School of Biological Sciences, University of Bristol Woodland Road, Bristol, BS8 1UG, UK.
Ecol Evol. 2014 Jun;4(11):2058-69. doi: 10.1002/ece3.1057. Epub 2014 Apr 24.
Organisms live in heterogeneous environments, so strategies that maximze fitness in such environments will evolve. Variation in traits is important because it is the raw material on which natural selection acts during evolution. Phenotypic variation is usually thought to be due to genetic variation and/or environmentally induced effects. Therefore, genetically identical individuals in a constant environment should have invariant traits. Clearly, genetically identical individuals do differ phenotypically, usually thought to be due to stochastic processes. It is now becoming clear, especially from studies of unicellular species, that phenotypic variance among genetically identical individuals in a constant environment can be genetically controlled and that therefore, in principle, this can be subject to selection. However, there has been little investigation of these phenomena in multicellular species. Here, we have studied the mean lifetime fecundity (thus a trait likely to be relevant to reproductive success), and variance in lifetime fecundity, in recently-wild isolates of the model nematode Caenorhabditis elegans. We found that these genotypes differed in their variance in lifetime fecundity: some had high variance in fecundity, others very low variance. We find that this variance in lifetime fecundity was negatively related to the mean lifetime fecundity of the lines, and that the variance of the lines was positively correlated between environments. We suggest that the variance in lifetime fecundity may be a bet-hedging strategy used by this species.
生物体生活在异质环境中，因此能够最大限度地适应这种环境的策略将会进化。性状的变异很重要，因为它是自然选择在进化过程中作用的原始材料。表型变异通常被认为是由于遗传变异和/或环境诱导效应。因此，在恒定环境中具有相同遗传背景的个体应该具有不变的特征。显然，具有相同遗传背景的个体在表型上确实存在差异，通常被认为是由于随机过程。现在越来越清楚的是，特别是从单细胞物种的研究中可以看出，在恒定环境中具有相同遗传背景的个体之间的表型方差可以受到遗传控制，因此原则上，这可以受到选择的影响。然而，在多细胞物种中，对这些现象的研究很少。在这里，我们研究了模型线虫秀丽隐杆线虫最近野生分离株的平均终生繁殖力（因此是可能与生殖成功相关的特征）及其终生繁殖力的方差。我们发现这些基因型在终生繁殖力的方差上存在差异：一些具有高繁殖力方差，另一些则具有非常低的方差。我们发现，这种终生繁殖力的方差与线的平均终生繁殖力呈负相关，并且线的方差在环境之间呈正相关。我们认为，终生繁殖力的方差可能是该物种使用的一种风险分散策略。
