Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
Mol Phylogenet Evol. 2019 Apr;133:166-175. doi: 10.1016/j.ympev.2019.01.009. Epub 2019 Jan 11.
The Socotra Archipelago in the Arabian Sea is considered one of the most geo-politically isolated landforms on earth and a center of endemism. The archipelago is located at the western edge of the Indian Ocean and comprises four islands: Socotra, Darsa, Samha, and Abd al Kuri. Here we provide an integrative study on Haemodracon geckos, the sole genus of geckos strictly endemic to the archipelago. The sympatric distribution of Haemodracon riebeckii and H. trachyrhinus on Socotra Island provides a unique opportunity to explore evolutionary relationships and speciation patterns, examining the interplay between possible sympatric and allopatric scenarios. We used molecular data for phylogenetic inference, species delimitation analyses, and to infer the diversification timeframe. Multivariate statistics were used to analyze morphological data. Ecological comparisons were explored for macro-niches using species distribution models and observations were used for micro-habitat use. Haemodracon species exhibit great levels of intraspecific genetic diversity. Our calibration estimates revealed that Haemodracon diverged from its closest relative, the mainland genus Asaccus, in the Eocene, before the detachment of the archipelago. The two Haemodracon species diversified in situ on Socotra Island during the Middle Miocene, after the archipelago's isolation, into the two reciprocally monophyletic recognized species. Their divergence is associated mostly with remarkable body size differences and micro-habitat segregation, with low levels of climatic and body shape divergences within their sympatric distributions. These results display how ecological, sympatric speciation, and allopatric speciation followed by secondary contact, may both have varying roles at different evolutionary phases.
索科特拉群岛位于阿拉伯海，被认为是地球上地理上最为孤立的地貌之一，也是特有物种的中心。该群岛位于印度洋的西部边缘，由四个岛屿组成：索科特拉岛、代尔萨岛、萨姆哈岛和阿布达尔库里岛。在这里，我们对严格特有于该群岛的壁虎属 Haemodracon 进行了综合研究。Haemodracon riebeckii 和 H. trachyrhinus 在索科特拉岛上的同域分布为探索进化关系和物种形成模式提供了独特的机会，检验了可能的同域和异域情景之间的相互作用。我们使用分子数据进行系统发育推断、物种划分分析，并推断多样化时间范围。多元统计用于分析形态数据。使用物种分布模型对宏观生态位进行生态比较，并利用观察结果对微观生境使用进行分析。Haemodracon 物种表现出高度的种内遗传多样性。我们的校准估计表明，Haemodracon 与最接近的亲缘关系，大陆属 Asaccus，在始新世分化，早于群岛的分离。这两个 Haemodracon 物种在中新世期间在索科特拉岛上就地多样化，在群岛隔离之后，分化成两个相互单系的公认物种。它们的分化主要与显著的体型差异和微生境隔离有关，在它们的同域分布中，气候和体型的差异水平较低。这些结果展示了生态、同域物种形成和异域物种形成以及随后的二次接触，如何在不同的进化阶段发挥不同的作用。
