The Genetics of Reproductive Isolation: Co-Evolution, Polymorphism and Functional Differentiation of Gamete Recognition Loci in Sea Urchins

9510407帕伦比了解物种起源一直是生物学中最重要但也是最困难的挑战之一。在我们对物种起源的理解中，最大的差距之一涉及到伴随着生殖隔离而产生的基因变化。这项提议描述了在这样一个新兴的模型系统中进行的新实验：棘球藻属最近分化的海胆中的高度可变配子附着基因。由于精子不能与不同物种的卵子融合，这些物种被生殖隔离。我们先前的工作表明，精子附着蛋白Bindin在棘尾虫物种之间有很大的差异，并且在物种之间存在广泛的差异。由于在海胆受精的分子生物学方面开展了积极的工作，我们现在还可以检查卵子受体的基因，并首次研究参与生殖隔离的相互作用基因的共同进化。我们将通过对Enhinometra中的鸡蛋受体基因进行测序，并将结果与我们现有的结合素序列进行比较，来检验结合素/受体的共同进化。4个印度-太平洋棘球绦虫物种的cdna序列将被用来测试在结合中观察到的模式。这些结果将使我们能够理解蛋白质的共同进化，这些蛋白质与定义物种边界的机制密切相关。我们的研究对受精机制以及卵子和精子如何成功识别彼此的基础研究也很重要。

9510407 PALUMBI Understanding how species originate has been one of the most important, yet one of the most difficult, challenges in biology. One of the largest gaps in our understanding of the origin of species concerns the genetic changes that accompany reproductive isolation. This proposal describes new experiments in one such emerging model system: hyper-variable gamete attachment genes in recently diverged sea urchins in the genus Echinometra. These species are reproductively isolated by the failure of sperm to fuse with eggs of different species. Our prior work has shown that the sperm attachment protein bindin has diverged greatly between Echinometra species, and is extensively variable within species. Because of active work on the molecular biology of sea urchin fertilization, we can now also examine the gene for the egg receptor, and for the first time study the co-evolution of interacting genes involved in reproductive isolation. We will examine bindin/receptor co-evolution by sequencing the egg receptor gene in Enhinometra and comparing results to our existing bindin sequences. cDNA sequences of the 4 Indo-Pacific Echinometra species will be used to test for patterns observed in bindin. The results will allow us to understand the co-evolution of proteins that are closely involved in the mechanisms that define species boundaries. Our studies are also important for basic research on mechanisms of fertilization, and how egg and sperm successfully recognize one another.