Simultaneous radiation of bird and mammal lice following the K-Pg boundary

The diversification of parasite groups often occurs at the same time as the diversification of their hosts. However, most studies demonstrating this concordance only examine single host-parasite groups. Multiple diverse lineages of ectoparasitic lice occur across both birds and mammals. Here we describe the evolutionary history of lice based on analyses of 1,107 single copy orthologous genes from sequenced genomes of 46 species of lice. We identify three major diverse groups of lice: one exclusively on mammals, one almost exclusively on birds, and one on both birds and mammals. Each of these groups radiated just after the Cretaceous-Paleogene (K-Pg) boundary, the time of the mass extinction event of the dinosaurs and rapid diversification of most of the modern lineages of birds and mammals.寄生物类群的分化往往与其宿主的分化同步发生。然而，多数验证这一协同一致性的研究仅聚焦于单一宿主-寄生物类群。鸟类与哺乳类动物中均存在多样的外寄生虱（ectoparasitic lice）演化支系。本研究基于对46种虱子基因组测序得到的1107个单拷贝直系同源基因（single copy orthologous genes）的分析，阐明了虱子的演化历史。研究鉴定出三大主要的虱子演化类群：其一仅专性寄生于哺乳类动物，其二几乎仅寄生于鸟类，其三则可同时寄生于鸟类与哺乳类动物。上述三类类群均在白垩纪-古近纪（K-Pg）界线之后发生辐射演化——该时期恰逢恐龙大规模灭绝事件发生，同时也是绝大多数现生鸟类与哺乳类现代演化支系快速分化的关键阶段。