Animal Behavior: Group living and social behaviour lecture 2

Question 1

What are Primates?

Answer 1

-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

Question 2

What are the costs to group living?

Answer 2

• more easily attract predators
• competition for access to food or mates
• increased food requirements, increased time spent searching for food
• increased disease transmission

Question 3

what are the benefits to group - living

Answer 3

• 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”

Question 4

what is resource defence hypothesis?

Answer 4

-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

Question 5

What is predation defence hypothesis?

Answer 5

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

Question 6

What is philopatry?

Answer 6

when an individual shows the tendency to remain in their natal group

Question 7

what is female philopatry?

Answer 7

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)

Question 8

what is male philopatry?

Answer 8

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

Question 9

what is dispersal

Answer 9

refers to the emigration from a social group ( leaving a group)

Question 10

what is male- biased dispersal?

Answer 10

males typically leave the group
- is most common type in mammals and primates
- is found where females are philopatric

Question 11

what is female - biased dispersal?

Answer 11

females leaving the group
- occurs with male philopatry; less common

Question 12

What are the reasons for dispersal?

Answer 12

• inbreeding avoidance
• better mating opportunities elsewhere
• competition over resources

Question 13

What is solitary/ semi - solitary?

Answer 13

Offspring live w/ mother until old enough to fend themselves
- animals only come together to mate

Question 14

what is pair living?

Answer 14

one male, one female and offspring
- live together in same territory or home range

Question 15

What is is single - male groups?

Answer 15

• used to be called “harems”
• 1 male with 2 or more females
• some “bachelor” groups w/ this type of social system

Question 16

What is multi- male or multi - female groups?

Answer 16

multiple adults of each sex

Question 17

What is fission- fusion type?

Answer 17

Social groups split into smaller feeding parties

Question 18

What is multi male, single female?

Answer 18

1 female with 2 or more males and offspring
- males provide extensive parental care

Question 19

What is monogamy?

Answer 19

1 male mates with 1 female exclusively

Question 20

What is EPCs

Answer 20

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

Question 21

what is Polyandry

Answer 21

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

Question 22

What is polygyny?

Answer 22

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

Question 23

What is polygynandry?

Answer 23

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

Question 24

How is dominance measured?

Answer 24

• outcome of agonistic interactions

Question 25

How is dominance status communicated

Answer 25

• Presentations ( submissive signal)
• displacements( also called supplants
• bared teeth display
• mounting
• open - mouthed stare

Question 26

What are the benefits of dominance?

Answer 26

• confers priority of access to resources ( female - improves body condition)
• for males, leads to higher mating and reproductive success

Question 27

How do individuals attain dominance?

Answer 27

• can climb hierarchy by challenging more dominant animals
• can leave social group and enter another at a higher rank

Question 28

What are the reasons for affiliative behaviors?

Answer 28

Reciprocal altruism: behaviors that are costly to the actor but beneficial to the recipient and reciprocated by the recipient