Osborne Owen G, Chapman Mark A, Nevado Bruno, Filatov Dmitry A
Department of Plant Sciences, University of Oxford, Oxford, United Kingdom Department of Life Sciences, Imperial College London - Silwood Park Campus, Berkshire, United Kingdom
Department of Plant Sciences, University of Oxford, Oxford, United Kingdom Department of Life Sciences, Imperial College London - Silwood Park Campus, Berkshire, United Kingdom Centre for Biological Sciences, Faculty of Natural & Environmental Sciences, University of Southampton, Southampton, United Kingdom.
Genome Biol Evol. 2016 Apr 13;8(4):1038-47. doi: 10.1093/gbe/evw053.
The role of hybridization between diversifying species has been the focus of a huge amount of recent evolutionary research. While gene flow can prevent speciation or initiate species collapse, it can also generate new hybrid species. Similarly, while adaptive divergence can be wiped out by gene flow, new adaptive variation can be introduced via introgression. The relative frequency of these outcomes, and indeed the frequency of hybridization and introgression in general are largely unknown. One group of closely-related species with several documented cases of hybridization is the Mediterranean ragwort (genus: Senecio) species-complex. Examples of both polyploid and homoploid hybrid speciation are known in the clade, although their evolutionary relationships and the general frequency of introgressive hybridization among them remain unknown. Using a whole genome gene-space dataset comprising eight Senecio species we fully resolve the phylogeny of these species for the first time despite phylogenetic incongruence across the genome. Using a D-statistic approach, we demonstrate previously unknown cases of introgressive hybridization between multiple pairs of taxa across the species tree. This is an important step in establishing these species as a study system for diversification with gene flow, and suggests that introgressive hybridization may be a widespread and important process in plant evolution.
分化物种间杂交的作用一直是近期大量进化研究的焦点。虽然基因流可以阻止物种形成或引发物种崩溃，但它也能产生新的杂交物种。同样，虽然适应性分化可能会被基因流消除，但新的适应性变异可以通过渐渗作用引入。这些结果的相对频率，以及杂交和渐渗作用的总体频率在很大程度上是未知的。地中海千里光（属：千里光属）物种复合体是一组有多个杂交记录案例的近缘物种。尽管该分支中多倍体和同倍体杂交物种形成的例子是已知的，但其进化关系以及它们之间渐渗杂交的总体频率仍然未知。我们使用包含八个千里光属物种的全基因组基因空间数据集，首次完全解析了这些物种的系统发育，尽管整个基因组存在系统发育不一致的情况。使用D统计方法，我们展示了物种树中多对分类群之间以前未知的渐渗杂交案例。这是将这些物种确立为基因流驱动多样化研究系统的重要一步，并表明渐渗杂交可能是植物进化中一个广泛且重要的过程。
