Data from: Population structure of a widespread bat (Tadarida brasiliensis) in an island system

Dispersal is a driving factor in the creation and maintenance of biodiversity, yet little is known about the effects of habitat variation and geography on dispersal and population connectivity in most mammalian groups. Bats of the family Molossidae are fast-flying mammals thought to have potentially high dispersal ability, and recent studies have indicated gene flow across hundreds of kilometers in continental North American populations of the Brazilian free-tailed bat, Tadarida brasiliensis. We examined the population genetics, phylogeography, and morphology of this species in Florida and across islands of The Bahamas, which are part of an island archipelago in the West Indies. Previous studies indicate that bats in the family Phyllostomidae, which are possibly less mobile than members of the family Molossidae, exhibit population structuring across The Bahamas. We hypothesized that T. brasiliensis would show high population connectivity throughout the islands and that T. brasiliensis would show higher connectivity than two species of phyllostomid bats that have been previously examined in The Bahamas. Contrary to our predictions, T. brasiliensis shows high population structure between two groups of islands in The Bahamas, similar to the structure exhibited by one species of phyllostomid bat. Phylogenetic and morphological analyses suggest that this structure may be the result of ancient divergence between two populations of T. brasiliensis that subsequently came into contact in The Bahamas. Our findings additionally suggest that there may be cryptic species within T. brasiliensis in The Bahamas and the West Indies more broadly.扩散是生物多样性产生与维持的关键驱动因素，然而针对绝大多数哺乳动物类群，生境变异与地理特征对其扩散能力及种群连通性的影响，目前仍缺乏深入认知。犬吻蝠科（Molossidae）蝙蝠为高速飞行的哺乳类，被认为拥有极强的扩散潜力；已有研究显示，北美大陆种群的巴西游离尾蝠（Tadarida brasiliensis）存在跨数百公里的基因交流。本研究针对分布于佛罗里达州及巴哈马群岛（西印度群岛群岛的组成部分）的该物种开展种群遗传学（population genetics）、系统地理学（phylogeography）与形态学分析。既往研究表明，移动能力可能弱于犬吻蝠科的叶口蝠科（Phyllostomidae）蝙蝠，在巴哈马群岛范围内存在显著的种群结构分化。据此我们提出两项假说：一是巴西游离尾蝠在巴哈马群岛全域将表现出较高的种群连通性；二是该物种的种群连通性水平将高于此前在巴哈马群岛被研究的两种叶口蝠科蝙蝠。然而研究结果与预测相悖：巴西游离尾蝠在巴哈马群岛的两组岛群间呈现显著的种群结构分化，这与某一种叶口蝠科蝙蝠的种群结构特征相似。系统发育与形态学分析表明，这种种群结构或源于两支巴西游离尾蝠种群的古老分化，后续二者在巴哈马群岛区域发生二次接触。本研究结果还提示，巴哈马群岛乃至更广范围的西印度群岛区域内，巴西游离尾蝠类群中可能存在隐存种（cryptic species）。