1 Molecular Genetics and Physiology of Plants, Faculty of Biology and Biotechnology, Ruhr University Bochum , 44801 Bochum , Germany.
2 Cell and Developmental Biology, John Innes Centre , Norwich NR4 7UH , UK.
Philos Trans R Soc Lond B Biol Sci. 2019 Jul 22;374(1777):20180243. doi: 10.1098/rstb.2018.0243. Epub 2019 Jun 3.
It is a plausible hypothesis that parallel adaptation events to the same environmental challenge should result in genetic changes of similar or identical effects, depending on the underlying fitness landscapes. However, systematic testing of this is scarce. Here we examine this hypothesis in two closely related plant species, Arabidopsis halleri and Arabidopsis arenosa, which co-occur at two calamine metalliferous (M) sites harbouring toxic levels of the heavy metals zinc and cadmium. We conduct individual genome resequencing alongside soil elemental analysis for 64 plants from eight populations on M and non-metalliferous (NM) soils, and identify genomic footprints of selection and local adaptation. Selective sweep and environmental association analyses indicate a modest degree of gene as well as functional network convergence, whereby the proximal molecular factors mediating this convergence mostly differ between site pairs and species. Notably, we observe repeated selection on identical single nucleotide polymorphisms in several A. halleri genes at two independently colonized M sites. Our data suggest that species-specific metal handling and other biological features could explain a low degree of convergence between species. The parallel establishment of plant populations on calamine M soils involves convergent evolution, which will probably be more pervasive across sites purposely chosen for maximal similarity in soil composition. This article is part of the theme issue 'Convergent evolution in the genomics era: new insights and directions'.
这是一个合理的假设，即针对相同环境挑战的平行适应事件应该导致相似或相同效果的遗传变化，这取决于潜在的适应度景观。然而，对这一假设的系统测试却很少。在这里，我们在两个密切相关的植物物种中检验了这一假设，即 Arabidopsis halleri 和 Arabidopsis arenosa，它们在两个含有锌和镉等重金属的毒理水平的钙镁矿金属（M）地点共存。我们对来自 M 和非金属（NM）土壤的 8 个种群的 64 株植物进行了个体基因组重测序和土壤元素分析，并确定了选择和局部适应的基因组足迹。选择性清扫和环境关联分析表明，基因和功能网络的趋同程度适中，介导这种趋同的近端分子因素在种间和种内大多不同。值得注意的是，我们观察到在两个独立定殖的 M 地点的几个 A. halleri 基因中，相同的单核苷酸多态性重复受到选择。我们的数据表明，物种特有的金属处理和其他生物学特征可以解释物种间趋同程度较低的原因。植物种群在钙镁矿 M 土壤上的平行建立涉及趋同进化，这在特意选择的土壤成分最大相似性的站点上可能更为普遍。本文是主题为“基因组时代的趋同进化：新的见解和方向”的一部分。
