Holman L, Jacomb F
School of BioSciences, University of Melbourne, Parkville, VIC, Australia.
Research School of Biology, Australian National University, Canberra, ACT, Australia.
J Evol Biol. 2017 Oct;30(10):1898-1909. doi: 10.1111/jeb.13149. Epub 2017 Aug 20.
The capacity of a population to adapt to selection (evolvability) depends on whether the structure of genetic variation permits the evolution of fitter trait combinations. Selection, genetic variance and genetic covariance can change under environmental stress, and males and females are not genetically independent, yet the combined effects of stress and dioecy on evolvability are not well understood. Here, we estimate selection, genetic (co)variance and evolvability in both sexes of Tribolium castaneum flour beetles under stressful and benign conditions, using a half-sib breeding design. Although stress uncovered substantial latent heritability, stress also affected genetic covariance, such that evolvability remained low under stress. Sexual selection on males and natural selection on females favoured a similar phenotype, and there was positive intersex genetic covariance. Consequently, sexual selection on males augmented adaptation in females, and intralocus sexual conflict was weak or absent. This study highlights that increased heritability does not necessarily increase evolvability, suggests that selection can deplete genetic variance for multivariate trait combinations with strong effects on fitness, and tests the recent hypothesis that sexual conflict is weaker in stressful or novel environments.
种群适应选择的能力（可进化性）取决于遗传变异的结构是否允许更适应环境的性状组合进化。在环境压力下，选择、遗传方差和遗传协方差会发生变化，而且雄性和雌性在基因上并非相互独立，但压力和雌雄异株对可进化性的综合影响尚未得到充分理解。在此，我们采用半同胞育种设计，估计了在压力条件和良性条件下赤拟谷盗粉甲虫雌雄两性的选择、遗传（协）方差和可进化性。虽然压力揭示了大量潜在的遗传力，但压力也影响了遗传协方差，因此在压力下可进化性仍然较低。对雄性的性选择和对雌性的自然选择倾向于相似的表型，并且存在正的两性间遗传协方差。因此，对雄性的性选择增强了雌性的适应性，并且基因座内的性冲突较弱或不存在。本研究强调遗传力的增加不一定会提高可进化性，表明选择会消耗对适合度有强烈影响多变量性状组合的遗传方差，并检验了最近提出的在压力或新环境中性冲突较弱的假说。
