研究使用了有丝分裂基因组时间树，研究人员认为已经灭绝的马斯卡林龟的祖先，在始新世从非洲传播到现在马达加斯加东北部沉没的岛屿上。从这些岛屿开始，马斯卡林龟持续更新换代。非洲之外的另一次(始新世/渐新世晚期)扩散给马达加斯加带来了巨型、大型和小型的龟种。两个巨型物种和一种大型物种在大约1000到600年前消失了，后者在这里被描述为有细胞核和线粒体DNA的科学新发现。
从马达加斯加开始，由花岗岩组成的塞舌尔成为龟类的开拓地(上新世早期)，在晚更新世，阿尔达布拉群岛成为主要开拓地。生活在花岗岩组成的塞舌尔的种群灭绝后，阿尔达布拉群岛的龟类物质重新加入。研究结果强调，将古代DNA数据整合到一个多证据框架中，极大地提高了人们对岛屿动物群过去多样性的认识。
据悉，在人类到来之前，许多西印度洋岛屿上就出现了巨型陆龟。研究组将古代DNA、系统发育、祖先分布和分子钟分析与放射性碳和古地理证据相结合，以破译它们的多样性和生物地理学。
附：英文原文
Title: Ancient DNA elucidates the lost world of western Indian Ocean giant tortoises and reveals a new extinct species from Madagascar
Author: Christian Kehlmaier, Eva Graciá, Jason R. Ali, Patrick D. Campbell, Sandra D. Chapman, V. Deepak, Flora Ihlow, Nour-Eddine Jalil, Laure Pierre-Huyet, Karen E. Samonds, Miguel Vences, Uwe Fritz
Issue&Volume: 2023-01-11
Abstract: 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.
DOI: abq2574
Source: https://www.science.org/doi/10.1126/sciadv.abq2574