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Behavioral Ecology and Sociobiology

, Volume 53, Issue 3, pp 190–197 | Cite as

Competition, fluctuating asymmetry and sperm transfer in male gryllid crickets (Gryllus bimaculatus and Gryllodes sigillatus)

  • Samantha T. Mallard
  •  C. Barnard
Original Article
  • 125 Downloads

Abstract.

Sperm competition theory predicts that ejaculate expenditure by males should increase with the risk of competition from rivals. The tendency to modulate expenditure, however, may reflect various constraints acting on different individuals. We test this idea here by looking at the effects of competition and fluctuating asymmetry (FA) in two species of gryllid cricket. Male Gryllus bimaculatus and Gryllodes sigillatus modulated the sperm content of their spermatophores in relation to both apparent competition and FA in limb size. Males of both species increased the amount of sperm transferred when an apparent male competitor was present, sperm number increasing regardless of the species of apparent competitor in G. bimaculatus, but significantly more with a conspecific competitor in G. sigillatus. In addition, the relative size of the spermatophylax in G. sigillatus increased in the presence of apparent competition, while spermatophore transfer time decreased in G. bimaculatus. Sperm number showed opposite relationships with limb asymmetry in the two species, decreasing with increasing asymmetry in males in G. sigillatus, but increasing with asymmetry in both males and females in G. bimaculatus. G. bimaculatus, but not G. sigillatus, also transferred more sperm when paired with a larger female. Relationships between reproductive measures and limb asymmetry were significant only when competitors were present in G. bimaculatus, but were significant regardless of competition in G. sigillatus. The differences may reflect the additional burden of producing a spermatophylax in G. sigillatus.

Competition Fluctuating asymmetry Gryllodes sigillatus Gryllus bimaculatus Sperm 

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Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  • Samantha T. Mallard
    • 1
  •  C. Barnard
    • 1
  1. 1.Animal Behaviour and Ecology Research Group, School of Life and Environmental Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK

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