Social behaviour Flashcards
what is social behaviour
activities among members of the same species
that have fitness consequences on the focal individual and others in the group
3 spatial variation types
clumped
e.g. herds, flocks etc
uniform
e.g. nesting territories
random
e.g. trees
what is a group
a social construct between spatial aggregated participants
which 3 rules govern complex movements?
individuals watch the whole flock and adjust their behaviour to the whole flock
each individual watches 6-7 nearest neighbours + coordinates with them
individuals differ
- there are leaders + followers
what are the 3 patterns that can emerge from simple individual rules?
repulsion
orientation
attraction
opinion polling
individuals make choices and can recruit others to their choice
e.g. nest choosing in bees, ants, gorillas
opinion polling
- nest choosing in ants
scouts can lead a recruit to a new site
-> if a recruit approves it, they can lead a new recruit
at a critical point
- enough recruits are at site to switch from leading behaviour to transport behaviour
(= rates of movement increase + nests are transported + established)
benefits to individuals in the group
- antipredator
- foraging
dilution
confusion
defence
vigilance
better finding
better capturing
diluting the predation probability
via masting/swamping
or selfish herds
the more in your group, the less likely your individual predation
(if attack rate is constant)
masting
when you have an overproduction of progeny in a v limited amount of time
- predators can’t keep up
- > mass increase in prey
selfish herds
you need to be further away from the predator than your neighbour
predation isn’t easily distributed across groups
-> probably attack the closest individual
e.g. seals attack crowd of penguins
confusing predators
as group increases in size
- > predator gets more confused, distracted + can’t focus on an individual
- > successful attacks decrease
defending against predators
by deterring attack e.g. shore birds mobbing gulls to increase their reproductive success
or using formations
vigilance
some birds have their heads up and watch
-> so others can do other things e.g. eat
individuals in group must monitor the alert behaviour of others in the group
- so can know if predators are detected
better finding food
- hypothesis
Information Transfer Hypothesis
- as food quality + quantity increases
they make more noise
SO a group increases the efficiency of finding food via a network
better capturing
hunting in groups means you can catch prey much bigger than you
costs to individuals in a group
- foraging
- risks
-risk of losing
-prey
sharing
- cost of defence
- cost of vigilance
- parasitism
parasitism
the larger the colony, the more parasites they have + lower individual body mass
sharing
the bigger the group size, the lower the relative food intake rate
optimal group size
can be unstable when individual foragers continue to join a group
- beyond optimum group size = fitness falls
- eventually reaching similar levels as in small foraging groups
-> social foraging provides little evolutionary advantage
3 types of social behaviour studying
brain sciences + sociogenomics
sociobiology
sociophylogeography
what is…
sociogenomics?
sociobiology?
sociophylogeography?
what an individual does is influenced by its brain, physiology and genes
investigating individuals within the population
selection produces differences between populations + species
define altruism
individuals give up resources to benefit their neighbours at a cost to themselves
2 ways of modelling social interactions
what is mathematically important about these models?
inclusive fitness approach
multilevel selection approach
they’re mathematically equivalent
inclusive fitness approach
focuses on how an actor affects the fitness of others
- direct + indirect relatedness measures the value of the recipient in transmitting copies of the actor’s own genes
- > leads to a gene-centred view of evolutionary change
multilevel selection approach
focuses on social evolution in terms of selection within group and between groups
overall population will be removed if its below a level of fitness
Hamilton’s rule
a gene invades if rB > C
what is a greenbeard?
a gene in 1 individual generates a phenotype
that causes the actor to:
help those showing the same phenotype or harm those that don’t
-> drive that gene to fixation
greenbeard:
facultative helping
obligate helping
only help other greenbeards
greenbeards help everyone in population BUT only greenbeards benefit
greenbeards:
facultative harming
obligate harming
only harm non-greenbeards
harm everyone
BUT greenbeards with the same gene can protect themselves from harm
multilevel selection
- explain
cooperators have a within-group disadvantage against cheats
-> leads to -ve within-group selection component
BUT groups with more cooperators are more productive
-> leads to +ve between-group selection component
