affect immigration rate: distance between island and mainland -Affect extinction rate: size of island (smaller island means more likely for populations to go extinct) -When will the equilibrium point be shifted to the right versus left? -if we had a graph that showed curves for near island versus far island --> the FAR island will have an equilibrium point shifted to the left (less immigration so less species) while a near island will have more species and thus an equilibrium point shifted to the right -if we had a graph that showed a small island versus a large island, extinction will have a larger effect on a small island size so the equilibrium point is shifted to the left; while a large island will not be affected as much by extinction rate so it will be shifted to the right
Association between the # of nest eggs and the amount of predation on eggs?
The higher the proportion of nests with eggs, the more predation on eggs. -increased foraging activity and nest predation (per nest) where more nests contain eggs
How are habitat complexity and species diversity related?
The more complex the habitat, the more species diversity there is. We can think of this in terms of large trees versus small shrubs.
What is exponential growth?
There is a large slope and rate of increase. Populations grow exponentially under ideal conditions (a lot of resources/ unlimited resources and a small population). Exponential growth of a population occurs at relatively low population densities. We would find this after a major catastrophe or colonization. Exponential growth cannot persist for very long.
What are buttressed roots?
They are common in tropical trees. They provide mechanical support. They are shallow rooted, covering a large horizontal area for nutrient acquisition.
What are the life zone concepts?
They characterize vegetation types on the basis of physical features. These include elevation, temperature, precipitation, soil, etc.
How does temperature vary across the globe? Across the year?
To understand temperature variance across the globe and across the year, we need to understand equinoxes and solstices. -Mean Temperatures get colder as we go from low to high latitudes -high latitudes have more seasonality -seasonal variation increases on land than on water -Northern hemisphere has greater seasonal variation (because there is more land in northern hemisphere than southern) -these fluctuations are due to uneven input of solar radiation, which is caused by the shape of Earth and by the orientation of the axis around which it spins relative to Earth's orbit around the sun. The tilt of the Earth causes different latitudes to receive their greatest solar energy input at different times during the yearly orbit, in a yearly cycle of solstice and equinox.
What is the difference between climate and weather?
Weather is what happens day to day. Climate is the overall, long-term trends. It includes temperature, precipitation, and wind.
What is mutualism?
association is beneficial/ positive for both partners; not necessarily symbiotic
How can we predict biomes ?
based on precipitation and temperatures; there is a graph that shows at the lowest temperature and lowest precipitation, we see the tundra. At the highest temperature and highest precipitation we see the tropical rainforest.
Interspecific interactions
between species
Dynamics of SIR model
dI/dt> 0 for disease to spread lambda=force of infection Beta= transmission rate per infected host S= density of susceptibles for spread of the disease. For an emerging disease, S=N, so this is the threshold population density (N T) for invasion
What is the carbon/ nitrogen ratio for herbivores?
herbivores have 10:1 ratio of carbon to nitrogen so they have to consume extra plants to get the nitrogen they need.
What is the great Basin desert?
high elevation, cold winters, short growing season
Intraspecific interactions
interactions within a species; competition, mutualism, social situation, group dynamics, reproduction
What is the Lotka- Volterra competition equation?
predator-prey equations; there is a competition coefficient
What is the parasitism continuum for mutualism?
see chart -there is parasitism, commensalism, and mutualism. -Fleeting parasitism includes seed-eating birds, cleaner cheaters, and pollinator cheaters. -Fleeting mutualism includes fruit-eating birds, cleaner fish, and plants and pollinators. -Typical parasites are long-lasting but less than 1 generation. -Long-lasting but less than 1 generation mutualism includes mycorrhizae and ants and acadias. -Many generations, dependent on co-transmission parasitism include wolbachia and plant viruses. -Many generations dependent on co-transmission mutualism include wolbachia, buchera, cellular organelles. bark beetles and fungi, leaf-cutter ants and fungi, endophytic fungi, termites and protozoa
What is symbiosis?
species living in close and long-term association; not necessarily mutualistic
Ecology
study of distribution and abundance of organisms and their interactions with the environment