Accelerated evolution of morph-biased genes in pea aphids.
Accelerated evolution of morph-biased genes in pea aphids.
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DOI：
10.1093/molbev/msu149
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发表时间：
2014-08
影响因子：
10.7
通讯作者：
Swapna R. Purandare;Ryan D. Bickel;J. Jaquiéry;C. Rispe;J. Brisson
中科院分区：
文献类型：
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作者：
Swapna R. Purandare;Ryan D. Bickel;J. Jaquiéry;C. Rispe;J. Brisson
表型可塑性，即由于环境因素而从相同基因型产生替代表型（或变体），导致某些基因以变体偏好的方式表达。从理论上讲，这些偏向形态的基因经历了宽松的选择，其结果是在这些基因上积累了轻微有害的突变。随着时间的推移，预计这将导致物种之间这些基因的蛋白质差异增加，以及物种内放松纯化选择的特征。在这里，我们测试这些理论的期望，在豌豆蚜虫，一个物种，产生多个变种，通过多态性的形态偏向基因。我们发现，形态偏向基因表现出更快的进化速度（dN/dS）相对于无偏见的基因和分歧一般会随着形态偏见的增加而增加。此外，表达偏向于罕见变体（有性雌性和雄性）的基因显示出比在更常见的变体（无性雌性）中表达的基因更快的进化速率，这表明基因在变体中表达的时间与其进化速率相关。最后，我们表明，基因表达的罕见变种的经验减少净化选择相对于无偏见的基因，这表明这是一个放松的净化选择，有助于他们更快的进化速度。我们的研究结果提供了一个重要的经验看看表型可塑性对基因进化的影响。
Phenotypic plasticity, the production of alternative phenotypes (or morphs) from the same genotype due to environmental factors, results in some genes being expressed in a morph-biased manner. Theoretically, these morph-biased genes experience relaxed selection, the consequence of which is the buildup of slightly deleterious mutations at these genes. Over time, this is expected to result in increased protein divergence at these genes between species and a signature of relaxed purifying selection within species. Here we test these theoretical expectations using morph-biased genes in the pea aphid, a species that produces multiple morphs via polyphenism. We find that morph-biased genes exhibit faster rates of evolution (in terms of dN/dS) relative to unbiased genes and that divergence generally increases with increasing morph bias. Further, genes with expression biased toward rarer morphs (sexual females and males) show faster rates of evolution than genes expressed in the more common morph (asexual females), demonstrating that the amount of time a gene spends being expressed in a morph is associated with its rate of evolution. And finally, we show that genes expressed in the rarer morphs experience decreased purifying selection relative to unbiased genes, suggesting that it is a relaxation of purifying selection that contributes to their faster rates of evolution. Our results provide an important empirical look at the impact of phenotypic plasticity on gene evolution.