L10 - Group living Flashcards
(14 cards)
under what conditions do individuals choose to live in a group
the average fitness is higher if living in a group compared to a solitary individual, not equally as useful to everyone but average higher, groups can also be short term and unstable, thus will fall apart as soon as group living not beneficial anymore
what are some costs of group living
increase in diseases, pathogens and parasites, higher rate of conflict, being more obvious and noticeable
what are some benefits to group living
defence against predators and abitoic factors better, foraging may be easier, reproduction more convenient
what are some examples of conflict that may occur in groups and how is it resolved
can occur because of competition of resources, eg in jackfish where position in hunting group will dictate how much prey captured, there might be aggression against an individual which will further increase rate of aggressive encounters towards that individual, it is managed through social behaviours, such as touching, grooming, greeting, seen in mammals but also ravens and decreases reoccurring acts of aggression
what are some ways in which defence may be different in a group compared to when solitary
mobbing calls - adults attack/annoy predator to protect juveniles/eggs (proactive), passive defence through confusion and dilution effect, increased vigilance, where in pigeons time increases but per individual time decreases
how is foraging in groups different that foraging in solitary
groups better at finding food and show local enhancements, such as sharing information about a food source, however in some populations (great tit) food not shared equally, there is a threshold of population size in which grooup foraging more successful than individual (can have too large of a group)
what are the two hypothesis of how intitially breeding colonies might have been formed
habitat copying and mate choice copying
explain what habitat copying is
individuals aggregate and defend nest sites (no other resources present), sites ranked based on breeding success, sites that are highly ranked will have individuals return to them, therefore colony formation is a byporduct of everyone going to the best sites
explain what mate choice copying is
in socially monogamous animals, females have EPC which makes males aggregate, thus colony fomration is a byproduct of forming “hidden lek”, colony forming only beneficial because all males are seen together, but doesnt benefit anyone in terms of territory or resources
what are the 2 ways through which group cohesion is maintained
self-organization and leadership
explain the 3 simple mevhanisms through which animals ensure to stick together in herds etc
repulsion - move away from others (centre)
orientation - align with others (middle)
attraction - move towards others (edge)
depend on where individual is situated within the herd
what is hamiltons geometry for selfish herd
because edge is the easiest target for predators/harsh conditions, individuals should jockey for position in the muddke, which reinforces group cohesion
how is group cohesion maintained through leadership
personal leadership or despotism seen eg in gorillas, where one decides
distributed leadership or democracy, where decision making is shared, signal to move by leader does require voting (gorillas, red deer)
what is the term quorum and how does it relate to group cohesion
the probability of agreeing with another individual’s decision to move and that its predcited by social affiliation, eg more grooming, more likely that 2 individuals will share the same stance, depends on centrality
