Awadalla P, Ritland K
Department of Botany, University of Toronto, Ontario, Canada.
Mol Biol Evol. 1997 Oct;14(10):1023-34. doi: 10.1093/oxfordjournals.molbev.a025708.
Mutational variability at microsatellite loci is shaped by both population history and the mating system. In turn, alternate mating systems in flowering plants can resolve aspects of microsatellite loci evolution. Five species of yellow monkeyflowers (Mimulus sect. Simiolis) differing for historical rates of inbreeding were surveyed for variation at six microsatellite loci. High levels of diversity at these loci were found in both outcrossing and selfing taxa. In line with allozyme studies, inbreeders showed more partitioning of diversity among populations, and diversity in selfing taxa was lower than expected from reductions in effective population size due to selfing alone, suggesting the presence of either population bottlenecks or background selection in selfers. Evaluation of the stepwise mutation model (a model of DNA replication slippage) suggests that these loci evolve in a stepwise fashion. Inferred coalescent times of microsatellite alleles indicate that past bottlenecks of population size or colonization events were important in reducing diversity in the inbreeding taxon.
微卫星位点的突变变异性受种群历史和交配系统的共同影响。反过来，开花植物中的交替交配系统可以解析微卫星位点进化的各个方面。对五个因历史近亲繁殖率不同的黄猴面花物种（猴面花属拟猴面花组）的六个微卫星位点的变异情况进行了调查。在异交和自交类群中均发现这些位点具有高水平的多样性。与等位酶研究一致，近亲繁殖者在种群间表现出更多的多样性分配，并且自交类群中的多样性低于仅因自交导致有效种群大小降低所预期的水平，这表明自交者中存在种群瓶颈或背景选择。对逐步突变模型（一种DNA复制滑动模型）的评估表明，这些位点以逐步方式进化。微卫星等位基因的推断合并时间表明，过去的种群大小瓶颈或殖民事件对降低近亲繁殖类群的多样性很重要。
