Retroposed elements and their flanking regions resolve the evolutionary history of xenarthran mammals (armadillos, anteaters, and sloths)

Armadillos, anteaters, and sloths (Order Xenarthra) comprise 1 of the 4 major clades of placental mammals. Isolated in South America from the other continental landmasses, xenarthrans diverged over a period of about 65 Myr, leaving more than 200 extinct genera and only 31 living species. The presence of both ancestral and highly derived anatomical features has made morphoanatomical analyses of the xenarthran evolutionary history difficult, and previous molecular analyses failed to resolve the relationships within armadillo subfamilies. We investigated the presence/absence patterns of retroposons from ∼7,400 genomic loci, identifying 35 phylogenetically informative elements and an additional 39 informative rare genomic changes (RGCs). DAS-short interspersed elements (SINEs), previously described only in the Dasypus novemcinctus genome, were found in all living armadillo genera, including the previously unsampled Chlamyphorus, but were noticeably absent in sloths. The presence/absence pat...犰狳、食蚁兽与树懒（异关节总目Xenarthra）是胎盘类哺乳动物四大主要演化支之一。它们曾与其他大陆板块隔绝于南美洲，历经约6500万年的演化分化，留下超过200个已灭绝属，现存仅31个物种。异关节类兼具祖先类群与高度特化的解剖学特征，这使得针对其演化历史的形态解剖学分析难度颇高；既往的分子分析也未能厘清犰狳亚科内部的系统发育关系。本研究对约7400个基因组位点的逆转录转座子（retroposons）存在/缺失模式展开分析，共鉴定出35个系统发育信息元件，以及额外39个具有信息价值的稀有基因组变异（rare genomic changes, RGCs）。此前仅在九带犰狳（Dasypus novemcinctus）基因组中报道过的DAS短散在重复序列（short interspersed elements, SINEs），此次在所有现存犰狳属类群中均被发现，包括此前未被采样的披毛犰狳属（Chlamyphorus），但在树懒类群中完全未检测到该序列。其存在/缺失模式……