Basin-scale distribution and haplotype partitioning in different genetic lineages of the Neotropical migratory fish Salminus brasiliensis

Abstract

Four valid species are currently recognized in the Neotropical migratory genus Salminus: Salminus brasiliensis, Salminus franciscanus, Salminus hilarii and Salminus affinis. However, molecular evidence strongly suggested that two different species might be contained under the taxonomic denomination Salminus brasiliensis. Therefore, the geographical distribution of each entity was evaluated in order to understand their contribution to the different stocks of major river networks in South America. Major river networks of the La Plata River basin were explored to characterize the geographical distribution of the two genetic lineages. To characterize further the genetic partitioning within each lineage of S. brasiliensis, a haplotype analysis was conducted. The 5′ region of the mitochondrial COI gene was used as the molecular marker. In total, 45 fish samples of S. brasiliensis from 19 sites in Argentina, Brazil and Paraguay were sequenced. Additional COI sequences of S. brasiliensis, S. franciscanus and S. hilarii were gathered from public databases. All samples of S. brasiliensis comprised two different mitochondrial lineages. Accordingly, phylogenetic tree topologies segregated the complete set of sequences into two disparate clusters. One of these clusters was far closer phylogenetically to S. hilarii than to other S. brasiliensis. While one of the genetic lineages of S. brasiliensis seemed mostly restricted to the upper Paraná River, the other showed a widespread distribution along major river networks of the basin. Fifteen unique haplotypes were identified and collapsed. Salminus hilarii and S. franciscanus have private haplotypes. In S. brasiliensis, each mitochondrial lineage also hosts a set of unshared haplotypes. The sympatry of two different putative species within S. brasiliensis together with their unshared haplotypes present a difficult situation for management and conservation that calls for timely solutions.