Direct Assessment of Natural Selection in a Hybrid Zone

[509742] Hilbish混合区动力学包括两个主要因素；亲本物种及其杂交种在该区内外的扩散，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，杂交区域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子。其次，将描述幼虫在杂交带的一部分上扩散的模式。这将有助于确定迁移到杂交种群并随后受到选择的幼虫的地理和遗传起源。四种假设将被检验，以了解特定的环境因素在杂交基因型选择中的作用。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巧合。这些研究将为今后研究中对可能的选择剂进行具体的实验室和实地试验提供基础。其次，分子遗传技术，在以前的国家科学基金会的支持下开发的，将用于确定幼虫种群的起源，以招募到杂交种群。这些信息将为解释在杂交种群中观察到的选择模式以及一旦杂交幼虫从杂交区分散回亲本种群之一后的潜在命运提供基础。

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.