Scorpion Systematics Research Group, Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024-5192, USA.
Graduate School and University Center, City University of New York, 365 5th Avenue, New York, NY, 10016, USA.
Sci Rep. 2019 Mar 5;9(1):3500. doi: 10.1038/s41598-018-33754-8.
Scorpions are an excellent system for understanding biogeographical patterns. Most major scorpion lineages predate modern landforms, making them suitable for testing hypotheses of vicariance and dispersal. The Caribbean islands are endowed with a rich and largely endemic scorpion fauna, the origins of which have not been previously investigated with modern biogeographical methods. Three sets of hypotheses have been proposed to explain present patterns of diversity in the Caribbean: (1) connections via land bridges, (2) vicariance events, and (3) overwater dispersal from continents and among islands. The present study investigates the biogeographical diversification of the New World buthid scorpion subfamily Centruroidinae Kraus, 1955, a clade of seven genera and more than 110 species; infers the ancestral distributions of these scorpions; and tests the relative roles of vicariance and dispersal in the formation of their present distributions. A fossil-calibrated molecular phylogeny was estimated with a Bayesian criterion to infer the dates of diversification events from which ancestral distributions were reconstructed, and the relative likelihood of models of vicariance vs. dispersal, calculated. Although both the timing of diversification and the ancestral distributions were congruent with the GAARlandia land-bridge hypothesis, there was no significant difference between distance-dependent models with or without the land-bridge. Heteroctenus Pocock, 1893, the Caribbean-endemic sister taxon of Centruroides Marx, 1890 provides evidence for a Caribbean ancestor, which subsequently colonized Central America and North America, and eventually re-colonized the Greater Antilles. This 'reverse colonization' event of a continent from an island demonstrates the importance of islands as a potential source of biodiversity.
蝎子是理解生物地理格局的绝佳系统。大多数主要的蝎子谱系都早于现代地貌，因此非常适合测试隔离和扩散假说。加勒比群岛拥有丰富而主要是地方性的蝎子动物群，其起源以前从未用现代生物地理方法进行过研究。已经提出了三组假设来解释加勒比地区目前的多样性模式：(1) 通过陆桥连接，(2) 隔离事件，以及 (3) 从大陆和岛屿之间的水上扩散。本研究调查了新世界 buthid 蝎子亚科 Centruroidinae Kraus, 1955 的生物地理多样化，这是一个由七个属和 110 多种组成的分支；推断这些蝎子的祖先分布；并测试隔离和扩散在形成它们目前分布中的相对作用。使用贝叶斯标准估计了化石校准的分子系统发育，以推断多样化事件的日期，从这些事件中重建了祖先分布，并计算了隔离与扩散模型的相对可能性。尽管多样化的时间和祖先的分布都与 GAARlandia 陆桥假说一致，但没有陆桥的距离相关模型之间没有显着差异。 Heteroctenus Pocock, 1893 是 Centruroides Marx, 1890 的加勒比特有姊妹类群，为加勒比祖先提供了证据，该祖先随后殖民了中美洲和北美洲，并最终重新殖民了大安的列斯群岛。这种从岛屿到大陆的“反向殖民”事件证明了岛屿作为生物多样性潜在来源的重要性。
