Evolutionary Ecology and Systematics Laboratory, Department of Molecular Biology and Biotechnology, University of Peradeniya, Peradeniya, 20400, Sri Lanka.
Postgraduate Institute of Science, University of Peradeniya, Peradeniya, 20400, Sri Lanka.
Sci Rep. 2023 Oct 31;13(1):18724. doi: 10.1038/s41598-023-45377-9.
Sri Lanka's biota is derived largely from Southeast Asian lineages which immigrated via India following its early-Eocene contact with Laurasia. The island is now separated from southeastern India by the 30 km wide Palk Strait which, during sea-level low-stands, was bridged by the 140 km-wide Palk Isthmus. Consequently, biotic ingress and egress were mediated largely by the climate of the isthmus. Because of their dependence on perennial aquatic habitats, freshwater fish are useful models for biogeographic studies. Here we investigate the timing and dynamics of the colonization of-and diversification on-Sri Lanka by a group of four closely-related genera of cyprinid fishes (Puntius sensu lato). We construct a molecular phylogeny based on two mitochondrial and two nuclear gene markers, conduct divergence timing analyses and ancestral-range estimations to infer historical biogeography, and use haplotype networks to discern phylogeographic patterns. The origin of Puntius s.l. is dated to ~ 20 Ma. The source of diversification of Puntius s.l. is Sri Lanka-Peninsular India. Species confined to perhumid rainforests show strong phylogeographic structure, while habitat generalists show little or no such structure. Ancestral range estimations for Plesiopuntius bimaculatus and Puntius dorsalis support an 'Out of Sri Lanka' scenario. Sri Lankan Puntius s.l. derive from multiple migrations across the Palk Isthmus between the early Miocene and the late Pleistocene. Species dependent on an aseasonal climate survived aridification in rainforest refugia in the island's perhumid southwest and went on to recolonize the island and even southern India when pluvial conditions resumed. Our results support an historical extinction of Sri Lanka's montane aquatic fauna, followed by a recent partial recolonization of the highlands, showing also that headwater stream capture facilitated dispersal across basin boundaries.
斯里兰卡的生物群主要源自东南亚血统，这些血统通过印度迁徙而来，在早始新世与劳亚古陆接触之后。该岛现在与东南印度由 30 公里宽的保克海峡隔开，在海平面低位时期，这条海峡由 140 公里宽的保克地峡连接。因此，生物的进出主要受地峡气候的影响。由于它们依赖于常年水生栖息地，淡水鱼类是生物地理研究的有用模型。在这里，我们调查了一组四个密切相关的鲤鱼属鱼类（广义的 Puntius）在斯里兰卡的殖民和多样化的时间和动态。我们构建了一个基于两个线粒体和两个核基因标记的分子系统发育，进行了分歧时间分析和祖先范围估计，以推断历史生物地理学，并使用单倍型网络来辨别系统地理学模式。Puntius s.l. 的起源可以追溯到 2000 万年前。Puntius s.l. 的多样化起源是斯里兰卡-印度半岛。局限于湿润雨林的物种表现出强烈的系统地理学结构，而栖息地广布的物种则表现出很少或没有这种结构。Plesiopuntius bimaculatus 和 Puntius dorsalis 的祖先范围估计支持“走出斯里兰卡”的情景。斯里兰卡的 Puntius s.l. 源自早中新世至更新世晚期多次通过保克地峡的迁徙。依赖季节性气候的物种在岛屿湿润的西南雨林避难所中幸存下来，当湿润条件恢复时，它们继续重新殖民该岛，甚至重新殖民印度南部。我们的结果支持斯里兰卡山地水生动物群的历史灭绝，随后是最近高地的部分重新殖民，也表明源头溪流捕获促进了流域边界的扩散。
