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Sperm Viability Matters in Insect Sperm Competition

2005; Elsevier BV; Volume: 15; Issue: 3 Linguagem: Inglês

10.1016/j.cub.2005.01.032

1879-0445

Francisco García‐González, Leigh W. Simmons,

Insect and Arachnid Ecology and Behavior

Experimental studies in insects have shown how sperm competition can be a potent selective force acting on an array of male reproductive traits [1Simmons L.W. Sperm Competition and Its Evolutionary Consequences in the Insects. Princeton University Press, Princeton, New Jersey2001Google Scholar, 2Wedell N. Gage M.J.G. Parker G.A. Sperm competition, male prudence and sperm-limited females.Trends Ecol. Evol. 2002; 17: 313-320Abstract Full Text Full Text PDF Scopus (900) Google Scholar, 3Birkhead T.R. Møller A.P. Sperm Competition and Sexual Selection. Academic Press, San Diego, California1998Google Scholar, 4Smith R.L. Sperm Competition and the Evolution of Animal Mating Systems. Academic Press, New York1984Google Scholar]. However, the role of sperm quality in determining paternity in insects has been neglected, despite the fact that sperm quality has been shown to influence the outcome of sperm competition in vertebrates [5Dziuk P.J. Factors that influence the proportion of offspring sired by a male following heterospermic insemination.Anim. Reprod. Sci. 1996; 43: 65-88Abstract Full Text PDF Scopus (109) Google Scholar, 6Birkhead T.R. Martinez J.G. Burke T. Froman D.P. Sperm mobility determines the outcome of sperm competition in the domestic fowl.Proc. R. Soc. Lond. B. Biol. Sci. 1999; 266: 1759-1764Crossref Scopus (293) Google Scholar, 7Gage M.J.G. Macfarlane C.P. Yeates S. Ward R.G. Searle J.B. Parker G.A. Spermatozoal traits and sperm competition in Atlantic salmon Relative sperm velocity is the primary determinant of fertilization success.Curr. Biol. 2004; 14: 44-47Abstract Full Text Full Text PDF PubMed Google Scholar, 8Donoghue A.M. Sonstegard T.S. King L.M. Smith E.J. Burt D.W. Turkey sperm mobility influences paternity in the context of competitive fertilization.Biol. Reprod. 1999; 61: 422-427Crossref PubMed Scopus (52) Google Scholar]. A recent comparative analysis found that males of polyandrous insect species show a higher proportion of live sperm in their stores [9Hunter F.M. Birkhead T.R. Sperm viability and sperm competition in insects.Curr. Biol. 2002; 12: 121-123Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar]. Here, we test the hypothesis that sperm viability influences paternity at the within-species level. We use the cricket Teleogryllus oceanicus to conduct sperm competition trials involving prescreened males that differ in the viability of their sperm. We find that paternity success is determined by the proportion of live sperm in a male's ejaculate. Furthermore, we were able to predict the paternity patterns observed on the basis of the males' relative representation of viable sperm in the female's sperm-storage organ. Our findings provide the first experimental evidence for the theory that sperm competition selects for higher sperm quality in insects. Between-male variation in sperm quality needs to be considered in theoretical and experimental studies of insect sperm competition.