Population Structure and the Evolution of Inbreeding Depression

植物表现出惊人的交配系统多样性。具有混合交配系统的植物物种(例如，自交和异交)为研究自然选择如何塑造交配系统提供了一个特殊的机会。这项拟议的研究将使用常见的一年生凤仙花来检验近亲繁殖衰退是随着种群近亲交配的历史而增加还是减少。利用电泳法，研究人员将分析近亲交配的来源和几个自然种群的遗传结构。这些信息将与竞争实验得出的每个种群的近亲繁殖衰退和遗传负荷水平进行比较。这应该揭示出遗传负荷是由于漂移和突变而增加，还是在近亲交配发生时通过选择而被清除。这些信息将有助于阐明稀有和受威胁物种的小种群面临的遗传危险，并可能有助于指导农业项目中的人工选择和植物育种。

Plants display a remarkable diversity of mating systems. Plant species that have mixed mating systems (e.g., both self- fertilize and outcross) provide a special opportunity for studying how natural selection molds the mating system. Some controversy surrounds this issue because different theoretical models make different predictions concerning which factors are important. The proposed research will use the common annual, Impatiens capensis, to examine whether inbreeding depression increases or decreases with a history of inbreeding in a population. Using electrophoresis, the investigator will analyze the sources of inbreeding and genetic structure in several natural populations. This information will be compared to levels of inbreeding depression and genetic load in each population derived from competition experiments. This should reveal whether the genetic load increases due to drift and mutation, or is purged via selection when inbreeding occurs. The results of this research should help determine which possible genetic effects steer mating system evolution. In addition, it should identify the sources and consequences of inbreeding in natural populations. This information will help illuminate the genetic hazards faced by the small populations of rare and threatened species and may help guide artificial selection and plant breeding in agricultural programs.