FÖ4 Evolution of Social Behaviour (ch. 3-4)

Direct cooperation

both individuals benefit here and now

Delayed cooperation

one individual benefits now, the other later

Reciprocal altruism

one individual benefits now, the other later (is paid back)

• Requirements (to avoid cheats):

  • Repeated interaction

  • Recognition of others

  • Remembering each other

Selfishness

Donor benefits, recipient suffers

• Ex. stealing food

• Common

Spite

Donor and recipient suffer

• Rare, few examples

Mutualism

Both donor and recipient benefit

• Split into many different types

• Direct or delayed

• Ex. animals that eat bugs off of other animals

Cooperation

Both mutualism and altruism, benefit to receiver

Altruism

Donor suffers while recipient benefits

• Often evolved due to kin-selection

Communication

The transfer of information

• receivers can obtain useful information by paying attention to signals

• maintenance depends on the information being useful

• the stability of the system requires a mechanism that prevents cheating

Honest

Signal provides true information

• Ex. marking territory, aggressive displays, pursuit-deterrent signals

Dishonest/deceit

Signaller provides false information

Mullerian mimicry

• Signals of two or more toxic prey mimic eachother

• Sharing common predators

• Mutual benefit

• Ex. some butterflies

Aposematism

biological means by which a dangerous, or noxious, organism advertises its dangerous nature to a potential predator

Batesian mimicry

Harmless species (mimics) deter by falsely imitating a toxic/dangerous species (model)

• Similar phenotype

• Only works if the model is present in the area

• Ex. coral snake mimics

Aggressive mimicry

Predators doing camouflage to blend in before striking prey, also any type of luring prey with the body

• Ex. fish that blend in with coral

Interceptive Eavesdropping

A signaler sends a signal to an intended receiver, but the signal is also received by an unintended receiver

Social Eavesdropping

Unintended receivers glean signals by observing the behavior of interactants within a communicative exchange

Sensory exploitation/bias

• Preferences being by-products of how nervous systems process stimuli

• Not necessarily related to the information content of the signals

• Example: Swordtails

  • Females of swordless species prefer a male with a sword put on

Panda principle

Evolution is blind and acts on what already exists, this may lead to strange solutions

• Simulated sex in all female lizard species increases chances of eggs

• Pandas evolving a false thumb

Illegitimate signaller

Signaller (predator) attracts prey by sending a false signal

Illegitimate receiver

Receiver that intercepts a signal not meant for them

Ex. predators that locate prey by hearing their “mate-attracting” calls

Kin selection

Selection for phenotypes that benefit the relatives of that individual, even if it lowers the direct fitness of that individual

Spring-loaded

When a gene/phenotype does not matter until something changes, then it has a very high fitness and “shoots off”

Invasion fitness

a mathematical expression for the long-term exponential growth rate of the mutant subpopulation when it is introduced into the resident population in small numbers