Haplodiploidy, Sex-Ratio Adjustment, and Eusociality

Andy Gardner*, Laura Ross

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)
1 Downloads (Pure)


Hamilton's "haplodiploidy hypothesis" holds that inflated sororal relatedness has promoted altruistic sib rearing in haplodiploids, potentially explaining their apparent predisposition to eusociality. Here, we suggest that haplodiploidy may instead promote eusociality simply by facilitating sex-ratio adjustment. Specifically, haplodiploidy may enable sex-ratio bias toward the more helpful sex, owing to "local resource enhancement," and such sex-ratio bias may promote the evolution of helping by individuals of that sex, owing to the "rarer-sex effect." This could explain why haplodiploidy appears to have been important for eusociality in taxa with only female helpers, such as ants, wasps, and bees, but not in taxa with both male and female helpers, such as termites.

Original languageEnglish
Pages (from-to)E60-E67
Number of pages8
JournalAmerican Naturalist
Issue number3
Early online date28 Jan 2013
Publication statusPublished - Mar 2013


  • Inclusive fitness
  • Kin selection
  • Local resource enhancement
  • Rarer-sex effect
  • Sex allocation
  • Social insects
  • Evolutionary stability
  • Termites
  • Model
  • Cockroaches
  • Behaviour
  • Monogamy
  • Helpers
  • Shrimps


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