Landry C, Geyer L B, Arakaki Y, Uehara T, Palumbi Stephen R
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
Proc Biol Sci. 2003 Sep 7;270(1526):1839-47. doi: 10.1098/rspb.2003.2395.
The rich species diversity of the marine Indo-West Pacific (IWP) has been explained largely on the basis of historical observation of large-scale diversity gradients. Careful study of divergence among closely related species can reveal important new information about the pace and mechanisms of their formation, and can illuminate the genesis of biogeographic patterns. Young species inhabiting the IWP include urchins of the genus Echinometra, which diverged over the past 1-5 Myr. Here, we report the most recent divergence of two cryptic species of Echinometra inhabiting this region. Mitochondrial cytochrome oxidase 1 (CO1) sequence data show that in Echinometra oblonga, species-level divergence in sperm morphology, gamete recognition proteins and gamete compatibility arose between central and western Pacific populations in the past 250 000 years. Divergence in sperm attachment proteins suggests rapid evolution of the fertilization system. Divergence of sperm morphology may be a common feature of free-spawning animals, and offers opportunities to simultaneously understand genetic divergence, changes in protein expression patterns and morphological evolution in traits directly related to reproductive isolation.
西太平洋-印度洋（IWP）丰富的物种多样性很大程度上是基于对大规模多样性梯度的历史观察来解释的。对近缘物种之间差异的仔细研究可以揭示有关其形成速度和机制的重要新信息，并能够阐明生物地理模式的起源。栖息在IWP的年轻物种包括艾氏海胆属的海胆，它们在过去100万至500万年中发生了分化。在此，我们报告了栖息在该地区的两种隐存艾氏海胆物种的最新分化情况。线粒体细胞色素氧化酶1（CO1）序列数据表明，在长海胆中，过去25万年里，太平洋中部和西部种群之间在精子形态、配子识别蛋白和配子兼容性方面出现了物种水平的差异。精子附着蛋白的差异表明受精系统的快速进化。精子形态的差异可能是自由产卵动物的一个共同特征，为同时理解遗传差异、蛋白质表达模式的变化以及与生殖隔离直接相关的性状的形态进化提供了机会。
