Local mate competition with lethal male combat: Effects of competitive asymmetry and information availability on a sex ratio game

Jun Abe, Y. Kamimura, H. Ito, H. Matsuda, M. Shimada

Research output: Contribution to journalArticle

37 Citations (Scopus)


We constructed a sex allocation model for local mate competition considering the asymmetry of competitive abilities among sons. This model assumes two females of a parasitoid wasp oviposit on the same host in sequential order. The evolutionarily stable strategy will be in either Stackelberg or Nash equilibrium, depending on whether the females can recognize their opponent's sex ratio or not, respectively. The Nash equilibrium predicts the second female produce more males than the first. If the second female is able to know and respond to the strategy of the first (a Stackelberg equilibrium), the first will decide an optimal sex ratio assuming that the second reply to it. Under such an assumption, our model predicts that not producing sons is adaptive for the second female when the sons she produces have low competitive ability. Males of parasitoid wasps Melittobia spp. are engaged in lethal male-male combat, indicating large asymmetry in mating success among sons. If females have the ability to recognize their opponent's sex ratio, our model suggests that the severe lethal male-male combat may be one factor explaining their extremely female-biased sex ratio that is unexplainable by pre-existent models.

Original languageEnglish
Pages (from-to)607-613
Number of pages7
JournalJournal of Evolutionary Biology
Issue number4
Publication statusPublished - 2003 Jul 1
Externally publishedYes



  • Lethal male combat
  • Local mate competition
  • Melittobia
  • Nash equilibrium
  • Parasitoid wasp
  • Sex ratio
  • Stackelberg equilibrium

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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