Bigger Is Fitter? Quantitative Genetic Decomposition of Selection Reveals an Adaptive Evolutionary Decline of Body Mass in a Wild Rodent Population
Bigger Is Fitter? Quantitative Genetic Decomposition of Selection Reveals an Adaptive Evolutionary Decline of Body Mass in a Wild Rodent Population
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作者：
Bonnet Timothée;Wandeler Peter;Camenisch Glauco;P. Erik
在自然种群中，数量性状动态似乎并不遵循进化预测：尽管有大量自然选择作用于遗传性状的例子，但当代适应性进化的确凿证据对于野生脊椎动物种群来说仍然很少，而且表型停滞似乎是常态。这种所谓的“停滞悖论”凸显了我们无法预测进化变化，这在快速的人为环境变化的背景下尤其令人担忧。尽管停滞悖论背后的原因存在激烈争论，但缺乏旨在解决问题的全面尝试。在这里，我们将定量遗传框架应用于野生啮齿动物种群的基于个体的长期数据，结果表明，尽管体重和健康之间存在正相关关系，但仍存在体重降低的遗传变化。后者代表了对生存能力选择的适应性反应，有利于幼体成长为相对较小的成年体，即潜在的成年体质量较低，可能会更早地完成发育。这种选择在无雪季节结束时尤其强烈，并且近年来有所加剧，与降雪模式的变化相吻合。重要的是，负面的进化变化和驱动它的选择压力在表型水平上都不明显，它们分别被表型可塑性和体重与健康之间的非因果（即非遗传）正相关所掩盖。因此，在遗传水平上估计选择使我们能够揭示适应性进化的作用，并确定相应的表型选择压力。因此，我们证明自然种群可以对新的选择压力表现出快速和适应性的进化反应，并且明确的（定量）遗传模型能够为我们提供对选择原因和后果的理解，这优于对选择和进化变化的纯粹表型估计。
In natural populations, quantitative trait dynamics often do not appear to follow evolutionary predictions: Despite abundant examples of natural selection acting on heritable traits, conclusive evidence for contemporary adaptive evolution remains rare for wild vertebrate populations, and phenotypic stasis seems to be the norm. This so-called ‘stasis paradox’ highlights our inability to predict evolutionary change, which is especially concerning within the context of rapid anthropogenic environmental change. While the causes underlying the stasis paradox are hotly debated, comprehensive attempts aiming at a resolution are lacking. Here we apply a quantitative genetic framework to individual-based long-term data for a wild rodent population and show that despite a positive association between body mass and fitness, there has been a genetic change towards lower body mass. The latter represents an adaptive response to viability selection favouring juveniles growing up to become relatively small adults, i.e. with a low potential adult mass, which presumably complete their development earlier. This selection is particularly strong towards the end of the snow-free season, and it has intensified in recent years, coinciding which a change in snowfall patterns. Importantly, neither the negative evolutionary change, nor the selective pressures that drive it, are apparent on the phenotypic level, where they are masked by phenotypic plasticity and a non-causal (i.e. non-genetic) positive association between body mass and fitness, respectively. Estimating selection at the genetic level thereby enabled us to uncover adaptive evolution in action, and to identify the corresponding phenotypic selective pressure. We thereby demonstrate that natural populations can show a rapid and adaptive evolutionary response to a novel selective pressure, and that explicitly (quantitative) genetic models are able to provide us with an understanding of the causes and consequences of selection that is superior to purely phenotypic estimates of selection and evolutionary change.
DOI：
10.1016/j.tig.2015.10.001
发表时间：
2016-01
期刊：
Trends in genetics : TIG
影响因子：
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作者：
Ostrander EA;Davis BW;Ostrander GK
通讯作者：
Ostrander GK