The Indian subcontinent has an origin geologically different from Eurasia, but many terrestrial animal and plant species on it have congeneric or sister species in other parts of Asia, especially in the Southeast. This faunal and floral similarity between India and Southeast Asia is explained by either of the two biogeographic scenarios, ‘into-India’ or ‘out-of-India’. Phylogenies based on complete mitochondrial genomes and five nuclear genes were undertaken for ricefishes (Adrianichthyidae) to examine which of these two biogeographic scenarios fits better. We found that Oryzias setnai, the only adrianichthyid distributed in and endemic to the Western Ghats, a mountain range running parallel to the western coast of the Indian subcontinent, is sister to all other adrianichthyids from eastern India and Southeast–East Asia. Divergence time estimates and ancestral area reconstructions reveal that this western Indian species diverged in the late Mesozoic during the northward drift of the Indian subcontinent. These findings indicate that adrianichthyids dispersed eastward ‘out-of-India’ after the collision of the Indian subcontinent with Eurasia, and subsequently diversified in Southeast–East Asia. A review of geographic distributions of ‘out-of-India’ taxa reveals that they may have largely fuelled or modified the biodiversity of Eurasia.

印度次大陆的起源在地质上与欧亚大陆不同，但其上的许多陆地动植物物种在亚洲其他地区，特别是东南部，都有同属或姐妹物种。印度和东南亚之间的这种动物和花卉相似性可以通过“进入印度”或“离开印度”这两种生物地理情景中的任何一种来解释。对稻鱼（Adrianichthyidae）进行了基于完整线粒体基因组和五个核基因的系统发育，以检查这两种生物地理情景中哪一种更适合。我们发现Oryzias setnai是唯一分布在西高止山脉并在其特有的地方，与印度次大陆西海岸平行的山脉，是来自印度东部和东南亚的所有其他 Adrianichthyids 的姐妹。分歧时间估计和祖先区域重建表明，这种印度西部物种在中生代晚期印度次大陆向北漂移期间发生分歧。这些发现表明，在印度次大陆与欧亚大陆碰撞后，阿德里安鱼科动物向东“走出印度”分散，随后在东南亚-东亚多样化。对“印度以外”分类群地理分布的回顾表明，它们可能在很大程度上促进或改变了欧亚大陆的生物多样性。