Shaw R G, Byers D L, Shaw F H
Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, Minnesota 55108, USA.
Genetics. 1998 Dec;150(4):1649-61. doi: 10.1093/genetics/150.4.1649.
The standard approaches to estimation of quantitative genetic parameters and prediction of response to selection on quantitative traits are based on theory derived for populations undergoing random mating. Many studies demonstrate, however, that mating systems in natural populations often involve inbreeding in various degrees (i.e. , self matings and matings between relatives). Here we apply theory developed for estimating quantitative genetic parameters for partially inbreeding populations to a population of Nemophila menziesii recently obtained from nature and experimentally inbred. Two measures of overall plant size and two of floral size expressed highly significant inbreeding depression. Of three dominance components of phenotypic variance that are defined under partial inbreeding, one was found to contribute significantly to phenotypic variance in flower size and flowering time, while the remaining two components contributed only negligibly to variation in each of the five traits considered. Computer simulations investigating selection response under the more complete genetic model for populations undergoing mixed mating indicate that, for parameter values estimated in this study, selection response can be substantially slowed relative to predictions for a random mating population. Moreover, inbreeding depression alone does not generally account for the reduction in selection response.
估计数量遗传参数以及预测数量性状选择响应的标准方法是基于为随机交配群体推导出来的理论。然而，许多研究表明，自然群体中的交配系统常常涉及不同程度的近亲繁殖（即自交以及近亲之间的交配）。在此，我们将为部分近亲繁殖群体估计数量遗传参数而开发的理论应用于最近从自然界获得并经实验近亲繁殖的弯叶紫堇种群。两种衡量植株整体大小的指标以及两种花大小的指标均表现出高度显著的近亲繁殖衰退。在部分近亲繁殖情况下定义的表型方差的三个显性成分中，发现其中一个对花大小和开花时间的表型方差有显著贡献，而其余两个成分对所考虑的五个性状中每个性状的变异贡献极小。针对混合交配群体在更完整遗传模型下研究选择响应的计算机模拟表明，对于本研究中估计的参数值，相对于随机交配群体的预测，选择响应可能会大幅减缓。此外，仅近亲繁殖衰退通常并不能解释选择响应的降低。
