Exam 3 Study GuideExam 3 covers lectures 12-16 (Chapters 14-17)Lectures 12, 13, and part of 14: Chapter 14—Predation and HerbivoryTypes of interactionsAmensalism- no effect for 1, negative effect for 2 Commensalism-no effect for 1, positive effect for 2Competition-negative effect for both speciesMutualism-beneficial for both speciesConsumer-Resource Interactions- consumers abound (Predator/Prey, Parasitoid/Host, Virus/Host)-Predator/Prey- short and casual, high deathPlant/Herbivore-short and casual, low deathParasitoid/Host-long and close, high deathParasite/Host-long and close, low deathTerms associated with these terms (for example: symbiosis: interaction between two different organisms living in close physical association, typically to the advantage of both., herbivore: plant eatingcarnivore: meat eaterminer: decomposer. leaf minors, plant pests,etc)Classification of Consumer-Resource Interactions (fig 14.2 6th edition, and figure from Wiki)Effects of predators on Prey abundance(lizard & spiders on Caribbean Island) ^ predators v pray introduced species(snakes in Guam) negative effect on other speciesparasitoids(California Red scale insect & wasp) limit the abundance of preymesopredators- relatively small carnivores that consume herbivores (e.g., coyotes, weasels, feral catsTop predators: predators that typically consume both herbivores and predators (e.g., mountain lions, wolves, sharks).Effects of herbivores examples with fencing(deer enclosure) less herbivory, more plant growthCyclamen(mites ate strawberry field) removed predator, greater effect on plants and predatory mites Other examples of consumers limiting populations- sea urchin and algae (When researchers removed sea urchins from a rocky shore habitat, the biomass of algae increased.Algal composition also changed; only unpalatable algae species persisted with urchins, whereas without urchins palatable species dominated.)Population cycling—examplesSnowshoe Hare and Lynx inducing in the lab: Gause’s protists, Huffaker’s mites(Stable predator-prey population cycles can be achieved when the environment is complex so that predators cannot easily find prey.)Direct and indirect interactions-Direct: energy/interaction from the immediately consumed plant/animal (ex wolf:elk)Indirect: energy/interaction from secondary consumed plant/animal(ex wolf: dogwood)Herbivore-Plant: Folivore, frugivore, granivore(grazers, browsers)Predator-Prey: Insectivore, piscivore, avivore(carnivore)Resources—limiting, logistic equation• Any substance or factor that is both consumed by an organism and supports increased population growth rates as its availability increases– Consumed, availability decreases– Used for maintenance and growth– Reduced availability reduces population growthLimiting- A resource whose available quantity cannot meet a population’s requirement for itLogistic equation- dN/dt =r0*N[1-(N/K)]Lotka-volterra predator-prey model: a model of predator-prey interactions that incorporates oscillationsin predator and prey populations and shows predator numbers lagging behind those of their prey.Growth of prey populations depends on the growth rate of a prey population (rN) and the rate ofindividuals killed by predators (cNP) or growth of predator populations depends on growth rate of predator populations (acNP) minus the rate of predator death (mP) Equations: or Terms: N = number of preyP = number of predatorsc = probability of an encounter between a predator and prey leading to the prey’s capturea = the efficiency of a predator converting consumed prey into predator offspringm = per capita mortality rate of predatorsisoclines: the population size of one species that causes the population of another species to be stable.For prey, this occurs when P=r/c and for predators when m/ac=V.Cycling:Joint population trajectory: the simultaneous trajectory of predator and prey populations.Joint equilibrium point: the point at which the equilibrium isoclines for predator and prey populations cross. test of model predictions—E. coli and T4 phageThe predator population responded more to an increase in food supply than the prey population.Functional responses: the relationship between the density of prey and an individual predator’s rate of food consumption. Type I functional response: when a predator’s rate of prey consumption increases in a linear fashion with an increase in prey density.As prey density increases, predators consume a constant proportion of prey.Type II functional response: when a predator’s rate of prey consumption begins to slow as prey density increases and then plateaus; often happens because predators must spend more time handling more prey or become satiated.Any increase in prey density is associated with a slowing rate of prey consumption. Type III functional response: when a predator exhibits low, rapid, and slowing prey consumption under low, moderate, and high prey densities, respectively.Low consumption at low prey densities may occur for three reasons: 1. Prey can easily find refuges to hide.2. Predators may have less practice at locating and catching prey but develop a search image at higher prey densities.predator satiation: is an antipredator adaptation in which prey occur at high population densities, reducing the probability of an individual organism being eatenprey switching: Predators may exhibit prey switching by changing their diet preferences to the more abundant prey.search image: a learned mental image that helps a predator locate and capture food.Numerical response: a change in the number of predators through population growth or population movement due to immigration or emigration.Populations of predators usually grow slowly relative to populations of their prey, but the movement of mobile predators can occur rapidly when prey density increases.Population trajectories: Lotka-Volterra predictions/testsFactors that stabilize pred/prey cycles– Predator inefficiency– Density-dependent limitation outside relationship– Alternative food sources– Prey refuge at low density– Reduced time delaysEquilibrium points and alternative stable statesPredator: 0, Prey: 0Predator: 0, Prey: KPredator: K, Prey: 0Predator: r/c, Prey: d/ac--Joint Equilibrium PointA population may have more than one stable equilibrium point– Alone or with low population of other species: K– With strong predator: d/acConsumer-imposed equilibriumResource-imposed equilibriumEvolution of defenses