Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA.
Biology Department, University of Nevada Reno, Reno, NV, 89557, USA.
Sci Rep. 2020 Jan 28;10(1):1373. doi: 10.1038/s41598-020-58224-y.
Quaternary paleontological and archaeological evidence often is crucial for uncovering the historical mechanisms shaping modern diversity and distributions. We take an interdisciplinary approach using multiple lines of evidence to understand how past human activity has shaped long-term animal diversity in an island system. Islands afford unique opportunities for such studies given their robust fossil and archaeological records. Herein, we examine the only non-volant terrestrial mammal endemic to the Bahamian Archipelago, the hutia Geocapromys ingrahami. This capromyine rodent once inhabited many islands but is now restricted to several small cays. Radiocarbon dated fossils indicate that hutias were present on the Great Bahama Bank islands before humans arrived at AD 800-1000; all dates from other islands post-date human arrival. Using ancient DNA from a subset of these fossils, along with modern representatives of Bahamian hutia and related taxa, we develop a fossil-calibrated phylogeny. We found little genetic divergence among individuals from within either the northern or southern Bahamas but discovered a relatively deep North-South divergence (750 ka). This result, combined with radiocarbon dating and archaeological evidence, reveals a pre-human biogeographic divergence, and an unexpected human role in shaping Bahamian hutia diversity and biogeography across islands.
古生物学和考古学的证据常常是揭示塑造现代多样性和分布格局的历史机制的关键。我们采用跨学科的方法，利用多种证据来理解过去人类活动如何塑造了岛屿系统中动物的长期多样性。岛屿为这类研究提供了独特的机会，因为它们拥有丰富的化石和考古记录。本文研究了巴哈马群岛特有的唯一一种非飞行陆地哺乳动物——筑巢豪猪（Geocapromys ingrahami）。这种豪猪曾广泛分布于多个岛屿，但现在仅限于几个小珊瑚礁。放射性碳测年化石表明，豪猪在公元 800-1000 年左右人类到达之前就已经存在于大巴哈马浅滩群岛上；其他岛屿的所有年代都晚于人类的到来。我们利用这些化石中的一部分古 DNA，以及巴哈马豪猪和相关分类群的现代代表，构建了一个化石校准的系统发育树。我们发现，来自巴哈马北部或南部的个体之间遗传差异很小，但发现了一个相对较深的南北分歧（约 75 万年）。这一结果与放射性碳测年和考古证据相结合，揭示了人类出现前的生物地理分歧，以及人类在塑造巴哈马豪猪多样性和岛屿生物地理学方面的意外作用。
