Animal Behavior: Group living and social behaviour lecture 2 Flashcards
What are Primates?
-Primates are uniquely social compared to other mammals
- Involves “ social attraction”
- seek proximity to one another independently of environmental stimuli
- Primates want to be together when not particular function
- their social organization is more complex than other animals
- argued that sociality is thought to be at the very core of primate existence- it is a primate’s principal evolutionary strategy, and what makes them different from all other species
- differentiated withing group relationships
- marked social boundaries
- occurence of kin - biased social relationships
- influence of allies in some species
- combination of each of these features in unique in each primate species
- Primates form groups because mixed - sex groups that are together year- round are rare amongst mammals
- group living is costly
- factors associate with group- living reduce individual reproductive success
What are the costs to group living?
- more easily attract predators
- competition for access to food or mates
- increased food requirements, increased time spent searching for food
- increased disease transmission
what are the benefits to group - living
- resource defence hypothesis
- predation hypothesis
- can out compete other groups in inter- troop competition
- more individuals means more knowledge of resources
- detection: more eyes to see predators
- more individuals to band together to mob a predator
- less likely to be eaten by a predator via the “ dilution effect”
what is resource defence hypothesis?
-Being in a group improves access to resources for individuals compared to being alone
- being in a group improves the ability of females to find and defend resources - they couldn’t do this as well if they were alone with infants
What is predation defence hypothesis?
3Ds
- detection: more eyes to see predators
- detterence more individuals to mob a predator
- dilution: less likely to be eaten by a predator via the “ dilution effect
What is philopatry?
when an individual shows the tendency to remain in their natal group
what is female philopatry?
when females in a species show the tendency to remain in their birth group for their lifetimes
- females are matrilocal ( they live in the same group as their maternal kin)
- matrilines form( females are related to one another through maternal descent)
what is male philopatry?
when males in a species stay in their birth group
- males are patrilocal: they live in the same group as their paternal kin
- male patrilines form: males are related to one another through paternal descent
what is dispersal
refers to the emigration from a social group ( leaving a group)
what is male- biased dispersal?
males typically leave the group
- is most common type in mammals and primates
- is found where females are philopatric
what is female - biased dispersal?
females leaving the group
- occurs with male philopatry; less common
What are the reasons for dispersal?
- inbreeding avoidance
- better mating opportunities elsewhere
- competition over resources
What is solitary/ semi - solitary?
Offspring live w/ mother until old enough to fend themselves
- animals only come together to mate
what is pair living?
one male, one female and offspring
- live together in same territory or home range
What is is single - male groups?
- used to be called “harems”
- 1 male with 2 or more females
- some “bachelor” groups w/ this type of social system
What is multi- male or multi - female groups?
multiple adults of each sex
What is fission- fusion type?
Social groups split into smaller feeding parties
What is multi male, single female?
1 female with 2 or more males and offspring
- males provide extensive parental care
What is monogamy?
1 male mates with 1 female exclusively
What is EPCs
copulations outside a mated pair
- recent research has shown than 12% of gibbon copulations are EPC
- paternity tests in gibbons have shown many infants are produced by EPCs
- EPCs due to both males sneaking copulations with neighbouring females, and females sneaking copulations with neighbouring males
what is Polyandry
1 female mates with multiple males, but each male mates only with that female
- only one reproductively active female in group of many females
- dominants do this by using pheromones to suppress the hormonal system of the subordinate females so they do not ovulate
- lower ranking females do not ovulate until they leave the group or the breeding female dies
- males would provide care for the infants of female because they may have sired them
What is polygyny?
1 male mates with multiple females but each female mates only with that male
- The male would actively try to prevent other males from trying to takeover group and gain sexual access to females
- usually associated with intense sexual dimorphism in body and canine size
- male - male competition
- can take toll on even the strongest and healthiest males
- when sexual access to females is taken over by another male, if male is not killed, they will have to live alone or join an all - male group
What is polygynandry?
both males and females mate with multiple members of the opposite sex
- most dominant male may try to monopolize matings by mate - guarding
- dominant male can only mate- guard one female at a time, so if females have synchronous estrus periods, he cannot monopolize both
- females secure best possible genes for offspring by mating with many males
How is dominance measured?
- outcome of agonistic interactions
How is dominance status communicated
- Presentations ( submissive signal)
- displacements( also called supplants
- bared teeth display
- mounting
- open - mouthed stare
What are the benefits of dominance?
- confers priority of access to resources ( female - improves body condition)
- for males, leads to higher mating and reproductive success
How do individuals attain dominance?
- can climb hierarchy by challenging more dominant animals
- can leave social group and enter another at a higher rank
What are the reasons for affiliative behaviors?
Reciprocal altruism: behaviors that are costly to the actor but beneficial to the recipient and reciprocated by the recipient
