Chapter 13-Predator and Herbivory

LT1: Predators and Herbivores can limit the abundance of populations.

Introduced species- a species that is introduced to a region of the world where it has not historically existed

Biological control- introductions of one species to help control the abundance of another species.

Mesopredators- relatively small carnivores that consume herbivores

Top predators- predators that typically consume both herbivores and mesopredators

Example: Beetle Herbivory (the beetle population initially increased, and the plant began a rapid decline. Once the plant population declined, the beetle population also declined.

LT2: Populations of predators and prey fluctuate in regular cycles

Lotka Volterra Model- A model of predator-prey interactions

• incorporates oscillations in the abundance of predator and prey populations

• shows predator numbers lagging those of their prey

Equilibrium isocline- the population size of one species that causes the population of another species to be stable (also known as zero growth isocline)

Joint population trajectory- the simultaneous trajectory of predator and prey populations

Joint equilibrium point- the point at which the equilibrium isoclines for predators and prey populations cross

LT3: Predators and herbivores respond to food availability with functional and numerical responses

Functional Response- the relationship between the density of prey and an individual predator’s rate of food consumption

Type 1- a functional response where a predator’s prey consumption rate increases linearly with rising prey density until it reaches satiation

Type 2- A functional response where a predators rate of prey consumption begins to slow down as prey density increases then plateaus when satiation occurs.

Type 3- A functional response where prey consumption is low at low densities, rapid at moderate densities, and slows at high densities.

Search Image= a learned mental image that helps the 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

LT4: Predators and herbivory favor the evolution of defenses.

Crypsis Prey= camouflage that allows them to bend in better with their environment

Batesian Mimicry= palatable species resemble unpalatable species

Coevolution= when two or more species affect each other’s evolution