Exam 3 Study Guide
Exam 3 Study Guide 301
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This 7 page Study Guide was uploaded by Morgan Deal on Sunday November 1, 2015. The Study Guide belongs to 301 at University of South Carolina taught by Dr. April South in Summer 2015. Since its upload, it has received 44 views. For similar materials see Ecology and Evolution in Biology at University of South Carolina.
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Date Created: 11/01/15
EXAM 3 STUDY GUIDE Chapter 13: Population Dynamics Over Space and Time Population fluctuations- happens with ALL populations o Large organisms- fluctuate less due to large surface area to volume ratio; allows for homeostasis in adverse conditions o Small organisms- reproduce faster and respond faster to changing environmental conditions o Age structure fluctuations- high numbers in any one age group usually corresponds with high birth or death rates in that year o Overshoot- population exceeds carrying capacity (k), usually due to a reduction in k because of decrease in resources o Die-off- decrease in population density following an overshoot Cyclic behavior of populations- most populations have an inherent pattern of regular oscillations over time o Can occur over large geographic areas between related species o Reasons- may be due to storage of nutrients or delays in moving from one life stage to the next Delayed density dependence- density dependence occurs based on population density at some time in the past dN Nt−τ o =rN(1− ) dt k o rτ < .37 no oscillations o .37 < rτ < 1.57 damped oscillations (magnitude of oscillations decreases over time) o rτ > 1.57 stable limit cycle (large oscillations over time) Extinction- population ceases to exist o Reasons- small populations are more susceptible; usually due to lack of resources, natural disasters, or human activity o Deterministic model- does not account for variation in population growth rates o Stochastic model- accounts for variation in population growth rates Demographic stochasticity- due to random variations among individuals Environmental stochasticity- due to environmental conditions Habitat quality o Habitat fragmentation- breaking up a habitat into smaller habitats o Basic metapopulation model- assumes that all patches of habitat are of equal quality Each occupied patch has the same subpopulation size Each subpopulation supplies the same number of dispersers to other patches e p−¿1− c o Rescue effect- dispersers supplement declining populations to prevent extinction Chapter 14: Predation and Herbivory Both can have dramatic effects on species abundance o Invasive species- introduced species that grows rapidly and negatively affects other species o Types of predators Parasitoids- predators whose larvae eat prey from the inside out Mesopredators- smaller carnivores that typically eat herbivores Top predators- bigger carnivores that are at the top of the food chain Population cycles o Stable cycles can occur when environment is complex so predators cannot easily find prey o Lotka-Volterra model- incorporates oscillations in abundance of predator and prey populations dN Growth of Prey = =rN−cNP dt rN = exponential growth rate of prey population cNP = loss of individuals due to predation dr Growth of predator population = dt=acNP−mP acNP = birth rate mP = death rate Prey population is stable when dN/dt = 0 Predator population is stable when dP/dt = 0 o Equilibrium isocline- population of one species causes the population of another to be stable Prey at equilibrium when P = r/c Predators at equilibrium when N = m/ac o Functional responses- relationship between prey density and predator consumption Type I- predator rate of consumption increases until satisfied (uncommon) Type II- predator rate of consumption decreases as prey density decreases, then plateaus Any prey density increase causes consumption to slow Type III- low, rapid, slowing prey consumption under low, moderate and high prey density Most common in the wild o Prey can find places to hide o Predators have less practice finding prey but can develop search image (helps locate and capture food) o Predators may exhibit prey switching o Numerical response- change in number of predators due to population growth or movement Evolution of defenses o Behavioral- prey will use alarm calls, spatial avoidance and activity reduction o Chemical Warning coloration (aposematism)- distastefulness evolves in association with conspicuous patters or colors Mimicry- selection favors palatable species that look like unpalatable species Batesian mimicry- palatable species evolve similar coloration to unpalatable species Mullerian mimicry- several unpalatable species evolve similar warning colorations Plants- sticky