霊長類行動学11. オス同士の関係パターン

霊長類行動学もくじ

Primate Males

• characteristics of male behavior
• primary interest
  • reproductive success
  • enormous reproductive potential - skew
    • only limited by female resources

• reproductive success
  • benefit of long life +
  • reproductive output. ie effort
  • how much energy you invest
  • more important
• these tow are contingent to reproductive success is relative to other males.
  • (female compete for food for offspring)
  • but male, only thing they care is
• one male's benefit if other male's loss
  • why?
  • sex ratio : 1:1
  • if you mate with more than one, some males loses chance
• male sacrifice long life in order to maximize RS

male strategies is contingent with two things

1. distribution of females in space and time - measure potential of competition.
   • operational sex ratio - refer to old note!
2. distribution and strategy of other males
   • female counter strategies
     • males strategies are not always accepted by females
   • male strategy is divided into two
     1. contest (mostly) - fight against to exclude others
     2. scramble - deferred contest (sperm competition in promiscuity)
        • if dispersed
        • e.g., Gibon

• if females dispersed - males are dispersed, too.
• Polygynous mate guarding
  • range v. rove
    • over density period of time
  • Area x #females x p(female is receptive) x p(another male mate with other female)
    • low: stick to one female (e.g., Gibon)
    • high: male wanders around (e.g., Orangutan)
    • to maximize reproductive success
    • also works for groups, too.

• Gibon are rare in estrous, and female dispersed, so stick with one female.
  • remember: Monogamy is only when males were forced to be from some reasons
  • in Gibon's case, payoff is too high

female group size changes male's mating strategies

• small female group size
  • single resident male
  • other males
  • reason why other males leaves is fighting against the resident male is an unstable strategy (game theory)
    • not enough benefit to risk because there are only few females

if mating is

• seasonal - multi-male influx
  • small group of female
  • within all mate band - peaceful
  • end up with promiscuity mating
• aseasonal
  • seek tenure

霊長類行動学もくじ