Quiz 4 Study Guide
Quiz 4 Study Guide Bios 207
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This 4 page Study Guide was uploaded by Cara Cahalan on Thursday April 7, 2016. The Study Guide belongs to Bios 207 at University of Nebraska Lincoln taught by in Spring 2016. Since its upload, it has received 10 views. For similar materials see Ecology and Evolution in Biology at University of Nebraska Lincoln.
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Date Created: 04/07/16
Quiz 4 Notes 2/29: Niches and Distribution Niche set of ecological and environmental features to which an organism is adapted Why are niches where there are? Kirtland’s Warbler breed in young jack pine forests, only in part of Michigan o Jack pines are widespread, but Warblers are not due to some differences between the habitats available and the habitats they actually use niche Abiotic factor not alive. Biotic factor alive. Northern edge of Saguaro cactus range is set by: prolonged freezing temperatures and increased elevation (more N and higher) What prevents S. balanoides living farther South? Competition and temperature (both) K is not the same everywhere! Varies in time and space Range maps: o Distributions tell us about evolutionary paths o Different branches on phylogeny due to geographical displacement between two species 3/2: Competition LotkaVolterra mode: d N1 N 1 o Species 1: dt =r max 1( ) K 1 Brakes due to intraspecific competition, now we need brakes for interspecific competition d N1 N 1 ∝12 2 o Species 2: =r max 1− − dt ( K 1 k2 ) Last portion reduce growth rate from interspecific competition brakes from the other species Competition coefficients, read as ‘the effects of species 2 on species 1 o At each point in time, species 2 slows the growth rate of species 1, lowering its population size Per capita growth rate: N 2 undant, at k N 1in order to persist must be some nonoverlap, ( ) must be > 0 o 0= cannot grow What happens if alphas are all=1 a1d 2 =k o All effects are the same Neutral coexistence2 species are identical in the way they compete with each other and within species, may occupy the same niche 2 species have identical intra/interspecific competition, null ease, everyone is the same. Competitive Exclusion Principle o Two species with identical niches cannot coexist indefinitely o One will (likely) be a better competitor (have larger alphas) and this have higher fitness and eventually exclude the other (classic view) o Except that sometimes they might be ~ equal (competitive equivalence generating neutral coexistence) 3/4: Character Displacement Population: population dynamics, the unit of evolution The competitive exclusion principle suggests that if these two finches had exactly the same niche, they could not coexist. 3/7: Communities Species evenness ratio of species similarity (abundance) through environment see different species more easily Higher Shannon diversity right o Add concentration of more things that are more equal o Don’t need to calculate Straight line everything is at the same abundance One dot higher than the rest dominant species is present o Why do these patterns emerge? Warbler niches different feeding niches in trees o Dividing up territory, reduce competition o L/V coefficients are <iKiK Rulecoexist, divide world (inter < intra) Axis space different in space, insect types, temperature, biotic risk (predation) Food chain and trophic levels o Primary producer primary consumer 2 consumer 3 consumer o Plant (autotroph) herbivore carnivore Food web: o Mean trophic chain length? Count chains from start to finish Arrow total: 20/4 (levels) =5 pathways (lot of diversity in chain length) o Omnivore doesn’t have a single trophic level for consumption o Cannibalism overlapping circles, eat same species, easier on larger levels Rule of 10 only about 10% passes to the next level, ~90% loss at each trophic level heat into environment, waste Level has biggest bottleneck in flow of energy? Producers (1,000,000 10,000) Which food item takes most sunlight to make? Tuna Food chain length: ecosystem productivity o Straight line: no relationship Variation in trophic levels (in lake depends on lake volume) 3.9: Keystone Species and Trophic Cascades Direct interaction: solid arrow () Indirect interaction: dotted arrow (>) Trophic cascade: o Carnivore reduced herbivore increased primary producer reduced o Carnivore has an indirect positive effect on primary producer Keystones: o Large effect on community composition relative to biomass, loss of species has LARGE effect o Often top predators o Keystone species slow the pace of competitive exclusion Focal figure: sea star is a keystone species o Keystone has high impact due to position in food chain o Dominant species high impact due to abundance Is the bison a keystone or a dominant species? Keystone Ecosystem engineers: species that modify the habitat (i.e. beavers making dams) o For prairie: prairie dogs, they burrow and build mounds and change vegetation Interactions: o Tropic cascade o Trophic facilitation o Keystone species o Dominant species o Ecosystem engineers 3.11 Predators and Parasites Figure suggests that predators: o Can eat most of their prey o Predator growth depends on prey availability o Predator death depends on prey availability o Prey growth depends on predator abundance o All of the above Cycle comes from an interaction of lynx bseing regulated by hare, and hare being regulated by both lynx together Wolves on Isle Royale: RedQueen effect again o Predators eat prey predator population grows prey population declines predator population declines prey population grows repeat Generalist predators: o Take anything they can o Connected to many other species Specialist predators: o Take a limited number of things that they are good at taking o Connected to only a few species 3.14 Island Biogeography What changed as you add area? o Number of niches o Food chain length o Presence of keystone species o Inclusion of rare species o All of the above Fewer birds species are present on smaller islands farther away than number of species on islands that are larger and closer to the mainland o Is the speciesarea curve affected by isolation? YES Theory of island biogeography: o 1. Origin no species and no extinction o 2. Add species into the geography extinction increases (extinction rate) o 3. Species pool decreases immigration rate increases (fewer things so greater chance a new species will be introduced o 5. Equilibrium point At 6 extinction > immigration At 7 extinction < immigration o Extinction and immigration curves When species number increases, extinction of species increases and immigration rates decrease When species number decreases, extinction of species decreases and immigration rates increase o Equilibrium point: try and reach equilibrium point if moved away How can the theory of island biogeography explain speciesarea curve? o If extinctions decrease with area o If immigration increases with area, easier to find more area How can the theory of island biogeography explain isolationdiversity effects? o If extinction increase with isolation o If immigration decreases with isolation, farther to travel so less organisms can make it How would you test this theory? o Destroy all species on an island Near island: recovers more quickly due to higher immigration rates Far island: recovery takes longer Main themes for this section: o Competition (intra and inter) Competitive exclusion principle o Niches, distribution o Competition coefficients (LotkaVolterra model) o Theory of island biogeography: Extinction curve Immigration curve Equilibrium point Species pool Rate of immigration or extinction o Food chains/webs o Keystone species, engineers o Trophic cascades o Character displacement
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