bio anthro lecture Group-Living 2.28.2024 (primate sociobiology)

Ecological/Competitive Release

niche expansion following the removal of a constraining variable

Community Ecology

study of interactions among species in communities on many spacial and temporal scales

communities

assemblages of interacting populations of the species living within a particular habitat

disease ecology

study of the interaction of the behavior and ecology of hosts with the biology of pathogens (microbes)

• looks at factors influencing transmission of infectious disease

• triangle between environment, host, and parasite

2 main theoretical frameworks for understanding primate behavior

sociobiology

socioecology

sociobiology

examines behavior in an evolutionary context

social evolution

socioecology

examines how ecology influences behavior

2 strategies to reduce risk of predation

crypsis

group living

crypsis

camouflage - often associated with primates who are nocturnal, solitary, or live in small groups

group living

has evolved as a way to reduce risk of predation

3 reasons group living reduces risk of predation

3 Ds

1. Detection

2. Deterrence

3. Dilution

detection

more eyes and ears to detect predators

deterrence

can mob the predator

dilution

lower probability that you will be the one eaten

relationships between group size and predation risk/resource competition

↑ number of predators → ↑ number of individuals

↑ group size → ↑ resource competition

↑ group size → ↓ predation risk

(sweet spot where resource competition and predation risk overlap → indicate perfect group size)

key concept in socioecology

variation in group size is explained by variation in resource competition and predation risk

types of competition

varies by the distribution of resource

contest

scramble

contest competition

when food is found in patches, monopolizing patches can be beneficial + some group members will get more than others

costs of group living not equally distributed → hierarchies arise

scramble competition

when food is more evenly distributed → no benefit to monopolization + no reason to fight

costs of group living distributed equally as group size increases

5 Costs of Group-Life

1. Direct (face-to-face) competition

2. Spend more time searching for food

3. Cover more distance

4. Coordinate Activities

5. Disease Transmission

gregarious animals have evolved ways to deal with living in close proximity