Species limits and introgression in Pimelodus from the Magdalena-Cauca River basin

Low morphological differentiation among taxa hampers its appropriate identification, basic biological studies, and promotion of any conservation effort. Aiming to clarify the evolution and speciation among members of Pimelodus from the Magdalena-Cauca River basin, this study tested the hypothesis that P. yuma, P. grosskopfii and P. crypticus represent three independently evolving species and explored signals of interspecific hybridization. Likewise, we test the ancient hypothesis that the trans-Andean Pimelodus yuma and P. crypticus belong to the cis-Andean P. blochii species complex. The outcomes based on mitochondrial (cox1) and nuclear [RADseq (Illumina Hi-Seq), microsatellites and rag2] markers combined with coalescence-based and allele-frequency methods, confirm that each studied trans-Andean species represent an independently evolving unit. We used Stacks v.2.52 for de novo SNP genotyping. Contrary to expectations, P. yuma was found as a sister clade of P. blochii, while P. crypti...