Direct Assessment of Natural Selection in a Hybrid Zone

9509742希尔比什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区内和区外的扩散，以及它们不同的生存和繁殖。强大的选择在能够大规模扩散的海洋贻贝物种的杂交种群中进行。这里提出的工作目标有两个。首先，杂交区的选择是由环境决定的这一假设将得到检验，并确定潜在的选择因素。其次，将描述幼虫在杂交区的一部分的扩散模式。这将有助于确定迁入杂交种群并随后接受选择的幼虫的地理和遗传来源。将检验四个假设，以了解特定环境因素在杂交基因型间选择中的作用。这些研究将确定每种环境压力与自然选择的开始和持续时间的一致性。这些研究将为未来研究中潜在的选择剂的具体实验室和现场实验测试提供基础。其次，在以前NSF支持下开发的分子遗传技术将被用来确定招募到杂交种群的幼虫种群的起源。这些信息将为解释杂交种群内观察到的选择模式提供基础，并可能在杂交幼虫离开杂交区域返回亲本种群时解释它们的命运。

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.