Developmental temperature affects the expression of ejaculatory traits and the outcome of sperm competition in Callosobruchus maculatus

The outcome of post-copulatory sexual selection is determined by a complex set of interactions between the primary reproductive traits of two or more males and their interactions with the reproductive traits of the female. Recently a number of studies have shown the primary reproductive traits of both males and females express phenotypic plasticity in response to the thermal environment experienced during ontogeny. However, how plasticity in these traits affects the dynamics of sperm competition remains largely unknown. Here we demonstrate plasticity in testes size, sperm size and sperm number in response to developmental temperature in the bruchid beetle Callosobruchus maculatus. Males reared at the highest temperature eclosed at the smallest body size and had the smallest absolute and relative testes size. Males reared at both the high and low temperature extremes produced both fewer and smaller sperm than males reared at intermediate temperatures. In the absence of sperm competition ...

交配后性选择（post-copulatory sexual selection）的结果由两个或多个雄性的主要繁殖性状之间的复杂相互作用，以及这些性状与雌性繁殖性状的相互作用共同决定。近期多项研究表明，雌雄两性的主要繁殖性状会针对个体发育（ontogeny）过程中经历的热环境表现出表型可塑性（phenotypic plasticity）。然而，这些性状的可塑性如何影响精子竞争的动态变化，目前仍知之甚少。本研究以斑豆象（Callosobruchus maculatus，豆象科甲虫）为对象，揭示了其睾丸大小、精子大小及精子数量针对发育温度的可塑性。在最高温度下饲养的雄性个体羽化时体型最小，且绝对睾丸大小和相对睾丸大小均为最小。在极端高温和极端低温下饲养的雄性个体，其产生的精子数量少于、体积小于在中等温度下饲养的雄性个体。在无精子竞争的情况下……