Unit 2: Predation Terms

Predation

A plus/minus interaction; consumption of one organism by another where the prey is alive when first attacked 

Predation Def 2

An interaction in which an animals (or animals) kills and more or less entirely consumes another animal (doesn’t include plants)

Prey/Predator Graph

Expectation is an oscillating movement up and down, one goes up, the other goes down and visa versa (parasitoids)

Numerical Response of Predators

Increases in predator population occur through increased reproduction; lot’s of food = lot’s of reproduction (coyotes/rabbits)

Aggregative Response of Predators

Increases in predator population occur on a shorter time scale at a local level; predator’s go where there is lots of prey (red shank bird and shrimp)

Functional Response of Predators 

Relationship between a predator’s feeding rate and prey density; a predator will take/affect more prey as density increases 

Herbivory

Falls under the predator/prey relationship (cactus fly example)

Why do owls not exhibit the traditional prey/predator chart?

They have multiple sources of food.

What is an example of a traditional prey/predator relationship? 

Lynx and snowshoe hare. 

Functional Response 2:

Most typical, # of prey taken/predator rises at a decreasing rate toward a maximum value; handling time exerts its effects gradually.

Functional Response 1:

Much less common, # of prey/predator increases linearly, not gradually, to a maximum as prey density increases; handling time exerts its effects suddenly. 

Functional Response 3:

of prey taken/predator is low at first, then increases in a sigmoidal fashion and plateaus where the attack rate remains constant; type 3 can potentially control prey populations 

Optimal Foraging Theory

Predicts an animal minimizes the cost:benefit ratio; cost/benefit = handling time or energy expended/energy consumed

Optimal Foraging Theory Example

Bass eat crayfish between 15-20 cm; bass always ate small crayfish, would begin to reject as crayfish got larger

Fish and Birds Video 

Large fish ate birds in the water; proves fish brain can plot; prey are not completely defenseless. 

Batesian Mimicry

One species mimics another; one is harmful, the other is not.

Mullerian Mimicry

Both species are harmful; often closely related.

Monarch and Viceroy Butterflies 

Mullerian mimicry; both are toxic.

Caterpillar turns into Snake 

Batsian Mimicry.