Charlesworth Brian
Department of Ecology and Evolution, University of Chicago, 1103 E. 57th St., Chicago, IL, 60637.
Evolution. 1990 May;44(3):520-538. doi: 10.1111/j.1558-5646.1990.tb05936.x.
The process of selection on a multivariate set of characters subject to functional constraints is considered from the points of view of both evolutionary optimization theory and quantitative genetics. Special attention is given to life-history characteristics. It is shown that, under suitable conditions (including weak selection), useful approximate formulas for the relations between the functional constraints and the additive genetic variance-covariance matrix can be derived. These can be used to show that the conditions for equilibrium under selection according to the two different approaches are approximately equivalent. Although large negative genetic correlations are to be expected between some pairs of life-history traits in populations at equilibrium under selection, in general some small negative genetic correlations and some positive genetic correlations will also be present. Thus, the observation of a positive genetic correlation between a pair of life-history traits does not necessarily refute the possibility of trade-offs among a multivariate set of traits that contains the pair in question. The relation between the pattern of functional constraints and the genetic correlations is often complex, and little insight into the former can be derived from the latter. The effects of mutations that lower the overall efficiency of resource utilization, thereby creating a positive component to the genetic covariances among life-history traits, are also considered for a specific model. Although such mutations can have a substantial effect on the form of the life history, extreme conditions seem to be needed for them to produce a large effect on the pattern of genetic correlations in a random-mating population. They can, however, cause the appearance of positive correlations following inbreeding, due to the exposure of deleterious recessive or partially recessive mutations. The analysis also suggests that the population means of individual components of a constrained multivariate system may often equilibrate at values that are far from the optima that would be attained if they were selected in isolation from the other members of the system.
从进化优化理论和数量遗传学的角度，对受功能限制的多变量性状集合的选择过程进行了探讨。特别关注了生活史特征。结果表明，在合适的条件下（包括弱选择），可以推导出功能限制与加性遗传方差 - 协方差矩阵之间关系的有用近似公式。这些公式可用于表明，根据两种不同方法进行选择时的平衡条件大致等效。尽管在选择作用下处于平衡状态的种群中，某些生活史性状对之间预期会存在较大的负遗传相关性，但一般来说也会存在一些小的负遗传相关性和一些正遗传相关性。因此，观察到一对生活史性状之间存在正遗传相关性，并不一定反驳在包含该性状对的多变量性状集合中存在权衡的可能性。功能限制模式与遗传相关性之间的关系通常很复杂，从后者很难深入了解前者。对于一个特定模型，还考虑了降低资源利用总体效率从而在生活史性状之间的遗传协方差中产生正分量的突变的影响。尽管此类突变可能对生活史的形式产生重大影响，但似乎需要极端条件才能使其对随机交配种群中的遗传相关性模式产生较大影响。然而，由于有害隐性或部分隐性突变的暴露，它们会导致近亲繁殖后出现正相关性。分析还表明，受约束的多变量系统中各个组成部分的种群均值通常可能在远离如果它们与系统中的其他成员隔离选择时所达到的最优值的水平上达到平衡。
