Sea stars, sperm, and sexual selection: how mating systems affect adapative and neutral molecular evolution

动物的有性繁殖会对它们的基因变异产生强烈的影响，而这种影响的大小通常取决于性行为发生的方式。我在一群海星（被称为asterinids或cushion stars）中研究了性与基因之间的关系，这些海星进化出了惊人的各种生殖特征，比如高风险的性行为，包括释放大量微小的卵子和精子；保护育雏和活产；兄弟姐妹吃人;变性;和自体受精。有些“垫星”具有这些特征的组合，这应该使它们能够避免近亲繁殖（及其对健康的不良后果），但也可能使它们受到激烈的性选择，因为雄性之间竞争使雌性的卵子受精。其他软垫星有这些特征的其他组合，应该会放松这种性选择（因为雄性也是雌性，并使自己的卵受精），但也使它们倾向于非常强的近亲繁殖（因为父母与自己交配，他们的后代很少在种群之间移动）。我的研究旨在通过观察不同类别的基因，了解物种之间的性别差异是如何影响近亲繁殖和性选择的，这些基因主要对一个或另一个过程做出反应。因为性选择和近亲繁殖都可能导致种群差异，从而导致新物种的形成，对这两个过程的作用的理解可以帮助我们理解物种形成和生物多样性的起源。这些结果对其他研究领域也很有趣，也很重要，包括动物育种和人类种群生物学，近亲繁殖和性选择都是重要的（有时是竞争的）进化过程。

Sexual reproduction by animals can have a strong effect on their genetic variation, and the size of this effect often depends on exactly how sex happens. I study this relationship between sex and genetics in a group of sea stars (called asterinids or cushion stars) that have evolved an astounding variety of reproductive traits such as high-risk sexual behaviour involving the release of vast numbers of tiny eggs and sperm; brood protection and live birth; sibling cannibalism; sex-change; and self-fertilization. Some cushion stars have combinations of these traits that should allow them to avoid inbreeding (and its bad consequences for fitness), but might also subject them to intense sexual selection due to competition among males to fertilize the eggs of females. Other cushion stars have other combinations of these traits that should relax this kind of sexual selection (because males are also females, and fertilize their own eggs), but also predispose them to very strong inbreeding (because the parents mate with themselves, and their offspring rarely move between populations). My research is designed to understand how these sexual differences among species affect both inbreeding and sexual selection by looking at different classes of genes that are expected to mainly respond to one or the other process. Because both sexual selection and inbreeding can cause population differences that lead to the formation of new species, an understanding of the role of these two processes can help us understand speciation and the origins of biodiversity. The results are also interesting and important for other areas of research, including animal breeding and human population biology, in which both inbreeding and sexual selection are important (sometimes competing) evolutionary processes.