Whether freshwater fish colonize remote islands following tectonic or transoceanic dispersal remains an evolutionary puzzle. Integrating dating of known tectonic events with phylogenomics and current species distribution, we find that killifish species distribution is not explained by species dispersal by tectonic drift only. Investigating the colonization of a nonannual killifish (golden panchax, Pachypanchax playfairii) on the Seychelle islands, we found genetic support for transoceanic dispersal and experimentally discovered an adaptation to complete tolerance to seawater. At the macroevolutionary scale, despite their long-lasting isolation, nonannual golden panchax show stronger genome-wide purifying selection than annual killifishes from continental Africa. However, progressive decline in effective population size over a more recent timescale has probably led to the segregation of slightly deleterious mutations across golden panchax populations, which represents a potential threat for species preservation in the long term.

中文翻译：

---

来自塞舌尔群岛的非一年生鳉鱼的祖先越洋殖民化和最近的种群减少

淡水鱼是否在构造或跨洋扩散后在偏远岛屿上定居仍然是一个进化难题。将已知构造事件的年代学与系统基因组学和当前物种分布相结合，我们发现鳉鱼物种分布不能仅通过构造漂移的物种扩散来解释。调查非一年生鳉鱼（金鳉、Pachypanchax playfairii）的定殖) 在塞舌尔群岛，我们发现了跨洋扩散的遗传支持，并通过实验发现了对海水完全耐受的适应性。在宏观进化尺度上，尽管它们长期隔离，但非一年生的金鱼表现出比来自非洲大陆的一年生鳉鱼更强的全基因组净化选择。然而，在最近的时间尺度上，有效种群规模的逐渐下降可能导致在黄金 panchax 种群中分离出轻微有害的突变，从长远来看，这对物种保护构成了潜在威胁。