Living in groups Flashcards
why study groups
-important for understanding behaviour
-group life varies (within and between species)
-group formation varies (different times of year, age, sex classes
-most domesticated species are social species, accustomed to living in groups all or part of their lives
-group dynamics
study individual differences and social roles
-key to understanding behaviour and managment
how to study groups
-studying in in confinement does not help understand social behaviour
-studies done on semi-wild or feral groups in more natural settings
examples of places with natural group studies
-Edinburgh park
-feral horses on sable island
edinburgh pig park
-semi natural environment
-domestic pigs
-natural social behaviour
-nesting for sows
-early excursion from nest
-young boar investigating sow
-social learning and foraging
-playing as a group
-pre-weaning socilization
feral horse research
-Dr philip mcloughlin, biology, u of s
-sabel island horses
-herd of ~500, nova Scotia
-herd increasing (inc in seal population?)
-ecology and evolution
-population
-social relationship
different characteristics seen with domestication
-smaller brain
-less active
-reduced alarm response
-more socially tolerent
simular characteristics with domestication and wild counterpart
-same basic social characteristics
-threshold or frequency of behaviours may change
evolutionary theory
-gives theoretical framework
-predict/understand social organisms
-suggest ways to improve management
natural selection and behaviour
-evolution of adaptive behaviour is no different then evolution of morphological/physiological traits
-for behaviour to evolve:
-there must be behavioural variation within the population
-the differences must be heritable (some of the variation must be genetic in origin)
-some behavioural variations will confer greater reproductive success
how are behavioural patterns selected
so that they will increase an animals chance of survival and reproduction ‘fitness’
human selection of sheep breeds
maternal behaviour in sheep has been modified
why does social groups seem counteractive to animals
groups are facilitated by cooperation but evolutionary theory is usually described in terms of competition among individuals
“survival of the fittest”
social interactions: example of cooperation/mutualism
pack hunting (++)
social interactions: example of selfish
lions killing of offspring (-+)
social interactions: example of altruism
alarm calls (+-)
social interactions: example of spite
tail biting? (–)
theories explaining groups and cooperation
-kin selection (inclusive fitness theory)
-reciprocal altruism (generosity.. you scratch my back..)
-multi-level (group) selection (some selection occurs at group level, there is strength in diversity)
kin selection
-individuals reproduce directly or indirectly by aiding relatives
-group living is facilitated by cooperation between individuals
-individuals can increase their genetic contribution by assisting with the success of relatives (who they share genes with)
-part of inclusive fitness theory
inclusive fitness
if aminal ‘i’ cant procreate then other places on the family tree chave very simular genetic make up so thats the next best way for i to have its genes passed on
halmiltons rule-relatedness
-hamilton took the degree of relatedness into account when addressing altruistic social encounters
-c<rxb
-c=cost
-b=benifit
=r=degree of relatedness
-if the recipient and actor are highly related, how is cost affected
-higher the r the more likely animals will help
can animals recognize close relatives
-identify kin using oral secretions ‘kissing’ can recognize kin even if reared separately (ground squirrels)
-animals such as pigs cant recognize kin if they have been reared seperate
why would non-relatives cooperate (assume cost to actor, no pay off)
-reciprocal altruism: alternating benefits, long-term relationship, i help you and expect a return later (vampire bats)
-multi-level selection: groups that cooperate outcompete those that do not. stable society-cooperation has longterm benifits
examples of cost and benefits of social groups
benefits:
-thermal
-foraging
-predation
costs:
-contamination
-competition
-conspicuous
how do most mammals live socially
they form social groups
why do groups form
to minimize costs and maximize benifits
how are costs minimized when social groups are formed
-limiting group size: according to resources and environment
-social hierarchy: individuals know their place, dominants have priority access to resources. ritualised threats, posturing; reduced aggression
-social rules to reduce competition: dom animals feed first, alliances; preferred partners, allogrooming
foraging advantages in groups
-detecting food (bee waggle)
-acquiring food (wolves, social predators)
-defending food (hyena- food patches, forage kill)
avoiding predation advantages in groups
-detection (can spend less time worrying and more time eating due to shared responsibility)
-dilution (synchronized calving, predators are satiated. also causes a confused effect reducing predator success)
-defence (cattle and flies- rosette formation, horses and flies-tail to tail)
costs of groups
-conspicuous: groups are more easily detected, predators can be attracted by communication
-competition: causes prioritized access to food (hierarchies), acute stress when forming a group, chronic stress from subordination (inability to mate)
-contamination: increased parasites and disease transmission
minimizing costs of living in a groups
-limiting group access: according to resources and environment
-social hierarchy: they know their place, dom have priority access to resources
-social rules reduce competition: dom feed first, ritualised threats (posturing) reduces aggression, alliances preferred partners for affiliation, allogrooming
-when groups form- benefits outweigh the costs
