Data from: Genomic evidence for the parallel evolution of coastal forms in the Senecio lautus complex

Instances of parallel ecotypic divergence where adaptation to similar conditions repeatedly cause similar phenotypic changes in closely related organisms are useful for studying the role of ecological selection in speciation. Here we used a combination of traditional and next generation genotyping techniques to test for the parallel divergence of plants from the Senecio lautus complex, a phenotypically variable groundsel that has adapted to disparate environments in the South Pacific. Phylogenetic analysis of a broad selection of Senecio species showed that members of the S. lautus complex form a distinct lineage that has diversified recently in Australasia. An inspection of thousands of polymorphisms in the genome of 27 natural populations from the S. lautus complex in Australia revealed a signal of strong genetic structure independent of habitat and phenotype. Additionally, genetic differentiation between populations was correlated with the geographical distance separating them, and the genetic diversity of populations strongly depended on geographical location. Importantly, coastal forms appeared in several independent phylogenetic clades, a pattern that is consistent with the parallel evolution of these forms. Analyses of the patterns of genomic differentiation between populations further revealed that adjacent populations displayed greater genomic heterogeneity than allopatric populations and are differentiated according to variation in soil composition. These results are consistent with a process of parallel ecotypic divergence in face of gene flow.

适应相似环境后可在近缘生物中反复引发相似表型改变的平行生态型分化实例，对于探究生态选择在物种形成过程中的作用具有重要研究价值。本研究结合传统基因分型技术与下一代基因分型（next generation genotyping）技术，对来自千里光（Senecio lautus）复合群的植物开展平行分化检测。该复合群为一类表型多样的千里光属植物，已适应南太平洋地区的多种迥异生境。对广泛选取的千里光属物种开展系统发育分析后发现，S. lautus复合群成员构成一个独特的演化支系，近期在澳大拉西亚地区发生了分化。对澳大利亚境内该复合群的27个自然种群的基因组数千处多态位点进行检测后，结果显示存在显著的遗传结构，且该结构与生境及表型均无关联。此外，种群间的遗传分化与彼此间的地理距离呈正相关，种群的遗传多样性则强烈依赖于其地理分布位置。尤为关键的是，海岸型种群在多个独立的系统发育分支中均有出现，这一模式与这些类群的平行演化结果相符。对种群间基因组分化模式的进一步分析还显示，邻域种群相较于异域种群展现出更高的基因组异质性，且种群分化与土壤成分的差异密切相关。上述结果与存在基因流情况下发生平行生态型分化的过程相一致。