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

动物的有性繁殖可能会对它们的基因变异产生强烈的影响，而这种影响的大小往往取决于性行为的确切方式。我在一群海星(称为小行星或垫星)中研究性和遗传学之间的这种关系，这些海星进化出了令人震惊的各种生殖特征，例如释放大量微小卵子和精子的高风险性行为；孵化保护和活产；兄弟姐妹同类相食；性别变化；以及自我受精。一些垫星拥有这些特征的组合，这应该会让它们避免近亲交配(及其对健康的不良后果)，但也可能会让它们受到激烈的性别选择，因为雄鸟之间会竞争让雌性海星的卵受精。其他垫星也有这些特征的其他组合，这应该会放松这种性选择(因为雄性也是雌性，让自己的卵受精)，但也使它们容易进行非常强烈的近亲交配(因为父母与自己交配，他们的后代很少在种群之间流动)。我的研究旨在通过观察预计主要对其中一个过程做出反应的不同类别的基因，来了解物种之间的性别差异如何影响近亲交配和性选择。由于性选择和近亲交配都会导致种群差异，从而导致新物种的形成，因此了解这两个过程的作用可以帮助我们理解物种形成和生物多样性的起源。这一结果对包括动物育种和人类种群生物学在内的其他研究领域也很有趣和重要，在这些领域中，近亲交配和性选择都是重要的(有时是相互竞争的)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.