Lecture 7 Week 4 Chap 6. Primate Ecology and Cognition.

Primate are Social Animals facts

Live in groups and or troops

80% of the primate species live in groups

Rarely will you see mammals of mixed-sex groups that are together year-round

Group living is costly

Costs of living in groups

-Group living reduces individual reproductive success due to increased competition for mates, but it also enhances protection against predators and allows for cooperative foraging.

-Numbers attract predators

-Competition for food

-Increased time spent searching for food

-Increased disease transmission

Why do they form groups?

  1. Resource defense hypothesis.

    -Being in a group improves access to for individuals compared to being alone.

    -Larger groups defend resources better.

    -They can out-compete rival groups

    -They can also share information more effectively, enhancing their ability to locate food and evade predators.

  2. Predation defense hypothesis

    • Protection from predators

    • Detection: more eyes to spot predators

    • Deterrence: More individuals to mob predators

    • Dilution: Individuals being targeted by a predator decreases

    • .

Evidence for both hypothesis

Terms for defining social groups

  • Philopatry: the tendency of individuals to remain in or return to their birthplace.

  • Female philopatry: the tendency for female individuals to remain in their natal group

  • Male philopatry: the tendency for male individuals to remain in their natal group,

  • Dispersal - refers to the emigration from a social group (leaving a group)

  • Male-biased dispersal: males typically leave the group (i.e. at sexual maturity)

  • Female-biased dispersal: females typically leave the group

Reasons for dispersal

-To avoid interbreeding

-Better mating opportunities elsewhere

-Competition over resources

Sex-biased dispersal

Male dispersal is most common among mammals and primates and females in this group is more likely to be philopatric (they remain with the group) . (Savannah Baboon, Ring tail Lemur).

Female dispersal occurs when males are philopatric. (Chimps)

Dispersal by both sex (non is philopatric). (Mountain gorillas, red-bellied Lemur)

Primate behavioral ecology

-Selected for and shaped by the ecology of the environment(s)

-Primate behavior is influenced and shaped by the environment in which they evolved.

Each organism fills an ecological niche

-An ecological niche is the role an organism plays in its environment, including where it lives, what it does, and how it adapts to survive.

  • Tropical and Temperate Zones

    Primates are found in forests, woodlands, grasslands and savannas

  • Tropics: almost all primates live in tropics: warm temperatures and humid, only wet and dry seasons

  • Tropical rainforest: Stable temperatures and extremely humid.

  • Tropical dry forest;

  • Woodlands:

  • Savannas;

Primate adaptations and habitat type

• TRF primates – more arboreal, more dietary specialists, some species will have tails used for hanging, sometimes smaller home ranges

•Woodland/savanna – more terrestrial, diet is more generalized and larger home ranges to account for widely dispersed food, smaller tails (not needed for balance)

Primates are intelligent

-Can use tools:

Rocks and branches, they throw them as weapons

To hunt for food (sticks as spears)

-Can learn; active teaching to use tools (only among some apes)

-Have traditions/culture; potato washing, using different fishing techniques

-They plan for the future; Santino the chimp sock-pilled weapons to throw at the spectators the night before.

Why are they intelligent?

-Ecological factors

-Social factors