Käär P, Jokela J, Helle T, Kojola I
Department of Biology, University of Turku, Finland.
Proc Biol Sci. 1996 Nov 22;263(1376):1475-80. doi: 10.1098/rspb.1996.0215.
Because natural selection acts simultaneously on several correlated traits, can be under both direct and correlative selection simultaneously. Correlative selection may either weaken or magnify the association between a trait and fitness. Direct effect of a single trait on fitness can be assessed by removing the effects of correlative selection with multivariate techniques. We studied the phenotypic selection on demographic life-history traits in three pre-industrial human populations, which experienced different mortality environments. We used path-analysis to estimate direct and correlative selection on different traits in females and males. Our results indicate substantial differences among the sexes in the force of phenotypic selection on key life-history traits. For females, the most important component of reproductive success was the age at first reproduction. Most important component of fitness for males was the quality of mate. In addition, our analysis revealed considerable among-population variation in the selection on life-history traits. These differences are in accord with the historical notes of among-population variation in the lifestyle and harshness of the environment, suggesting that among-population variation in life-history traits may have been a response to the environmental variation.
由于自然选择同时作用于几个相关性状，所以一个性状可能同时受到直接选择和相关选择。相关选择可能会削弱或放大一个性状与适合度之间的关联。单一性状对适合度的直接影响可以通过多变量技术去除相关选择的影响来评估。我们研究了三个工业化前的人类群体中人口统计学上的生活史性状的表型选择，这些群体经历了不同的死亡环境。我们使用路径分析来估计对女性和男性不同性状的直接选择和相关选择。我们的结果表明，在关键生活史性状的表型选择强度上，两性之间存在显著差异。对于女性来说，生殖成功的最重要组成部分是首次生育的年龄。男性适合度的最重要组成部分是配偶质量。此外，我们的分析揭示了生活史性状选择在群体间存在相当大的差异。这些差异与群体间生活方式和环境严酷程度的历史记录一致，表明生活史性状的群体间差异可能是对环境差异的一种反应。
