Sexual dimorphism in amphipods: the role of male posterior gnathopods revealed in Gammarus pulex

Kevin D. Hume, Robert W. Elwood, Jaimie T.A. Dick, Jenny Morrison

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

In the mate-guarding amphipod, Gammarus pulex, the enlarged male posterior gnathopods have been variously suggested to function to grasp and subdue the female, to be used as weapons in fights between males, to signal to the female the male presence and stimulate moult accelaration, egg development or egg extrusion. These hypotheses were tested in a series of experiments, the results of which reveal an unexpected function. Ablation of the posterior gnathopods of males showed that they were neither necessary for, nor advantageous in, establishment and/ or maintenance of precopula mate guarding, with or without competition with intact males. Furthermore, these appendages do not function to advance female moult, or stimulate egg development or extrusion. However, only males with intact posterior gnathopods were able to copulate. We also show that females require a full copulation of several bouts to extrude eggs. We conclude that the function of the posterior gnathopods is to facilitate copulation and suggest future studies focus on the selective pressures acting on copulating males.
Original languageEnglish
Pages (from-to)264-269
Number of pages6
JournalBehavioral Ecology and Sociobiology
Volume58
Issue number3
DOIs
Publication statusPublished - Jul 2005

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Ecology
  • Behavioral Neuroscience

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