Centro de Biodiversidad y Descubrimiento de Drogas, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), P. O. Box 0843-01103, Panamá, República de Panamá.
Department of Biotechnology, Acharya Nagarjuna University, Guntur, India.
Sci Rep. 2019 Dec 11;9(1):18828. doi: 10.1038/s41598-019-55336-y.
Spatial isolation is one of the main drivers of allopatric speciation, but the extent to which spatially-segregated populations accumulate genetic differences relevant to speciation is not always clear. We used data from ultraconserved elements (UCEs) and whole mitochondrial genomes (i.e., mitogenomes) to explore genetic variation among allopatric populations of the weakly electric fish Sternopygus dariensis across the Isthmus of Panama. We found strong genetic divergence between eastern and western populations of S. dariensis. Over 77% of the UCE loci examined were differentially fixed between populations, and these loci appear to be distributed across the species' genome. Population divergence occurred within the last 1.1 million years, perhaps due to global glaciation oscillations during the Pleistocene. Our results are consistent with a pattern of genetic differentiation under strict geographic isolation, and suggest the presence of incipient allopatric species within S. dariensis. Genetic divergence in S. dariensis likely occurred in situ, long after the closure of the Isthmus of Panama. Our study highlights the contribution of spatial isolation and vicariance to promoting rapid diversification in Neotropical freshwater fishes. The study of spatially-segregated populations within the Isthmus of Panama could reveal how genetic differences accumulate as allopatric speciation proceeds.
地理隔离是异域物种形成的主要驱动因素之一，但在何种程度上，地理隔离的种群积累了与物种形成相关的遗传差异尚不清楚。我们利用超保守元件 (UCEs) 和整个线粒体基因组 (即线粒体基因组) 的数据，探索了巴拿马地峡弱电鱼 Sternopygus dariensis 的异域种群之间的遗传变异。我们发现 S. dariensis 的东部和西部种群之间存在强烈的遗传分化。在研究的 UCE 基因座中，超过 77%的基因座在种群间存在差异固定，这些基因座似乎分布在物种基因组的不同位置。种群分化发生在过去的 110 万年左右，可能是由于更新世期间的全球冰川波动。我们的研究结果与严格地理隔离下的遗传分化模式一致，并表明 S. dariensis 中存在初期的异域物种。S. dariensis 的遗传分化可能是原地发生的，早在巴拿马地峡关闭之后很久。我们的研究强调了地理隔离和隔离在促进新热带淡水鱼类快速多样化方面的贡献。对巴拿马地峡内的地理隔离种群的研究可以揭示随着异域物种形成的进行，遗传差异是如何积累的。
