Mechanisms and implications of gametic incompatibilities in whales

什么样的遗传特征使一个精子比其他精子更有优势，从而使卵子受精？这些效应如何影响种群内生殖成功的总体遗传特征和模式？这些是推动拟议研究的主要问题。受精是由精子和卵子之间的一系列复杂的相互作用介导的，其中的关键步骤需要每个配子上表达的蛋白质之间的互补相互作用。这些蛋白质影响精子和卵子在成功受精的潜力方面的兼容性，这通常被称为它们的配子兼容性。我建议在两个不同的系统中进行配子相容性基因的序列分析。首先，北大西洋露脊鲸是一种濒危物种，其受精偏向于遗传上不同的配子，并且恢复潜力受到生殖性能降低的限制。然而，偏受精模式的机制，限制繁殖的因素，是未知的。其次，江豚代表了两个最近才彼此分离的物种，因此为研究生殖障碍的进化提供了一个有用的系统。对于北大西洋露脊鲸，我将测试两个假设：1）这些基因的等位基因的差异相容性驱动受精模式; 2）这些基因的低变异性限制了繁殖性能和恢复潜力。对于江豚，我将检验配子相容性基因的分化是江豚最近物种形成过程中重要的生殖障碍的假设。这项研究代表了第一次有机会研究哺乳动物中的互补配子相容性基因，因此将在生殖生物学，保护遗传学和物种形成领域产生重大影响。对于生殖生物学，非随机受精的模式在自然界中广泛存在，但其潜在机制仍然难以捉摸。我将解决这个问题，并确定互补基因的基因型如何相互作用，导致非随机受精模式。对于保护遗传学，降低生殖性能往往与低水平的遗传变异性，但涉及的机制往往是未知的。我将通过确定这些基因的特征如何影响濒危物种的繁殖成功和恢复潜力来解决这个问题。对于物种形成，新物种如何进化的研究通常围绕着生殖障碍的进化。配子相容性基因通常被认为起着重要的作用，然而，很少有数据可以用来检验这一假设。我将通过测试这些基因在最近的物种形成事件中生殖障碍发展中的作用，提供一些急需的数据。

What genetic characteristics give one sperm an advantage over the others, allowing it to fertilize the egg? How do such effects influence the overall genetic characteristics and patterns of reproductive success within a population? These are the main questions driving the proposed research. Fertilization is mediated by a complex series of interactions between the sperm and the egg, key steps of which require complimentary interactions between proteins expressed on each gamete. These proteins influence how compatible a sperm and egg are, in terms of potential for successful fertilization, which is often referred to as their gametic compatibility. I propose to conduct sequence analyses of gamete compatibility genes in two different systems. First, the North Atlantic right whale is an endangered species where fertilizations are biased towards genetically dissimilar gametes, and recovery potential is limited by reduced reproductive performance. However, the mechanisms biasing fertilization patterns, and the factors limiting reproduction, are unknown. Second, finless porpoises represent two species that split from each other very recently, and therefore provide a useful system for studying the evolution of reproductive barriers. For the North Atlantic right whale I will test two hypotheses: 1) that differential compatibility of alleles at these genes drives patterns of fertilization; and 2) that low variability at these genes is limiting reproductive performance and recovery potential. For the finless porpoise, I will to test the hypothesis that differentiation at gamete compatibility genes represented an important reproductive barrier during their recent speciation. This study represents the first opportunity to study complimentary gamete compatibility genes in mammals, and will therefore have large impacts in the fields of reproductive biology, conservation genetics, and speciation. For reproductive biology, patterns of non-random fertilization are widespread in nature, but the underlying mechanisms remain elusive. I will address this issue and identify how genotypes at complimentary genes interact to result in non-random fertilization patterns. For conservation genetics, reduced reproductive performance is often associated with low levels of genetic variability, but the mechanisms involved are often unknown. I will address this issue by establishing how characteristics at these genes influence reproductive success and recovery potential of an endangered species. For speciation, the study of how new species evolve often centres around the evolution of reproductive barriers. Gamete compatibility genes are often presumed to play an important role; however, few data are available to test this hypothesis. I will provide some much needed data by testing the role of these genes in the development of reproductive barriers during a recent speciation event.