Marine Bio-Tech Fellowship: Variation in a Gamete Recognition Protein of Pacific Sand Dollars

小行星9321243 海洋无脊椎动物的密切相关物种通常一起出现，并经常同时产卵，但这些物种之间的杂交很少形成。 配子表面的蛋白质控制物种特异性受精。 有三条证据表明，这些配子识别蛋白的变化可能与生殖隔离的进化有关：1）不能生育的异种杂交通常是由于精子不能附着在异种卵上，2）近缘的、生殖隔离的物种通常表现出很少的总体遗传差异，和3）选择促进了在不同种类的鲍鱼中发现的精子携带的配子识别蛋白的分化。该项目将研究两个关键问题仍然没有答案：1）种间配子识别蛋白的差异是否在物种重叠的地理区域最大，以及2）物种内配子识别蛋白的变异程度如何？ 这两个问题将通过记录共同发生的和孤立的太平洋沙元种群的精子携带的配子识别蛋白bindin的核苷酸序列变异来解决。 的 该项目将集中于Dendraster属的成员，其地理分布（重叠和非重叠区域）和最近的起源（5月1日）应该有助于区分驱动结合蛋白分歧的替代进化机制。 最后，结合蛋白的种间和种内变异的功能意义将使用成对受精试验进行研究。 这项研究项目应产生新的见解的作用，促进配子识别蛋白的分歧种间杂交的潜力。 ***

9321243 Hellberg Closely related species of marine invertebrates commonly occur together and often spawn simultaneously, yet hybrids between these species rarely form. Proteins on the surface of the gametes control species-specific fertilization. Three lines of evidence suggest that changes in these gamete recognition proteins may be involved in the evolution of reproductive isolation: 1) non-fertile heterospecific crosses usually result from the failure of sperm to attach to heterospecific eggs, 2) closely related, reproductively isolated species often show little overall genetic divergence, and 3) selection promotes the divergence of sperm-borne gamete recognition proteins found in different species of abalone. This project will examine two critical questions which remain unanswered: 1) Are interspecific differences in gamete recognition proteins greatest in geographical areas of species overlap, and 2) How variable are gamete recognition proteins within species? These two questions will be addresses by documenting nucleotide sequence variation of the sperm borne gamete recognition protein bindin from both co-occurring and isolated populations of Pacific sand dollars. The project will focus on members of the genus Dendraster, whose geographical distribution (both overlapping and non- overlapping regions) and very recent origins (1 May) should facilitate discrimination between alternative evolutionary mechanisms driving bindin divergence. Finally, the functional significance of both inter-and intraspecific variation in bindin will be examined using pairwise fertilization assays. This research project should produce novel insights into the role of the potential for interspecific hybridization in promoting the divergence of gamete recognition proteins. ***