An Experimental Study of the Role of Gamete Recognition in Reproductive Isolation

9707220 Palumbi受精成功变异的遗传基础将通过检查一种被充分研究的沿海海洋无脊椎动物的卵子和精子的相互作用来确定。先前对夏威夷海胆（Echinometra mathaei）的研究表明，不同的雄性海胆拥有一种决定精子与卵子附着的基因的不同等位基因。这项拟议中的研究将确定具有不同等位基因的雄性是否拥有具有不同附着特性的精子，以及具有特定等位基因的雄性的精子是否更容易使卵子受精。我们将结合不同雄性受精成功的显微测定，以及精子与卵子实际受精的PCR测定来确定精子附着位点的遗传变异对受精成功的影响程度。卵子和精子的相互作用对成功受精至关重要，但也是最难研究的生物学过程之一。不同雄性动物使同一雌性动物的卵子受精的能力有时差异很大，但我们不知道是什么类型的机制导致了这种差异。最近，研究表明，在一些物种中，不同的雄性在决定精子与卵子附着方面的基因位点上存在遗传差异，这为首次研究受精差异的遗传基础提供了有力的系统。研究结果将阐明自然选择如何在自然种群中维持受精多态性，并可能有助于解释涉及配子相互作用的遗传位点上快速而新颖的分子进化模式。

9707220 Palumbi The genetic basis for variation in fertilization success will be determined by examining the interaction of eggs and sperm from a well-studied species of coastal marine invertebrate. Prior work on this species, the Hawaiian sea urchin Echinometra mathaei, has shown that different males possess different alleles for a gene that determines the attachment of sperm to eggs. The proposed research will determine whether males with different alleles have sperm with different attachment properties, and if eggs tend to be fertilized better by sperm from males with particular alleles. We will use a combination of microscopic eterminations of fertilization success of different males, and a PCR assay of which sperm actually fertilize which eggs to determine the degree to which genetic variation at the sperm attachment locus influences fertilization success. The interaction of eggs and sperm is crucial to successful fertilization, yet is one of the most difficult biological processes to study. The ability of different males to fertilize eggs from a particular female sometimes varies enormously, but we have little idea what types of mechanisms might cause this variation. Recently, it has been shown in some species that different males differ genetically at loci that determine aspects of sperm-egg attachment, and this provides a powerful system to investigate for the first time the genetic basis for differences in fertilization. The results will illuminate how natural selection might be acting to maintain fertilization polymorphisms in natural populations, and may help explain the rapid and novel patterns of molecular evolution at genetic loci involving gamete interactions.