Universidad Nacional de Colombia - Sede Medellín, Facultad de Ciencias, Escuela de Biociencias, Laboratorio de Biología Molecular y Celular, Carrera 65 No 59A - 110 Bloque 19A Laboratorio 310, Medellín 050034, Colombia; Grupo de Investigación Biociencias, Facultad de Ciencias de la Salud, Institución Universitaria Colegio Mayor de Antioquia, Cra 78 #65-46, Medellín, Antioquia, Colombia.
Universidad Nacional de Colombia - Sede Medellín, Facultad de Ciencias, Escuela de Biociencias, Laboratorio de Biología Molecular y Celular, Carrera 65 No 59A - 110 Bloque 19A Laboratorio 310, Medellín 050034, Colombia.
Mol Phylogenet Evol. 2022 Aug;173:107517. doi: 10.1016/j.ympev.2022.107517. Epub 2022 May 14.
Low morphological differentiation among taxa hampers their appropriate identification, basic biological studies and promotion of any conservation effort. Aiming to provide the first insight into the evolution and speciation among north-western South American members of Pimelodus, this study tested the hypothesis that Pimelodus yuma, Pimelodus grosskopfii and Pimelodus crypticus represent three independently evolving species and explored signals of interspecific hybridisation. The outcomes based on mitochondrial (cox1) and nuclear (RADseq, microsatellites and rag2) markers combined with coalescence-based and allele-frequency methods confirmed that each studied species represents an independently evolving unit. Contrary to expectations, P. yuma was found as a sister clade of P. blochii, while P. crypticus (formerly confused with P. blochii) was phylogenetically closer to P. grosskopfii. We also found strong evidence of ancient introgression (0.66-3.32 mya) between the non-sibling species P. yuma and P. grosskopfii, breaking the absence of interbreeding and the independent evolutionary trajectory among north-western South American Pimelodus during their diversification history, a pre-requisite to define species limits. However, there were non-significant values of current gene flow between them, supporting the hypothesis of full isolation.
低形态分化阻碍了分类单元的准确鉴定、基础生物学研究以及任何保护工作的开展。本研究旨在深入了解南美西北部的 Pimelodus 鱼类的进化和物种形成，为此检验了以下假设：即 Pimelodus yuma、Pimelodus grosskopfii 和 Pimelodus crypticus 代表三个独立进化的物种，并探讨了种间杂交的信号。基于线粒体（cox1）和核（RADseq、微卫星和 rag2）标记物的综合分析，以及基于合并和等位基因频率的方法，结果均证实了每个研究物种均代表一个独立进化的单元。出乎意料的是，P. yuma 被发现是 P. blochii 的姐妹群，而 P. crypticus（以前与 P. blochii 混淆）在系统发育上与 P. grosskopfii 更为接近。我们还发现了强有力的证据表明，非亲缘物种 P. yuma 和 P. grosskopfii 之间存在古老的基因渗透（0.66-3.32 百万年前），打破了它们在分化历史中没有杂交和独立进化轨迹的假设，这是定义物种界限的前提条件。然而，它们之间当前基因流的非显著值支持完全隔离的假设。
