Grant: Discovery Development Grant

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.