Data from: Adaptive divergence in the monkey flower Mimulus guttatus is maintained by a chromosomal inversion

Organisms exhibit an incredible diversity of life history strategies as adaptive responses to environmental variation. The establishment of novel life history strategies involves multilocus polymorphisms, which will be challenging to establish in the face of gene flow and recombination. Theory predicts that adaptive allelic combinations may be maintained and spread if they occur in genomic regions of reduced recombination, such as chromosomal inversion polymorphisms, yet empirical support for this prediction is lacking. Here, we use genomic data to investigate the evolution of divergent adaptive ecotypes of the yellow monkey flower Mimulus guttatus. We show that a large chromosomal inversion polymorphism is the major region of divergence between geographically widespread annual and perennial ecotypes. In contrast, ∼40,000 single nucleotide polymorphisms in collinear regions of the genome show no signal of life history, revealing genomic patterns of diversity have been shaped by localized homogenizing gene flow and large-scale Pleistocene range expansion. Our results provide evidence for an inversion capturing and protecting loci involved in local adaptation, while also explaining how adaptive divergence can occur with gene flow.

生物体展现出令人惊叹的生活史策略多样性，以此作为对环境变异的适应性响应。全新生活史策略的建立涉及多基因座多态性，而面对基因流与重组的作用时，这类多态性的建立往往颇具挑战。理论预测，若适应性等位基因组合位于重组率降低的基因组区域（如染色体倒位多态性区域），便可得以维持并扩散，但目前该预测仍缺乏实证支持。本研究借助基因组数据，探究黄色猴面花（Mimulus guttatus）趋异适应生态型的演化过程。研究结果显示，一处大型染色体倒位多态性区域是地理分布广泛的一年生与多年生生态型之间产生分化的核心区域。与之形成鲜明对比的是，基因组共线性区域内的约4万个单核苷酸多态位点未呈现与生活史相关的遗传信号，这表明基因组多样性模式受到局域同质化基因流与大规模更新世范围扩张的共同塑造。本研究结果不仅证实了倒位能够捕获并保护参与局部适应的基因座，同时也解释了在存在基因流的情况下适应性分化何以能够发生。