Sexually dimorphic male horns and their use in agonistic behaviors in the horn-headed cricket Loxoblemmus doenitzi (Orthoptera: Gryllidae)

Hokyung Kim, Yikweon Jang, Jae C. Choe

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Sexual dimorphism, the difference between the sexes in secondary sexual characters, is in general driven by processes of sexual selection. The horn-headed cricket, Loxoblemmus doenitzi, exhibits sexual dimorphism in head shape. Males have flat heads and triangular horns on both sides of their heads, whereas females have rounded heads and no horns. We hypothesized that male horns have evolved due to intra-sexual selection, in which males use these horns as weapons in aggressive interactions. We tested two predictions of this hypothesis by conducting agonistic trials with field-caught males of L. doenitzi: (1) the horns should be used in agonistic interactions between males, and (2) the asymmetry in horn size or horn use may determine contest outcome. Horn length was significantly correlated with thorax length and hind femur length. During agonistic interactions, males aggressively used their horns by beating the opponent's horns with their own or by poking the opponent's body. However, logistic regression analysis revealed that neither horn length nor horn use were significant factors for contest outcome. Instead, body size was significant for determining contest outcome. We discuss possible scenarios for evolution of male horns in L. doenitzi.

Original languageEnglish
Pages (from-to)435-441
Number of pages7
JournalJournal of Ethology
Volume29
Issue number3
DOIs
StatePublished - Sep 2011

Keywords

  • Agonistic behavior
  • Calling song character
  • Loxoblemmus doenitzi
  • Secondary sexual character
  • Sexual dimorphism

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