The evolution of eusociality: no risk-return tradeoff but the ecology matters

Jeremy Field*, Hiroshi Toyoizumi

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

8 Citations (Scopus)


The origin of eusociality in the Hymenoptera is a question of major interest. Theory has tended to focus on genetic relatedness, but ecology can be just as important a determinant of whether eusociality evolves. Using the model of Fu et al. (2015), we show how ecological assumptions critically affect the conclusions drawn. Fu et al. inferred that eusociality rarely evolves because it faces a fundamental ‘risk-return tradeoff’. The intuitive logic was that worker production represents an opportunity cost because it delays realising a reproductive payoff. However, making empirically justified assumptions that (1) workers take over egg-laying following queen death and (2) productivity increases gradually with each additional worker, we find that the risk-return tradeoff disappears. We then survey Hymenoptera with more specialised morphological castes, and show how the interaction between two common features of eusociality – saturating birth rates and group size-dependent helping decisions – can determine whether eusociality outperforms other strategies.

Original languageEnglish
Pages (from-to)518-526
Number of pages9
JournalEcology Letters
Issue number3
Publication statusPublished - 2020 Mar 1
Externally publishedYes


  • Bees
  • Hamilton's Rule
  • Hymenoptera
  • bet-hedging
  • eusociality
  • inheritance
  • social behaviour
  • social evolution
  • wasps

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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