Polygyny and Mating Systems

Polygyny

  • Most common mating system in nature.
  • In most species, female resource needs and reproductive behaviors determine which competitive and display maneuvers provide payoffs for males.
  • Male mating tactics are an evolved response to female reproductive needs and ecological factors determining the spatial distribution of receptive females.

Why are males polygynous?

  • Female defense polygyny hypothesis: When resources are evenly distributed, but females form groups for resource access or predation risk dilution, males guard these female groups.
  • Resource defense polygyny hypothesis: When resources are clumped, attract multiple females, and are easily defensible, males guard the resources (and by extension, the females) by setting up a territory.
    • Example: African Cichlid fish, Lamprologus callipterus.

Lek Polygyny Hypothesis

  • When resources are distributed heterogeneously and females are widespread and do not form groups, males will wait for females to come to them at specific locations called leks.
  • Huge inequalities in male mating success (high reproductive skew) are standard features of lekking species.

Why do males form leks?

  • Hotspot hypothesis: Males cluster in "hotspots" where routes frequently traveled by receptive females intersect.
  • Hotshot hypothesis: Subordinate males cluster around highly attractive males (“hotshots”) to interact with females drawn to these hotshots.
  • Female preference hypothesis: Males cluster because females prefer sites with large groups of males, where they can quickly or safely compare the quality of many potential mates.

Testing Lekking Hypotheses: Great Snipe

  • Removal of central dominant males caused neighboring subordinates to leave their territories.
  • Removal of a subordinate while the alpha snipe was in place resulted in his quick replacement on the vacant territory by another subordinate.
  • Observed results support the hotshot hypothesis, suggesting subordinate males gather around dominant males to capitalize on mating opportunities.

Scramble Competition Polygyny Hypothesis

  • When resources are distributed heterogeneously, and females are widespread and do not form groups, males will seek out females.
  • When costs of establishing territories (with or without resources) exceed the benefits, males may simply try to find scarce receptive females before other males do.

Explosive Breeding Assemblage

  • Occurs in species with a highly compressed breeding season in which females may be receptive only during a short window of time.
  • Scramble competition polygyny can be influenced by the distribution of females or the length of the breeding period.