Lavc f10 lecture 10   primate ecology
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Lavc f10 lecture 10 primate ecology



Anthro 101:Human Biological Evolution lecture on Primate Ecology. Rebecca Frank, LAVC F2010

Anthro 101:Human Biological Evolution lecture on Primate Ecology. Rebecca Frank, LAVC F2010



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  • Crowned hawk eagle - 80% diet monkey

Lavc f10 lecture 10   primate ecology Lavc f10 lecture 10 primate ecology Presentation Transcript

  • Anthro 101: Human Biological Evolution Lecture 10: Primate Ecology Office Drop-in Hours AHS 308 Tutoring Lab Hours AHS 232 T 5:30 - 6:30 M & T 1 - 4 Th 11:15 - 12:15, 1:15 - 3:15 Student ID required F 12 - 1:30 by appointment
  • Attendance survey
    • List three primate characteristics that differentiate primates from other mammals.
    • Write your name on the other side of the card.
  • Zoo Project - any questions?
    • Friday Oct. 15th & Saturday Oct. 16th @ 9:45
    • Due Oct. 21st - 3rd Exam Oct. 21st
    • Exam 2 Extra Credit - fix your mistakes and show me or Kirsten - Due Oct. 21st
    • Optional Fieldtrip - any interest?
    • Natural History Museum - Age of Mammals
    • Sun. Nov. 7th or Sat. Nov. 20th or Sun. Nov. 21st
    • $6.50 admission, free parking, near USC
  • Why do primates live in groups?
    • Advantages of group life
    • Costs of group life
    • Why do primates live in so many kinds of groups?
      • Balancing costs & benefits
      • Socioecology
  • Behavioral Ecology
    • The study of the evolution of behavior
    • emphasizing the role of ecological factors as agents of natural selection
      • Resources (diet), predators, climate, “conspecifics,” etc.
      • How do these factors affect behavior?
      • In primates, focus especially on the influence of these on social organization
    • Socioecology : the study of how social structure and organization are influenced by organisms' environment
  • 1. Why do primates live in groups?
    • Most mammals are solitary
    • Many prosimians solitary
    • Why are diurnal primates social?
  • Major benefits of group life
    • Protection versus predators
    • Better access to resources
    • Access to potential mates
  • Large cats prey on primates lion leopard jaguar cheetah tiger
  • Large primates can defend themselves against big cats, but many small ones can’t
  • Raptors prey on primates Martial eagle Harpy eagle Hawk eagle
  • Crocodiles can take primates
  • A variety of snakes prey on primates python
  • Primates prey on other primates Chimps hunt red colobus monkeys Baboons prey on vervets
  • Humans and domestic dogs kill primates Hunter with gorilla head Dog with langur infant
  • Predation is rarely observed, but can sometimes be inferred leopard paw print drag marks baboon jaw & hair
  • Indirect evidence of predation
    • Wound observed
    • Healthy animals disappear overnight
    Juvenile, scalp wound Oryx, back wound
  • For diurnal primates, sociality is an effective anti-predator strategy
    • Detection
    • Dilution
    • Defense
  • Detection : In larger groups, there are more eyes to watch out for predators
  • Dilution : In groups, any particular individual less likely to be caught by predator
    • Imagine chance of being caught = 1/ n , where n = group size
    risk = 1/2 risk = 1/12                            
  • Defense : Many strategies for diurnal primates
    • Sleep in trees, cliffs
    • Defensive weaponry
    • Large body size
    • Vigilance
    • Alarm calls
    • Mobbing
    • Interspecific associations
  • Two or more species may associate to reduce predator risk: Interspecific Associations - 3D’s Ground predators Eagles Diana monkey Red colobus
  • Nocturnal primates use different strategies
    • Hide during day
    • Park infants while feeding
    • Solitary
    • Quiet
    • Cryptic
  • Sociality also has costs
    • Competition
    • Contagion
    • Cuckoldry
    • Inbreeding
    • Cannibalism
    • Infanticide
  • 2. Natural selection shapes social organization to balance the costs & benefits of group living
    • Socioecology = study of how ecological forces shape the size and structure of social groups
  • Solitary (but differentiated social relationships)
    • each individual lives alone, occasionally meet up for mating
    • may chose to neighbour with kin, meet more often
    Orangutan Loris
  • Monogamous (territorial pairs + offspring) Titi monkeys Gibbons
  • One-male, Multi-female groups (polygyny) Mountain gorillas Black and white colobus
  • One-female, two-male groups (Polyandry) Pygmy marmoset marmoset Callitrichids
  • Multi-male, multi-female groups Ring-tailed lemurs Savanna baboons
  • Communities (fission-fusion social organization) Spider monkeys Chimpanzees
  • Socioecology : Competition for food is particularly important for females
    • Nutrition affects:
      • Ability to conceive
      • Viability of pregnancy
      • Lactation
    • Male reproduction is more influenced by access to females than by nutrition
  • Food, competition, and social behavior are thought to be linked Dominance Relationships Competitive Regime Distribution of food Value of Alliances Female Relationships Dispersal Patterns
  • The distribution of food affects they type of competition
    • Clumped, valuable patches
    • Dispersed, low value patches
  • The distribution of food affects the nature of competition
    • Dispersed --> scramble competition
      • Food is distributed evenly
      • Food items not worth fighting over
      • Scramble to get enough food
      • no direct competition
    • Clumped --> contest competition
      • Resources are scarce & valuable
      • Resources are worth fighting over
      • Contest access to particular resources
  • Contest competition can produce dominance relationships
    • A & B want same piece of food  FIGHT
    • Bigger, stronger, more experienced one will win
    • When one consistently defeats other = dominance relationship
    • If A always beats B & C
    • And B always beats C
    • = dominance hierarchy
  • Food, competition, and social behavior are thought to be linked Dominance Hierarchy Contest Competition Distribution of food Value of Alliances Female Relationships Dispersal Patterns
  • If dominance rank affects access to resources,
    • Females will strive for high rank
    • Females may benefit from help in their fights
      • Alliances useful
  • If females come to rely on alliances…
    • Will develop relationships with allies
      •  associate with certain females
      •  groom certain females
    • May prefer kin as allies
      • Kin share genes = kin selection
      • Inclusive fitness
    • Will remain with allies/kin
      • Females will be philopatric
      • Males will disperse to prevent inbreeding
  • Alliances can also affect structure of dominance relationships
    • A beats B
    • A helps A’ beat B
    • A’ can beat B
    • A and A’ will outrank B
    • Dominance hierarchy will have female relatives next to each other in rank
    Monkey B Monkey A Monkey A’
  • Food, competition, and social behavior are thought to be linked Dominance Hierarchy Contest Competition Distribution of food Alliances Valuable Close Bonds Female Philopatry Eg: baboons & capuchins
  • If dominance does not affect access to resources, then… Unstable hierarchy Scramble Distribution of food Eg: gorillas & langur monkeys Weak bonds Male/female dispersal No alliances
  • What about males?
    • There are differences between sexes in what matters most for fitness:
      • Female fitness depends on access to resources
      • Male fitness depends on access to females
    • Social organization depends on:
      • Distribution of resources (for females)
      • Distribution of females (for males)
    •  Social organization is driven by sex differences. Why?
  • What about males?
    • Male fitness depends mainly on access to females
    • Males don’t benefit much from alliances - can’t share mating opportunities very well
    • So, males go where females are