The Isolating Potential of a Post-Insemination Barrier to Fertilization

霍华德9407229实现对生殖隔离(近亲物种之间缺乏成功的杂交)的进化和本质的理解是生物学家的一个基本目标。这个目标一直难以实现，反映出识别和描述导致生殖隔离的性状(S)的难度。只有着眼于在生态和进化上具有良好特征的密切相关物种的长期研究，才有可能提供重要的新见解。之前对平地蟋蟀AlLonemobius Fasciatus和A.Socius的大量研究表明，这两个姐妹物种是通过交配后操作的受精障碍进行生殖隔离的。虽然直到最近才首次描述这种类型的生殖障碍，但随着越来越多的研究表明许多密切相关的陆地动物是以这种方式隔离的，这种类型的生殖障碍已经开始引起生物学家的极大关注。在本文提出的工作中，将通过研究这两个物种的交配模式、受精障碍的强度以及障碍的遗传基础来进一步表征筋膜亚种和社会亚种之间的受精障碍。这些研究的结果将被用于构建交配后受精障碍的生殖隔离潜力的计算机模拟模型。对受精屏障隔离潜力的实验室测试将对计算机模拟结果提供重要的检验。这项提案中描述的工作探索了物种形成研究的一个新领域--交配后受精障碍在密切相关物种的生殖隔离中所起的作用。与此同时，这项工作将与生物学中的一场古老的辩论有关，即生殖隔离是通过许多基因的小效应突变(微突变)出现的，还是通过一个或几个基因的大效应突变(大突变)产生的。这项拟议的工作在农业和保护生物学两个应用领域具有重要意义。蟋蟀科包括一些非常严重的农业害虫。这项拟议的研究将提供急需的有关蟋蟀生殖生物学的信息--这些信息可以用来帮助开发生物防治计划。在保护生物学中，稀有物种的完整性经常受到与更常见的姐妹物种的杂交的威胁。因此，了解生殖障碍是如何运作的，对于防止生物多样性的丧失至关重要。

Howard 9407229 Achieving an understanding of the evolution and the nature of reproductive isolation (lack of successful interbreeding between closely related species) is a fundamental goal of biologists. The goal has been elusive, reflecting the difficulty of identifying and characterizing the trait(s) responsible for the onset of reproductive isolation. Only long term studies focusing on closely related species that have been well characterized ecologically and evolutionarily are likely to provide important new insights. A large amount of previous work on the ground crickets Allonemobius fasciatus and A. socius indicates that these sister species are reproductively isolated by a barrier to fertilization that operates after mating. Although described for the first time only recently, this type of reproductive barrier has begun to attract a great deal of attention from biologists as an increasing number of studies indicate that many closely related terrestrial animals are isolated in such a way. In the work proposed here, the barrier to fertilization between A. fasciatus and A. socius will be further characterized by studying patterns of mating in both species, the strength of the barrier to fertilization, and the genetic basis of the barrier. The results of these studies will be used to construct computer simulation models of the reproductive isolating potential of a post-mating barrier to fertilization. A laboratory test to the isolating potential of the fertilization barrier will provide an important check on the computer simulation results. The work described in this proposal explores a new area in speciation research--the role played by post-mating barriers to fertilization in the reproductive isolation of closely related species. At the same time, the work will have bearing on an old debate in biology, whether reproductive isolation arised through mutations of small effect (micromutations) at many genes, or through mutations with large effects (macromutations) at one or a few genes. The proposed work has important implications in two applied fields--agriculture and conservation biology. The family Gryllidae (crickets) includes some very serious agricultural pests. The proposed research will provide badly needed information on reproductive biology of crickets--information that can be used to help develop biological control programs. In conservation biology, the integrity of rare species is often threatened by hybridization with more common sister species. Hence, achieving an understanding of how reproductive barriers operate is critical for preventing the loss of biological diversity.