Evolutionary biogeography of Cnesterodontini (Teleostei: Poeciliidae): area relationships and priority ranking for conservation

Distributional, phylogenetic, molecular, and paleontological data may be integrated to discover biogeographic patterns exhibited by the organisms. Cladistic biogeography uses information on the phylogenetic relationships between taxa and their geographic distribution to infer a sequence of area fragmentation. Brooks Parsimony Analysis (BPA) was performed based on the phylogenetic proposals for Cnesterodontini to hypothesize on the historical relationships among nine areas previously recognized by endemism of freshwater fish from South America. Additionally, we investigated the conservation scenario for cnesterodontines based on biogeographic, phylogenetic, and extinction criteria to establish a priority ranking for the analyzed areas. We found that the area relationships for Cnesterodontini are strongly linked to the historical patterns of evolution of the hydrographic basins, revealing well-defined scenarios of the formation of hydrological barriers between coastal river basins (i.e., Atlantic Slope) and mainly drainages running into the La Plata River system (i.e., Inland Slope). Dispersal events through headwater capture and sea-level changes explain the congruences evidenced among other fish lineages that exhibit similar diversification patterns in the Central Brazil drainages and in drainages on the Atlantic coast of South America. The ranking of priority areas for conservation established for Cnesterodontini indicates that greater attention should be directed to the regions located in the Central Coastal and Upper Parana areas, mainly in the Atlantic Forest, which represents one of the most threatened biodiversity hotspots on the planet with serious threats to freshwater biodiversity.

Automated summary

Distributional, phylogenetic, molecular, and paleontological data were used to reveal biogeographic patterns. Cladistic biogeography inferred area fragmentation based on phylogenetic relationships and geographical distribution of freshwater fish from South America. Brooks Parsimony Analysis (BPA) was performed on Cnesterodontini to analyze historical relationships among nine areas. The results showed strong linkages between area relationships, historical evolution of hydrographic basins, and formation of hydrological barriers.