Incipient speciation by divergent adaptation and antagonistic epistasis in yeast
Incipient speciation by divergent adaptation and antagonistic epistasis in yeast
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DOI：
10.1038/nature05856
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发表时间：
2007-05-31
期刊：
影响因子：
64.8
通讯作者：
Anderson, James B.
中科院分区：
文献类型：
--
作者：
Dettman, Jeremy R.;Sirjusingh, Caroline;Anderson, James B.
建立促进生殖隔离和物种形成进化的条件一直是进化生物学的目标（1-3）。在生态物种形成中，种群间的生殖隔离是分化选择和由此产生的环境特异性适应的副产品（4-6）。生殖隔离的主要遗传模型预测，杂种劣势是由相互作用位点上不相容等位基因之间的拮抗上位引起的（1,7）。分化适应与通过遗传不相容而产生的生殖隔离之间的根本联系已被预测（1,4,5），但尚未通过实验直接证明。在这里，我们通过在实验群体中进化酿酒酵母物种形成的初始阶段，经验检验了物种形成理论的关键预测。在复制群体适应了两种不同的环境后，我们一致地观察到杂种合子后分离的两种形式的进化：有丝分裂繁殖率降低和减数分裂繁殖效率降低。正如生态物种形成理论所预测的那样，这种分化选择导致了比平行选择更大的生殖隔离。我们的实验系统允许对生态隔离和遗传隔离的相对重要性进行对照比较，并且我们证明杂交劣势可以是生态和/或遗传的基础。总的来说，我们的研究结果表明，对不同环境的适应通过拮抗上位性促进了生殖隔离的进化，为自然界中物种形成和适应性辐射的合理共同途径提供了证据。
Establishing the conditions that promote the evolution of reproductive isolation and speciation has long been a goal in evolutionary biology(1-3). In ecological speciation, reproductive isolation between populations evolves as a by-product of divergent selection and the resulting environment-specific adaptations(4-6). The leading genetic model of reproductive isolation predicts that hybrid inferiority is caused by antagonistic epistasis between incompatible alleles at interacting loci(1,7). The fundamental link between divergent adaptation and reproductive isolation through genetic incompatibilities has been predicted(1,4,5), but has not been directly demonstrated experimentally. Here we empirically tested key predictions of speciation theory by evolving the initial stages of speciation in experimental populations of the yeast Saccharomyces cerevisiae. After replicate populations adapted to two divergent environments, we consistently observed the evolution of two forms of postzygotic isolation in hybrids: reduced rate of mitotic reproduction and reduced efficiency of meiotic reproduction. This divergent selection resulted in greater reproductive isolation than parallel selection, as predicted by the ecological speciation theory. Our experimental system allowed controlled comparison of the relative importance of ecological and genetic isolation, and we demonstrated that hybrid inferiority can be ecological and/or genetic in basis. Overall, our results show that adaptation to divergent environments promotes the evolution of reproductive isolation through antagonistic epistasis, providing evidence of a plausible common avenue to speciation and adaptive radiation in nature.