Direct Assessment of Natural Selection in a Hybrid Zone

小行星9509742 杂交区的动态由两个主要因素组成：亲本物种及其杂交种在杂交区内外的扩散，以及它们的差异生存和繁殖。强选择在能够大规模扩散的海洋贻贝物种的杂交种群中起作用。这里提出的工作目标有两个方面。 首先，假设在混合区的选择是由环境决定的，将进行测试和潜在的选择剂确定。 其次，将描述幼虫在杂交区的一部分扩散的模式。 这将有助于确定迁移到杂交种群并随后进行选择的幼虫的地理和遗传起源。 四个假设将进行检查，以了解特定的环境因素在杂交基因型之间的选择的作用。 这些研究将确定每种环境压力与自然选择的发生和持续时间的一致性。 这些研究将为未来研究中对潜在选择剂的特定实验室和现场实验测试提供基础。 第二，分子遗传技术，开发与以前的NSF的支持，将用于确定幼虫种群的起源，招募到杂交种群。 这些信息将提供一个基础上，以解释模式的选择观察到的杂交种群和潜在的命运杂交幼虫一旦他们分散出杂交区回到一个亲本种群。

9509742 Hilbish The dynamics of hybrid zones consist of two major elements; the dispersal of parent species and their hybrids into and out of the zone, and their differential survival and reproduction. Strong selection operates within hybrid populations of marine mussels species capable of large-scale dispersal. The objectives of the work proposed here is two-fold. First, the hypothesis that selection in the hybrid zone is determined by the environment will be tested and potential selective agents identified. Second, the patterns of larval dispersal across a portion of the hybrid zone will be described. This will serve to identify the geographic and genetic origin of larvae that immigrate to hybrid populations and are subsequently subjected to selection. Four hypotheses will be examined to understand the role of specific environmental factors in selection among hybrid genotypes. These studies will determine the coincidence of each environmental stress with onset and duration of natural selection. These studies will provide the basis for specific laboratory and field-experimental tests of potential selective agents in future studies. Second, molecular genetic techniques, developed with previous NSF support, will be used to determine the origin of larval populations that recruit into hybrid populations. This information will provide a foundation upon which to interpret the patterns of selection observed within hybrid populations and potentially the fate of hybrid larvae once they disperse out of the hybrid zone back into one of the parental populations.