Museum of Zoology, Senckenberg Dresden, A. B. Meyer Building, 01109 Dresden, Germany.
Ecology Area, Department of Applied Biology, Miguel Hernández University, 03202 Elche, Spain.
Sci Adv. 2023 Jan 13;9(2):eabq2574. doi: 10.1126/sciadv.abq2574. Epub 2023 Jan 11.
Before humans arrived, giant tortoises occurred on many western Indian Ocean islands. We combined ancient DNA, phylogenetic, ancestral range, and molecular clock analyses with radiocarbon and paleogeographic evidence to decipher their diversity and biogeography. Using a mitogenomic time tree, we propose that the ancestor of the extinct Mascarene tortoises spread from Africa in the Eocene to now-sunken islands northeast of Madagascar. From these islands, the Mascarenes were repeatedly colonized. Another out-of-Africa dispersal (latest Eocene/Oligocene) produced on Madagascar giant, large, and small tortoise species. Two giant and one large species disappeared c. 1000 to 600 years ago, the latter described here as new to science using nuclear and mitochondrial DNA. From Madagascar, the Granitic Seychelles were colonized (Early Pliocene) and from there, repeatedly Aldabra (Late Pleistocene). The Granitic Seychelles populations were eradicated and later reintroduced from Aldabra. Our results underline that integrating ancient DNA data into a multi-evidence framework substantially enhances the knowledge of the past diversity of island faunas.
在人类出现之前，巨型陆龟曾广泛分布于许多西印度洋岛屿上。我们结合古 DNA、系统发育、祖先分布范围和分子钟分析，以及放射性碳测年和古地理证据，来破解它们的多样性和生物地理学。我们利用线粒体基因组的时间树，提出灭绝的马斯克林陆龟的祖先可能在始新世从非洲扩散到马达加斯加东北部现已沉没的岛屿上。这些岛屿是马斯克林群岛的多次起源地。另一次非洲以外的扩散（最晚始新世/渐新世）产生了马达加斯加的巨型、大型和小型陆龟物种。两种巨型和一种大型物种在大约 1000 到 600 年前消失了，其中最后一种在这里被描述为使用核和线粒体 DNA 的新物种。马达加斯加的花岗岩塞舌尔群岛（上新世早期）和从那里，反复出现的阿尔达布拉群岛（更新世晚期）。花岗岩塞舌尔群岛的种群被根除，后来从阿尔达布拉重新引入。我们的研究结果表明，将古 DNA 数据纳入多证据框架可以极大地提高对岛屿动物群过去多样性的认识。
