Primate Behavioral Ecology Midterm

Primate

Mammal order with traits adapted for arboreal life, sociality, and flexible behavior.

Key Traits and Trends

• Grasping hands/feet (opposable thumbs/big toes)

• Forward-facing eyes → depth perception

• Reduced reliance on smell, enhanced vision

• Large brains, slow life histories (long gestation, parental care)

• Social behavior & learning flexibility

Key Evolutionary Trends

-Arboreal adaptation: flexible limbs & grasping

-Dietary flexibility: generalized dentition 

-Visual Specialization: color vision in diurnal species

-Reduced olfaction compared to other mammals

dentition

the arrangement or condition of the teeth in a particular species or individual

diurnal

during the day or daily

olfaction

the sense of smell

Strepsirrhines (prosimians): types of animals

lemurs, lorises, galagos

Strepsirrhines (prosimians): Traits

rhinarium (wet nose), nocturnal, grooming claw

Haplorrhines (anthropoids): types of animals

monkeys & apes

Haplorrhines (anthropoids):Traits

dry nose, larger brains, diurnal

Tarsiers: types of animals

Haplorrhines but “prosimian-like”

Tarsiers: traits

small, nocturnal, insectivorous

Platyrrhines aka…

New World Monkeys

Platyrrhines (New World monkeys): Traits

flat noses, prehensile tails, South America

Catarrhines aka…

Old World Monkeys and Apes

Catarrhines (Old World monkeys + apes): traits

downward nostrils, Africa/Asia

Cercopithecoids (OW monkeys) vs. Hominoids (apes): Cercopithecoids

tails, quadrupeds, bilophodont molars

Cercopithecoids (OW monkeys) vs. Hominoids (apes): Hominoids

no tail, brachiation, Y-5 molars, larger brains

Quadruped

an animal with four feet

Bilophodont

having teeth with two transverse ridges or crests

brachiation

a form of locomotion in which an animal swings from branch to branch using only its arms.

The 6 Ape Species

1. gibbon (lesser ape)

2. siamang (lesser ape)

3. gorilla

4. chimpanzee

5. bonobo

6. orangutan

The 4 Great Apes

1. orangutans

2. gorillas

3. chimpanzees

4. bonobos

Natural Selection

Differential reproductive success of heritable traits.

Inclusive Fitness & Kin Selection:

• Hamilton’s Rule: r*B > C → altruism (b) benefits relatives, weighted by relatedness ®, exceeds cost ©

• Kin selection: favor relatives → shared genes passed on.

Reciprocal Altruism

Helping non-relatives with expectation of return (e.g., grooming, alliances).

Sexual Selection

• Traits improving mating success (e.g., dominance, ornaments, displays).

• Male competition vs. female choice.

Social Dominance

Hierarchies reduce conflict; affects access to food/mates

Reproductive Success

• Measured by number of surviving offspring

• Tied to dominance, alliances, parental investment

Optimal Foraging Theory

Maximize energy intake per effort/time; Balance energy gain vs. risk vs. travel cost

Adaptationism

Behavioral/physical traits exist due to outcomes of selection; must test, do not assume

Japanese Primatology

Long-term, cultural behavior emphasis; e.g., macaque sweet potato washing.

Long-Running Field Sites: Advantages

multigenerational data, behavioral consistency

Long-Running Field Sites: Challenges

habituation effects, funding, observer bias

The Greeks 

Contributed early ideas of human nature

Al-Jahiz

Early theory of environmental selection (pre-Darwin)

Linnaeus

Binomial nomenclature; human taxonomy classification

Charles Darwin

Natural Selection

Alfred Russel Wallace

co-discovered evolution by natural selection

Gregor Mendel

Heredity laws

J.B.S Haldane

population genetics, kin selection idea

Trimates:

• Jane Goodall

• Dian Fossey

• Biruté Galdikas

Trimates: Jane Goodall

chimpanzees

Trimates: Dian Fossey

gorillas

Trimates: Biruté Galdikas

orangutans

Foraging & Nutrition: Dietary Categories

• Insectivory (protein, high energy)

• Gumnivory (sap, carbs)

• Folivory (leaves, fiber, low energy)

• Frugivory (fruit, sugars)

• Omnivory (mixed diet)

• Gramnivory (grasses/seeds)

Food defenses

tannins, alkaloids, hard shells

Seasonality

affects group movement and competition

Territoriality

• Home range: total area used

• Core area: most used part

• Territory: defended area

• Day range: distance traveled daily

• Territoriality evolves when: resources defendable & competition high.

Benefits of Group Living

Protection from predators, social learning, access to mates

Costs of Group Living

Competition for food/mates, disease, aggression

Socio-Ecological Model (SEM):

• Explains variation in primate social systems.

• Female distribution driven by food → male distribution driven by females.

• Predicts group size, cohesion, and mating patterns.

Dominance Rank

predicts priority access, affects stress/hormones

Philopatry

remaining in natal group (female philopatry = common in matrilineal species; male in some apes)

matrilineal

of or based on kinship with the mother or the female line.

Exam Tips

• Read carefully; underline “always,” “never,” “only”.

• Skip & return if stuck.

• Answer every question.

• For written responses, name specific people, species, and theories.