Group living and dispersal patterns Flashcards
Give an example of two other social mammals which aren’t primates and the advantages of group living
Lions
- females have complex relationships
- no dominance hierarchy
- strong between group competition
- cooperative in hunting, raising young and defence against male infanticide.
African elephants
- complex social structure
- older matriarchs have more finely-honed skills than younger ones. They lead groups with higher reproductive success.
Large matriachal have the most ecological knowledge. However these are normally targeted by poachers. When an old female is lost is has been shown that the reproductive success decreases because they don’t have the knowledge to good resources.
The older the female the better the ability of recognising calls of the clan. If you can recognise a clan member, you don’t waste time in delaying important activities or you can get into a defensive posture.
Why is it argued that sociality is more of a key adaption for primates than for other species
The combination of;
- differentiated within-group relationships
- marked social boundaries
- kin-based social relationships
- use of allies and coalitions in some species
are all unique aspects of primate sociality.
What are the two main costs to group living?
- More competition for food, members of same group are always nearby. (If resources are limited it would make sense to be solitary to have more access to food.
Reproductive success is highly based on access to high quality food so benefits must heavily outweigh costs.)
2.More vulnerable to disease (this has had devastating effects on human population)
What are the two main hypotheses explaining the benefits to group living?
1) Resource defence hypothesis
- improves access to resources by defending food and finding food
- there is a large vs. small group advantage (as group size increases Capuchins win inter-group encounters. Large group size has a benefit as they can out compete the smaller groups for resources. But benefits will eventually plateau due to the carrying capacity of your environment.)
2) Predation defence hypothesis
- being in a group offers better protection from predators.
- collective detection; more eyes and ears to detect predators
- dilution effects; each individual has less of a chance of being caught.
- deterrance; large group may deter a predator by confusing it with high numbers. Probability of being taken by a predator decreases because of the shear number of individuals in a group.
- Increased feeding rates due to decreased vigilance for predators
E.g Leopards won’t go for baboons because of large numbers.
What is meant by “polyspecific associations”?
Different species that regularly travel, sleep and eat together but are made up of different species.
Polyspecific association of guenins and magabeys video - All species recognise each others warning call to the predator so benefits all. The monkeys aren’t fleeing because leopards are ambush predators so once spotted it normally gives up.
Polyspecific association works because of niche partitioning so there is no competition of food or space. Associations between arboreal and terrestrial species for example. No cost of group living but benefit form predation protection.
What are other benefits of group living in terms of reproduction?
- Mates are readily available and are easier to monitor reproductive state. For example the swelling of females bums. The male can monitor when this happens the male can work out when the best time is to try and mate with the female.
- females and offspring may benefit from protection from male con-specifics leading to infanticide protection.
How can you define sociality?
Identify social unit - who actually live cohesively in a group and aren’t individuals crossing paths.
a social group is a maintained sociality with regular behavioural interactions.
What behaviours show strong relationships between primates?
- Affiliation (affiliation behaviours- friendly behaviours. Things that strengthen social bonds.);
- grooming,
- huddling,
- Proximity maintenance (e.g howlers don’t huddle together like lemurs for example. In howlers it is more social to sit at an arms length where as in other species it could be sitting close and grooming that is affiliate behaviour.
- Agnostic support; more negative aggressive behaviour. E.g coalition formation in chimps when they silently patrol the boundaries of their territory.
- Minimal aggression; tolerance of proximity when feeding
What are the different types of dispersal, bonds and social structure for primates.
-Dispersal;
male - biased - males leave at sexual maturity.
opposite in female - biased
bisexual is when both sexes leave at maturity. To avoid interbreeding.
-Bonding;
Female bonded is when females tend to be related and stay together.
Male-bonded is when the males are related or nobody is.
-Social structure; Matrillineal or Patrilineal
What is meant by the suffixes; gamy, gyny and andry
gamy = multiple individuals
gyny = multiple males
andry = multiple females
Describe male-biased dispersal and give examples of species that this is seen in.
- Males leave natal group at maturity.
- Females are resident in the natal group.
- Females tend to be resident because the males typically mature later. This is most commonly seen in the old world monkeys
E.g
Cercopithecines
- Macaques
- Baboons
- Mangabeys
Describe female-biased dispersal and give examples of species that this is seen in.
- Females leave natal group at maturity
- Males are resident in the natal group.
- Characteristic in these groups is a fission-fusion relationship. Way around the costs of group living.
E.g
-chimpanzees
- red colobus monkeu
- spider monkeys
Describe bisexual dispersal and give examples of species that this is seen in.
- Both sexes leave natal group
- in bisexual dispersal the groups tend to feed on grass and leaves which is very easy to access. So no point in building alliances to defend resources because you need the energy to digest.
No point in forming bonds in group so both sexes leave at maturity.
E.g
-Gorrilas
-Howler monkeys
How does dispersal effect relatedness and relationships?
- dispersal influence which sex has relatives in the group. Generally kin are closer than non-kin and make better allies than non-kin.
- Ultimately, influences which relationships are more predominant/important.
Describe relationships in groups that have male-biased dispersal
Because females are resident the group is Matrilocal.
Females form matrilines so the group is female-bonded. (Cercopithecines)
Female-female bonds are more affiliative than female-male bonds
Matrilochal stays in the local area of its kin
Because females stay in the same area, the females hold all the ecological knowledge down the matriachal line.
