Biol 301 1nd Edition Lecture 13Outline of Last Lecture I. Exam #2Outline of Current Lecture II. Species InteractionsIII. ResourcesIV. Population CyclesV. ResponsesCurrent LectureInteractions - - Herbivore-Planto Folivore, frugivore, granivoreo Grazers, browsers- Predator-Preyo Insectivore, piscivore, avivoreo CarnivoreResources – • Any substance or factor that is both consumed by an organism and supports increased population growth rates as its availability increases o Consumed, availability decreases o Used for maintenance and growtho Reduced availability reduces population growth- Limiting resource – a resource whose available quantity cannot meet a population’s requirement for itCycles – - Lotka-Volterra Predator/Prey model: a model of predator-prey interactions that incorporates oscillations in predator and prey populations and shows predator numbers lagging behind those of their prey.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Growth of prey populations depends on the growth rate of a prey population and the rate ofindividuals killed by predators - Similarly, growth of predator populations depends on growth rate of predator populations minus the rate of predator death - A prey population is stable when its rate of change is zero. Hence, a prey population is stablewhen the addition of prey is balanced by the consumption of prey. The prey population will increase when the addition of prey exceeds the consumption of prey- A predator population is stable when its rate of change is zero. Hence, a predator populationis stable when the addition of predators is balanced by the mortality of predators. The predator population will increase when the addition of predators exceeds the mortality of predators- Equilibrium (zero growth) isocline: the population size of one species that causes the population of another species to be stable. As the number of predators or prey changes and moves away from the equilibrium isoclines, populations will increase or decrease.- 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.o If either of the populations stray from the equilibrium point, they will oscillate around the point.Responses – - The Lotka-Volterra model does not incorporate time delays, density dependence, or realisticforaging behavior of most predators.- Functional response: the relationship between the density of prey and an individual predator’s rate of food consumption.- Whenever prey density increases and a predator can consume a higher proportion of those prey, the predator can regulate the growth of the prey population.- Type I functional response: when a predator’s rate of prey consumption increases in a linearfashion 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: o 1. Prey can easily find refuges to hide.o 2. Predators may have less practice at locating and catching prey but develop a search image at higher prey densities.- Search image: a learned mental image that helps a predator locate and capture food.o 3. Predators may exhibit prey switching by changing their diet preferences to the more abundant prey.- 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 canoccur rapidly when prey density increases.- Oscillations predicted by Lotka-Volterra- Many populations are more stable—why?o Predator inefficiencyo Density-dependent limitation outside relationshipo Alternative food sourceso Prey refuge at low densityo Reduced time delays- A population may have more than one stable equilibrium pointo Alone or with low population of other species: Ko With strong predator: d/aco Consumer-imposed equilibriumo Resource-imposed equilibriumo Only 1 equilibrium point at a time, hard to change, but environmental variation can induce