Population structure and biogeography of migratory freshwater fishes (Prochilodus : Characiformes) in major South American rivers

摘要

Mitochondrial DNA (mtDNA) sequences were used to infer the phylogenetic relationships of Prochilodus species in the Parana, Amazonas, Orinoco, and Magdalena basins. Sequences of ATPase subunits 6 and 8 (total 840 bp) were obtained for 21 Prochilodus specimens from the four river systems. Using Semaprochilodus as an outgroup, phylogenetic analyses showed that: (i) each river basin contains a monophyletic group of mtDNA lineages; and (ii) the branching order places Magdalena in a basal position with subsequent branching of Orinoco, Amazon and Parana. The mitochondrial control region was sequenced for 26 P. lineatus (from the Parana basin) and six other Prochilodus specimens from the Magdalena, Orinoco and Amazon. All 26 control region haplotypes were unique with sequence divergence ranging from 0.3 to 3.6%. The control region phylogeny is well resolved but phylogenetic structure is not associated with geography. For example, mtDNA haplotypes from the upper Parana (Mogui Guassu) and the upper Bermejo, separated by at least 2600 km, have close genealogical ties. Phylogeographic analyses, including nested clads analysis, suggest high levels of gene flow within this basin. [References: 56]