Sección Genética Evolutiva, Facultad de Ciencias, UdelaR, Iguá 4225, Montevideo 11400, Uruguay.
Departamento de Zoología, Genética y Antropología Física, Facultad de Veterinaria, Campus de Lugo, Universidade de Santiago de Compostela, Avenida Carballo Calero s/n, E-27002 Lugo, Spain.
Genes (Basel). 2020 Jan 17;11(1):109. doi: 10.3390/genes11010109.
, a Neotropical fish with hybridization between highly divergent mitochondrial DNA (mtDNA) lineages, represents an interesting evolutionary model. Previous studies suggested that there might be demographic differences between coastal lagoons and riverine environments, as well as divergent populations that could be reproductively isolated. Here, we investigated the genetic diversity pattern of this taxon in the Southern Neotropical Basin system that includes the La Plata Basin, Patos-Merin lagoon basin and the coastal lagoons draining to the SW Atlantic Ocean, through a population genomics approach using 2b-RAD-sequencing-derived single nucleotide polymorphisms (SNPs). The genomic scan identified selection footprints associated with divergence and suggested local adaptation environmental drivers. Two major genomic clusters latitudinally distributed in the Northern and Southern basins were identified, along with consistent signatures of divergent selection between them. Population structure based on the whole set of loci and on the presumptive neutral vs. adaptive loci showed deep genomic divergence between the two major clusters. Annotation of the most consistent SNPs under divergent selection revealed some interesting candidate genes for further functional studies. Moreover, signals of adaptation to a coastal lagoon environment mediated by purifying selection were found. These new insights provide a better understanding of the complex evolutionary history of in the southernmost basin of the Neotropical region.
一种具有高度分化的线粒体 DNA（mtDNA）谱系杂交的新热带鱼类，代表了一个有趣的进化模型。先前的研究表明，沿海泻湖和河流环境之间可能存在人口统计学差异，以及可能存在生殖隔离的分化种群。在这里，我们通过使用 2b-RAD 测序衍生的单核苷酸多态性（SNP）的种群基因组学方法，研究了包括拉普拉塔盆地、帕托斯-梅林泻湖盆地和西南大西洋沿岸泻湖在内的南新热带盆地系统中这种分类单元的遗传多样性模式。基因组扫描确定了与分化相关的选择足迹，并提出了环境驱动因素的局部适应。在北部和南部盆地沿纬度分布的两个主要基因组簇被识别出来，同时在它们之间存在一致的分歧选择特征。基于整个基因座集和假定的中性与适应性基因座的种群结构显示出两个主要簇之间的深度基因组分化。对分歧选择下最一致的 SNP 的注释揭示了一些有趣的候选基因，用于进一步的功能研究。此外，还发现了通过纯化选择适应沿海泻湖环境的适应信号。这些新的见解为更好地理解新热带地区最南端盆地中 的复杂进化历史提供了帮助。
