Fu P, Neff B D, Gross M R
Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5R 1G6.
Proc Biol Sci. 2001 Jun 7;268(1472):1105-12. doi: 10.1098/rspb.2001.1625.
Sperm competition is a major force in sexual selection, but its implications for mating-system and life-history evolution are only beginning to be understood. The well-known sneak-guard model predicts that sneaks will win in sperm competition. We now provide empirical confirmation of this prediction. Bluegill sunfish (Lepomis macrochirus) have both sneak (cuckolder) and guard (parental) males. Guards make nests, court females and provide solitary parental care for the embryos. Sneaks include small cuckolders, which are termed 'sneakers', that dart in and out of nests in order to ejaculate between the spawning pair and larger cuckolders, which are termed 'satellites', that mimic females in order to ejaculate between the spawning pair. Using field behavioural data, genetic data and new mathematical models for paternity analyses, we show, for the first time to the authors' knowledge, that sneaks fertilize more eggs than guards during sperm competition. In addition, we show that sneakers are superior to satellites in sperm competition and, thus, that even among sneaks there are tactic-specific differences in competitive success.
精子竞争是性选择中的一股主要力量，但其对交配系统和生活史进化的影响才刚刚开始被理解。著名的偷袭者-守卫者模型预测，偷袭者将在精子竞争中获胜。我们现在为这一预测提供了实证依据。蓝鳃太阳鱼（Lepomis macrochirus）既有偷袭型（戴绿帽者）雄性，也有守卫型（亲代）雄性。守卫型雄性筑巢、追求雌鱼并为胚胎提供单独的亲代照料。偷袭者包括体型较小的戴绿帽者，被称为“偷情者”，它们会冲进和冲出巢穴，以便在产卵的雌雄鱼之间射精；还有体型较大的戴绿帽者，被称为“卫星鱼”，它们模仿雌鱼，以便在产卵的雌雄鱼之间射精。利用野外行为数据、基因数据以及用于亲权分析的新数学模型，据作者所知，我们首次表明，在精子竞争中，偷袭者使卵子受精的数量多于守卫者。此外，我们还表明，偷情者在精子竞争中优于卫星鱼，因此，即使在偷袭者中，竞争成功也存在特定策略上的差异。
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