Section of Integrative Biology, University of Texas at Austin, 1 University Station C0930, Austin, TX 78712, USA.
Biol Lett. 2011 Oct 23;7(5):733-5. doi: 10.1098/rsbl.2011.0286. Epub 2011 Apr 20.
In species with alternative reproductive tactics, males that sneak copulations often have larger, higher quality ejaculates relative to males that defend females or nest sites. Ejaculate traits can, however, exhibit substantial phenotypic plasticity depending on a male's mating role in sperm competition, which may depend on the tactic of his competitor. We tested whether exposure to males of different tactics affected sperm number and quality in the swordtail Xipophorus nigrensis, a species with small males that sneak copulations and large males that court females. Sperm swimming speed was higher when the perceived competitor was small than when the competitor was large. Plasticity, however, was only exhibited by small males. Sperm number and viability were invariant between social environments. Our results suggest sperm quality is role-dependent and that plastic responses to the social environment can differ between male reproductive tactics.
在具有替代繁殖策略的物种中，相对于那些保护雌性或巢穴的雄性，偷偷交配的雄性通常具有更大、更高质量的精液。然而，根据雄性在精子竞争中的交配角色，精液特征可能表现出显著的表型可塑性，而这可能取决于其竞争对手的策略。我们测试了暴露于不同策略的雄性是否会影响具有较小雄性的剑尾鱼（Xipophorus nigrensis）的精子数量和质量，这种鱼的雄性较小，会偷偷交配，而雄性较大，则会求爱雌性。当感知到的竞争对手较小时，精子游动速度较高。然而，只有小雄鱼表现出了这种可塑性。在不同的社会环境中，精子数量和活力保持不变。我们的结果表明，精子质量是依赖于角色的，并且对社会环境的可塑性反应可能因雄性繁殖策略而异。
