Laboratorio de Biología de la Conservación, CECOAL (Centro de Ecología Aplicada del Litoral) CONICET, Corrientes, Argentina.
Fuller Evolutionary Biology Program, Cornell Laboratory of Ornithology, Cornell University, Ithaca, New York, USA.
Mol Ecol. 2020 Jun;29(12):2137-2149. doi: 10.1111/mec.15384. Epub 2020 Mar 4.
The riverine barrier hypothesis proposes that large rivers represent geographical barriers to gene flow for terrestrial organisms, leading to population differentiation and ultimately allopatric speciation. Here we assess for the first time if the subtropical Paraná-Paraguay River system in the Del Plata basin, second in size among South American drainages, acts as a barrier to gene flow for birds. We analysed the degree of mitochondrial and nuclear genomic differentiation in seven species with known subspecies divided by the Paraná-Paraguay River axis. Only one species showed genetic differentiation concordant with the current river channel, but another five species have an east/west genetic split broadly coincident with the Paraná River's dynamic palaeochannel, suggesting this fluvial axis has had a past role in shaping present-day genetic structure. Moreover, dating analyses show that these splits have been asynchronous, with species responding differently to the riverine barrier. Comparisons informed by the geological history of the Paraná River and its influence on the ecological and climatic differences among ecoregions in the study area further bolster the finding that responses to this geographical barrier have been species-specific.
河流屏障假说提出，对于陆生生物来说，大型河流是基因流动的地理屏障，导致种群分化，并最终导致异地物种形成。在这里，我们首次评估了南美洲第二大水系——拉普拉塔河流域的亚热带巴拉那-巴拉圭河系统是否对鸟类的基因流动起到了屏障作用。我们分析了七个已知亚种的物种的线粒体和核基因组分化程度，这些物种沿巴拉那-巴拉圭河轴线分布。只有一个物种的遗传分化与当前的河道一致，但另外五个物种的遗传分化呈东西向分裂，与巴拉那河的动态古河道大致吻合，这表明这条河流轴线过去在塑造现代遗传结构方面发挥了作用。此外，年代分析表明，这些分裂是不同步的，物种对河流屏障的反应不同。根据巴拉那河的地质历史及其对研究区域内生态和气候差异的影响进行的比较，进一步支持了这样一种观点，即对这种地理屏障的反应是物种特异性的。
