predation and herbivory

predation and herbivory

accidental (or intentional) introduction of a predator or herbivore can have major effects on an ecological community

introduced, exotic, or non-native species

introduced to a region of the world where they have not historically existed

invasive species

introduced species that spread rapidly and negatively affect other species

mesopredators 

relatively small carnviore that consume herbivores

top predators

typically consume both herbivores and predators (mountain lions, wolves, sharks)

what do predators that exihibit active hunting strategies spend most their time on

moving around looking for prey

what do predators that exhibit ambush (sit-and- wait) hunting strategies do

wait for prey to pass by 

hunting can be thought of as a series of events

detecting, pursuing, catching, handling, and consuming prey

antipredator adaptations

traits that increase an organism avoidance or survival following encounters with predators

crypis 

camouflage that either allows an individual to match its environment or breaks up the outline of an inidividual to blend in better with the background 

what was showed by pygmy seashorses

if you introduce a baby seashorse before it has a color that is different from the parent it changes to that color of reef

warning coloration (aposematism)

a strategy where distastefulness (or being “dangerous”) evolves in association with very conspicuous colors and patterns

if predators avoid aposematic species then individuals of palatable species resembling the distastefull species are what 

favored by selection 

bateasian mimcry

when palatable species evolve warning coloration that resembles unpalatable species

mullerian mimcry

when several unpalatable species evolve a similar pattern of warning coloration

what do structural defenses reduce 

a predators ability to capture, attack, or handle prey 

what caused the evolution of plant defenses

selective pressure from herbivores (phenotypically plastic defenses induced by attack or fixed defenses)

what do structural defenses deter

herbivores from consuming leaves, stems, flowers, and fruit

antipredator adaptations can be what

plastic to allow animals to flexibly respond to presence of predators 

behavioral defenses are often costly because of what

result in reduced feeding activity or crowding in locations away from predators (can reduce growth, development, and reproduction)

coevolution

when two or more species affect each other’s evolution

functional response

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

type 1 functional response

when a predator rate of prey consumption increases in a linear fashion with an increase in prey density until satiation occurs

type II functional reponse

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

type III functional response 

when a predator exhibits low, rapid, and slowing prey consumption under low, moderate, and high prey densities, respectively 

search image

a learned mental image that help a predator locate and capture

why does low consumption at low prey densities may occur because of what

predators may have less practice at locating and catching prey but develop a search image at higher prey densities