Gromko Mark H
Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio, 43403.
Evolution. 1995 Aug;49(4):685-693. doi: 10.1111/j.1558-5646.1995.tb02305.x.
Given a set of loci that contribute additive genetic variation for a trait being selected, the pleiotropic effects of these loci on a second trait may vary. I simulated selection on genetic systems having different combinations of pleiotropic effects to investigate the variability of correlated responses to selection. The simulation shows that there are many possible combinations of pleiotropic effects that are characterized by the same value of the genetic correlation; the genetic correlation does not uniquely determine a set of pleiotropic effects. Furthermore, for a given value of the genetic correlation, differences in pleiotropic effects have a substantial impact on the variation in correlated responses. Some combinations of pleiotropic effects constrain correlated response to a narrow range of possible values; others allow a wide range, including some correlated responses in a direction opposite the sign of the genetic correlation. The genetic correlation is not a reliable predictor of pleiotropic constraint. Whereas it has been previously established that genetic correlations are not necessarily constraints, the alternative is also true: correlated response can be strictly constrained despite a genetic correlation of zero. Given the frequency of correlated responses in a direction opposite to the one predicted by the genetic correlation, it follows that correlated response is not a reliable predictor of genetic correlation in the base population.
对于一组对正在选择的某一性状贡献加性遗传变异的基因座，这些基因座对第二个性状的多效性影响可能会有所不同。我对具有不同多效性影响组合的遗传系统进行了选择模拟，以研究选择相关反应的变异性。模拟结果表明，存在许多具有相同遗传相关值特征的多效性影响组合；遗传相关性并不能唯一确定一组多效性影响。此外，对于给定的遗传相关值，多效性影响的差异对相关反应的变异有重大影响。一些多效性影响组合将相关反应限制在狭窄的可能值范围内；其他组合则允许更广泛的范围，包括一些与遗传相关符号相反方向的相关反应。遗传相关性并不是多效性限制的可靠预测指标。虽然之前已经确定遗传相关性不一定是限制因素，但反之亦然：尽管遗传相关性为零，相关反应也可能受到严格限制。鉴于出现与遗传相关性预测方向相反的相关反应的频率，因此相关反应并不是基础群体中遗传相关性的可靠预测指标。
