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Males Use Multiple, Redundant Cues to Detect Mating Rivals

2011; Elsevier BV; Volume: 21; Issue: 7 Linguagem: Inglês

10.1016/j.cub.2011.03.008

1879-0445

Amanda Bretman, James D. Westmancoat, Matthew J. G. Gage, Tracey Chapman,

Insect and Arachnid Ecology and Behavior

Across many species, males exhibit plastic responses when they encounter mating rivals [1Wedell 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]. The ability to tailor responses to the presence of rivals allows males to increase investment in reproduction only when necessary. This is important given that reproduction imposes costs [2Dewsbury D.A. Ejaculate cost and male choice.Am. Nat. 1982; 119: 601-610Crossref Scopus (798) Google Scholar] that limit male reproductive capacity, particularly when sperm competition occurs [3Birkhead T.R. Møller A.P. Sperm competition and sexual selection. Academic Press, London1998Google Scholar, 4Simmons L.W. Sperm competition and its evolutionary consequences in the insects. Princeton University Press, Princeton, New Jersey2001Google Scholar]. Fruitfly (Drosophila melanogaster) males exposed to rivals subsequently mate for longer and thus accrue fitness benefits under increased competition [5Bretman A. Fricke C. Chapman T. Plastic responses of male Drosophila melanogaster to the level of sperm competition increase male reproductive fitness.Proc. Biol. Sci. 2009; 276: 1705-1711Crossref PubMed Scopus (163) Google Scholar], in line with theory [6Parker G.A. Ball M.A. Stockley P. Gage M.J.G. Sperm competition games: Individual assessment of sperm competition intensity by group spawners.Proc. Biol. Sci. 1996; 263: 1291-1297Crossref Scopus (250) Google Scholar, 7Parker G.A. Ball M.A. Stockley P. Gage M.J.G. Sperm competition games: A prospective analysis of risk assessment.Proc. Biol. Sci. 1997; 264: 1793-1802Crossref PubMed Scopus (308) Google Scholar]. Here, we show that male D. melanogaster detect rivals by using a suite of cues and that the resulting responses lead directly to significant fitness benefits. We used multiple techniques to systematically remove auditory, olfactory, tactile, and visual cues, first singly and then in all possible combinations. No single cue alone was sufficient to allow males to detect rivals. However, the perception of any two cues from sound, smell, or touch permitted males to detect and respond adaptively to rivals through increased offspring production. Vision was only of marginal importance in this context. The findings indicate adaptive redundancy through the use of multiple, but interchangeable, cues. We reveal the robust mechanisms by which males assess their socio-sexual environment to precisely attune responses via the expression of plastic behavior.