Predator-prey interactions and anti-predator behavior

11/12 lecture & midterm 3 content

search

find prey

ambush

hide and wait for prey to approach

crypsis

blend in to avoid detection by prey

aggressive mimicry

appear attractive/non-threatening to lure prey

active search

move through environment searching for prey

attack

capture prey

stealth

sneak up & attack prey without being detected

overpowering

openly chase and overcome prey

avoid/deter

prevent attack

predation modes

search & attack

anti predator tactics

avoidance & confrontation

avoid attack

elude detection by predators

deter attack

advertise to or harass predator

Batesian mimicry

mimic the sound of a toxic moth to trick the bat into thinking the mimic is also toxic

survive

get through an attack

escape

evade attacking predator

resist/repel

withstand or ward off attacking predator

the death-dinner principle

performance during each encounter is a matter of life or death for prey, but only a missed meal for the predator

evolutionary arms race

an evolutionary struggle between species that develop adaptations and counter-adaptations against each other, resembling an arms race

the arms race between predator and prey is evident in three areas..

camouflage/crypsis, weapons & armor, sensory adaptations

cryptic coloration

body coloration that matches the color of the environment

cryptic behavior

behavior that allows the animal to blend into the environment

search image

visually distinctive features of an object, like a single prey type

aposematism

warning coloration, that they taste bad

disadvantages of crypsis

• only works in matching environment (unless have active matching capabilities)

• makes it harder for conspecifics to locate each other for mating

• often require animal to hold still or perform specific motions, sacrificing time spent on feeding, mating, and other critical behaviors

disadvantages of aposematism

• some predators likely to evolve tolerance and coloration makes hiding difficult

• producing colors and toxins can be metabolically expensive, takes energy from growth & reproduction

• certain proportions of population will be injured or killed by naive predators before they learn of the danger

weapons and armor

spines, stingers, toxins, etc.

behavioral trade-offs

sacrificing one behavior for another (ex: feeding vs. anti-predator behavior)

vigilance behavior

scanning the environment for predators

predator harassment

rapid movement around a predator that may be coupled with loud vocalization

mobbing behavior

harassment of predator by multiple individuals

move on hypothesis

predator harassment may cause predators to move away from an area

persuit-deterrence hypothesis

advertisement behavior informs a predator that it has lost the element of surprise, so pursuit is not likely to be successful

alarm signal hypothesis

advertisement behavior warns conspecifics of a nearby predator

dilution effect

the probability of dying in a predator attack is reduced by the presence of others

• there is a 1/N probability of dying when a predator makes a single kill from a group of N individuals

• as groups size (N) increases, the probability that any given individual within the group will die (1/N) decreases

group size effect

as a group size increases, each individual can reduce their vigilance behavior because collective vigilance is high

selfish herd hypothesis

individuals can reduce predation risk (and reduce the need for anti-predator behaviors) by moving to the center of a group; this is because a predator is more likely to kill a member on the outside of a social group