Schärer Lukas
University of Basel, Zoological Institute, Evolutionary Biology, Vesalgasse 1, 4051 Basel, Switzerland.
Evolution. 2009 Jun;63(6):1377-405. doi: 10.1111/j.1558-5646.2009.00669.x. Epub 2009 Feb 24.
Sex allocation is a crucial life-history parameter in all sexual organisms. Over the last decades a body of evolutionary theory, sex allocation theory, was developed, which has yielded capital insight into the evolution of optimal sex allocation patterns and adaptive evolution in general. Most empirical work, however, has focused on species with separate sexes. Here I review sex allocation theory for simultaneous hermaphrodites and summarize over 50 empirical studies, which have aimed at evaluating this theory in a diversity of simultaneous hermaphrodites spanning nine animal phyla. These studies have yielded considerable qualitative support for several predictions of sex allocation theory, such as a female-biased sex allocation when the number of mates is limited, and a shift toward a more male-biased sex allocation with increasing numbers of mates. In contrast, many fundamental assumptions, such as the trade-off between male and female allocation, and numerous predictions, such as brooding limiting the returns from female allocation, are still poorly supported. Measuring sex allocation in simultaneously hermaphroditic animals remains experimentally demanding, which renders evaluation of more quantitative predictions a challenging task. I identify the main questions that need to be addressed and point to promising avenues for future research.
性别分配是所有有性生物中一个至关重要的生活史参数。在过去几十年里，形成了一系列进化理论——性别分配理论，这一理论为最优性别分配模式的进化以及整体的适应性进化提供了重要见解。然而，大多数实证研究都集中在雌雄异体的物种上。在此，我回顾了关于同步雌雄同体生物的性别分配理论，并总结了50多项实证研究，这些研究旨在评估这一理论，研究对象涵盖了九个动物门的多种同步雌雄同体生物。这些研究为性别分配理论的若干预测提供了相当多的定性支持，比如当配偶数量有限时偏向雌性的性别分配，以及随着配偶数量增加向更偏向雄性的性别分配转变。相比之下，许多基本假设，比如雄性和雌性分配之间的权衡，以及众多预测，比如育雏限制雌性分配的回报，仍然缺乏有力支持。在同步雌雄同体动物中测量性别分配在实验上仍然具有挑战性，这使得评估更具定量性的预测成为一项艰巨任务。我确定了需要解决的主要问题，并指出了未来研究的有前景的方向。
