Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA.
Proc Biol Sci. 2010 Oct 7;277(1696):2945-50. doi: 10.1098/rspb.2010.0568. Epub 2010 May 12.
Natural selection operates throughout the life cycle of an organism. Correlative studies typically fail to consider the effects of viability selection prior to trait expression. A 3-year field experiment on the wildflower Mimulus guttatus demonstrates that this unmeasured component of selection can be very strong. As in previous studies, we find that fecundity is positively related to flower size. However, survival to flowering is much lower in large-flowered genotypes than in small-flowered genotypes. Aggregating viability and fecundity, lifetime fitness through female function generally favoured smaller flowered genotypes. This result differs from the great majority of field studies, which suggest strong positive selection on flower size. It has important cautionary implications for studies of natural and sexual selection on adult characters generally, in both plants and animals.
自然选择贯穿生物体的整个生命周期。相关研究通常未能在性状表达之前考虑生存力选择的影响。对野生植物双色金光菊的一项为期 3 年的野外实验表明，这种未被测量的选择成分可能非常强大。与之前的研究一样，我们发现繁殖力与花的大小呈正相关。然而，在大型花基因型中，生存到开花的比例比小型花基因型低得多。通过雌性功能将生存力和繁殖力进行聚合，雌性的终生适合度通常有利于小花型基因型。这一结果与绝大多数野外研究不同，后者表明对花的大小有强烈的正向选择。这对植物和动物中关于成体特征的自然选择和性选择的研究具有重要的警示意义。
