Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT, Australia.
Australian Museum Research Institute, Australian Museum, Sydney, NSW, Australia.
Mol Biol Evol. 2022 Jan 7;39(1). doi: 10.1093/molbev/msab333.
Chromosome rearrangements can result in the rapid evolution of hybrid incompatibilities. Robertsonian fusions, particularly those with monobrachial homology, can drive reproductive isolation amongst recently diverged taxa. The recent radiation of rock-wallabies (genus Petrogale) is an important model to explore the role of Robertsonian fusions in speciation. Here, we pursue that goal using an extensive sampling of populations and genomes of Petrogale from north-eastern Australia. In contrast to previous assessments using mitochondrial DNA or nuclear microsatellite loci, genomic data are able to separate the most closely related species and to resolve their divergence histories. Both phylogenetic and population genetic analyses indicate introgression between two species that differ by a single Robertsonian fusion. Based on the available data, there is also evidence for introgression between two species which share complex chromosomal rearrangements. However, the remaining results show no consistent signature of introgression amongst species pairs and where evident, indicate generally low introgression overall. X-linked loci have elevated divergence compared with autosomal loci indicating a potential role for genic evolution to produce reproductive isolation in concert with chromosome change. Our results highlight the value of genome scale data in evaluating the role of Robertsonian fusions and structural variation in divergence, speciation, and patterns of molecular evolution.
染色体重排可能导致杂种不亲和性的快速进化。罗伯逊融合，特别是那些具有单臂同源性的融合，会导致最近分化的分类群之间产生生殖隔离。最近的岩石袋鼠（Petrogale 属）辐射是一个探索罗伯逊融合在物种形成中的作用的重要模型。在这里，我们使用来自澳大利亚东北部的大量 Petrogale 种群和基因组样本来实现这一目标。与以前使用线粒体 DNA 或核微卫星位点进行的评估相比，基因组数据能够分离最密切相关的物种，并解决它们的分化历史。系统发育和群体遗传分析都表明，两种在单个罗伯逊融合上存在差异的物种之间存在基因渗入。根据现有数据，还存在两种具有复杂染色体重排的物种之间基因渗入的证据。然而，其余结果没有显示出物种对之间存在一致的基因渗入特征，而且在明显的情况下，总体上表明基因渗入水平较低。与常染色体基因座相比，X 连锁基因座的分化程度较高，这表明基因进化可能与染色体变化一起产生生殖隔离。我们的研究结果强调了基因组规模数据在评估罗伯逊融合和结构变异在分化、物种形成和分子进化模式中的作用的价值。
