PDF(Pubmed)
Abstract：
When males compete, sexual selection favors reproductive traits that increase their mating or fertilization success (pre- and postcopulatory sexual selection). It is assumed that males face a trade-off between these 2 types of sexual traits because they both draw from the same pool of resources. Consequently, allocation into mate acquisition or ejaculation should create similar trade-offs with other key life history traits. Tests of these assumptions are exceedingly rare. Males only ejaculate after they mate, and the costs of ejaculation are therefore highly confounded with those of mating effort. Consequently, little is known about how each component of reproductive allocation affects a male\'s future performance. Here, we ran an experiment using a novel technique to distinguish the life history costs of mating effort and ejaculation for mosquitofish (Gambusia holbrooki). We compared manipulated males (mate without ejaculation), control males (mate and ejaculate), and naïve males (neither mate nor ejaculate) continuously housed with a female and 2 rival males. We assessed their growth, somatic maintenance, mating and fighting behavior, and sperm traits after 8 and 16 weeks. Past mating effort significantly lowered a male\'s future mating effort and growth, but not his sperm production, while past sperm release significantly lowered a male\'s future ejaculate quantity, but not his mating effort. Immune response was the only trait impacted by both past mating effort and past ejaculation. These findings challenge the assumption that male reproductive allocation draws from a common pool of resources to generate similar life history costs later in life. Instead, we provide clear evidence that allocation into traits under pre- and postcopulatory sexual selection have different trait-specific effects on subsequent male reproductive performance.
摘要：
当雄性竞争时，性选择有利于增加其交配或受精成功的生殖特征（交配前和交配后的性选择）。假设男性在这两种性特征之间面临权衡，因为他们都来自同一资源池。因此,分配到伴侣获取或射精中应该与其他关键生活史特征产生类似的权衡。对这些假设的测试非常罕见。雄性只在交配后射精，因此，射精的成本与交配的成本高度混淆。因此,关于生殖分配的每个组成部分如何影响男性未来的表现，人们知之甚少。这里,我们使用一种新技术进行了一项实验，以区分蚊子（Gambusiaholbrooki）的交配努力和射精的生活史成本。我们比较了被操纵的雄性(没有射精的交配)，控制男性（交配和射精），天真的雄性（既不交配也不射精）连续与雌性和2个敌对雄性住在一起。我们评估了他们的成长，躯体维持,交配和战斗行为，8周和16周后的精子性状。过去的交配努力显著降低了男性未来的交配努力和生长，但不是他的精子生产，虽然过去的精子释放显着降低了男性未来的射精量，但不是他的交配努力。免疫反应是受过去交配努力和过去射精影响的唯一特征。这些发现挑战了以下假设：男性生殖分配从共同的资源库中汲取，以在以后的生活中产生类似的生活史成本。相反，我们提供了明确的证据，即在交配前和交配后性选择下分配到性状对随后的男性生殖表现具有不同的性状特异性影响。
