living in groups Flashcards
lecture 3
what is a group of insects called
swarms, colonies
what are groups of fish called
shoals, schools
what are groups of birds called
flocks, colonies
what are groups of mammals called
prides, herds, packs
4 anti-predator benefits
dilution effect, vigilance, confusion effects, group defence
dilution
safety in numbers
probability of attack decreases with flock size
avoiding predation
success of an attack decreases with increasing flock size
group size effects on vigilance
vigilance increases with flock size
information centre hypothesis (ICH) - getting food
unsuccessful foragers recognise successful ones, and follow them on their next trip
communal roots may serve to transmit the info about location of food
why is foraging success of animals of different
because some foragers are more successful than others
catching difficult prey
feeding success of predatory fish increases with shoal size
benefit isn’t shared equally - ones at the front get more prey than those at the back
group size effects in African wild dogs
correlation between group size and energy return on hunting
group size influences prey
group size influences interspecific competition
lion coalitions - male competitive ability
improved defence against take over/infanticide
cheetah coalitions - male competitive ability
improved territorial defence - improved RS
costs of group living
inbreeding in stable groups
feeding interference
increase disease risk
increased competition for mates
intra-specific fighting
resource depletion
increased conspicuousness
optimal group size
small groups - fitness may increase with group size since benefits are increasing
large groups - fitness may decrease since costs are increasing -> optimal group size
optimal group size may be unstable
