Random or handedness? Use of laterally paired penises in Nala earwigs (Insecta: Dermaptera: Labiduridae)

Yoshitaka Kamimura, Yoko Matsumura, Chin Cheng Scotty Yang, Stanislav N. Gorb

Research output: Contribution to journalArticlepeer-review

Abstract

Animals can show bias in their use of laterally paired organs that do not have any conspicuous anatomical differentiation between the right and left organs. Like right handedness in humans, males of the giant earwig Labidura riparia (Labiduridae: Labidurinae) preferentially (~90%) use the right one of their laterally paired penises for copulation. To elucidate the evolutionary origin of this lateralization, patterns of penis use were examined for the related species of the genus Nala (Labiduridae: Nalinae). In multiple populations and broods of both Nala lividipes and Nala nepalensis, males that were ready to use the right or left penis were equally frequent, providing a striking contrast to Labidura. Surgical ablation of one of the two penises revealed that both penises are functionally competent in N. lividipes. Nevertheless, each male almost consistently used only one of the paired penises, either the right or the left one. Changes in penis use were estimated to occur only once per 64-143 days per male. The present study is the first report of individual-level lateralization for animal genitalia that do not show any conspicuous anatomical differentiation between the right and left organs. Possible advantages of lateralization are discussed in relationship to co-evolution of the genitalia between the sexes.

Original languageEnglish
Pages (from-to)716-731
Number of pages16
JournalBiological Journal of the Linnean Society
Volume134
Issue number3
DOIs
Publication statusPublished - 2021 Nov 1

Keywords

  • antisymmetry
  • behavioural asymmetry
  • individual-level lateralization
  • mating behaviour
  • penis-number evolution
  • sperm storage organs

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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