Complex constraints on allometry revealed by artificial selection on the wing of Drosophila melanogaster
Complex constraints on allometry revealed by artificial selection on the wing of Drosophila melanogaster
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DOI：
10.1073/pnas.1505357112
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发表时间：
2015-10-27
影响因子：
11.1
通讯作者：
Pelabon, Christophe
中科院分区：
文献类型：
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作者：
Bolstad, Geir H.;Cassara, Jason A.;Pelabon, Christophe
精确的指数尺度是表型变异的一个基本方面。这些异速生长幂律在不同的分类群中通常是不变的，并且长期以来一直被假设为反映发育限制。在这里，我们测试这一假设，通过调查果蝇翅膀形状的异速生长比例关系的进化潜力，这是几乎不变的111个物种分开至少50万年的进化。在黑腹果蝇种群的人工选择只有26代，我们能够驱动的异速生长斜率的外部范围中发现的111个采样的物种。当选择被暂停时，这种反应迅速消失。只有一小部分的这种逆转可以用连锁不平衡的打破来解释，而且对机翼形状的直接选择也不可能解释这种逆转，因为通过异速生长截距的选择产生的更加发散的机翼形状并没有逆转。我们假设，相反，逆转是由内部选择所产生的多效性链接到未知的性状。我们的研究结果还表明，所观察到的选择反应的异速生长斜率是由于一个组件在幼虫发育后期表达，并在早期发展的变化没有响应选择。总之，这些结果是一致的多效性的限制，在解释显着的进化稳定性异速生长的作用。
Precise exponential scaling with size is a fundamental aspect of phenotypic variation. These allometric power laws are often invariant across taxa and have long been hypothesized to reflect developmental constraints. Here we test this hypothesis by investigating the evolutionary potential of an allometric scaling relationship in drosophilid wing shape that is nearly invariant across 111 species separated by at least 50 million years of evolution. In only 26 generations of artificial selection in a population of Drosophila melanogaster, we were able to drive the allometric slope to the outer range of those found among the 111 sampled species. This response was rapidly lost when selection was suspended. Only a small proportion of this reversal could be explained by breakup of linkage disequilibrium, and direct selection on wing shape is also unlikely to explain the reversal, because the more divergent wing shapes produced by selection on the allometric intercept did not revert. We hypothesize that the reversal was instead caused by internal selection arising from pleiotropic links to unknown traits. Our results also suggest that the observed selection response in the allometric slope was due to a component expressed late in larval development and that variation in earlier development did not respond to selection. Together, these results are consistent with a role for pleiotropic constraints in explaining the remarkable evolutionary stability of allometric scaling.