compounds, resins, alkaloids o Structural defenses- anything that reduces a predator’s ability to capture, attack, or handle prey Crypsis- camouflage o Costs- can reduce growth, reproduction, and development Behavioral defenses have many trade-offs with food gathering, etc. Mechanical defenses are energetically costly Hunting strategies o Active hunting- predator spends most of the time moving around looking for prey o Ambush (sit and wait) hunting- predator lies in wait for prey to pass Chapter 15: Parasitism and Infectious Diseases Types o Ectoparasites- live on the outside of organisms and feed on bodily fluids through puncturing the skin Little difficulty moving from host to host High exposure to external environment, low exposure to immune system of host Organisms- arthropods (ticks, fleas, etc.), nematodes, leeches o Endoparasites- live on the inside of organisms inside of cells (intracellular) or in body cavities (intercellular) Difficult to move between hosts Low exposure to external environment, high exposure to host immune system Organisms- bacteria, fungi, viruses, prions, helminths Infection ability o Modes of transmission Horizontal transmission- passed between organisms that are not parent/offspring Vertical transmission- passed from parent to offspring Vector- transmits a parasite between hosts o Ability of parasite to jump between hosts o Host immune response o Existence of reservoir species Parasite/host dynamics- similar to predator/prey dynamics, except parasites do not usually kill the host o S-I-R Model- assumes no new births of susceptible individuals and that once resistance is gained, it is retained S = number of individuals susceptible to a pathogen I = number of individuals infected R = number of individuals developing resistance g = rate of transmission via contact between individuals GRAB b = rate of recovery and development of immunity B for b-cells of immune system!! Probability of contact between susceptible and infected individuals = S(I) Rate of infection between susceptible and infected individuals = S(I)(g) Rate of recovery of infected individuals = I(b) Ratio of new infections to recoveries = reproductive ratio of parasite S(I)(g) rateof infection = I(b) rateof recovery R0>1 infection will spread R0<1 infection fails to spread Evolution of defenses- hosts can produce immune responses, develop antibacterial or antifungal compounds or utilize biochemical responses Evolution of offenses- parasites can alter behavior of host to ensure survival and increase probability of infection Chapter 16: Competition Resource limitation o Interspecific competition- between members of different species o Intraspecific competition- between members of the same species o Resources- things that organisms use/consume that cause population increases when abundant Renewable- are constantly regenerated Nonrenewable- are not regenerated o Leibig’s Law of the Minimum- the most limiting resource prevents the population from increasing further If 2 species compete for the same limiting resource, the species that can drive abundance of the other species to the lowest level will survive Assumes that each resource has an independent effect on population o Competition exclusion principle- 2 species cannot coexist when they are limited by the same resource One species will be superior in either gaining the resource or surviving when it is scarce o Competition by related species is intense because they have similar uses for resources Selection will favor different habitat usage o Competition between non-related species can be intense if species are using a similar resource Models o Competition coefficients- convert relative population numbers from one species to another o Competition based on single resource d N 1=r N (1− N 1αN 2) dt 1 1 K 1 d N N −βN 2=r N 1− 2 1 dt 2 2( K 2 ) N =K −α N N Species 1 stable when 1 1 2 OR when 1 is 0 Species 2 stable when N 2K −β2 1 OR when N2 is 0 o Isoclines- population size at which no growth is experienced Species 1 N =0 N =K When 2 , 1 1 N =0 K 1 When 1 , N 2 α Species 2 When N1=0 , N 2K 2 K 2 When N 20 , N 1 β o Competition based on multiple resources- 2 species can coexist only when 1 is better at persisting at low levels of different resources Factors that affect competition o Disturbances- natural disasters o Predation and herbivory o Abiotic conditions Types of competition o Exploitative competition- individuals consume a resource to make it less abundant so others cannot use it o Interference competition- competitors defend resources Aggressive interactions Allelopathy- use of chemicals to harm competitors o Apparent competition- 2 species have a negative effect on each other through a enemy
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