Phylogeography reveals complex historical processes and different evolutionarily significant units in Aegla scamosa freshwater crabs

Abstract

Phylogeographic research is able to identify previously unrecognized units of biodiversity. The aeglid Aegla scamosa is a species that inhabits the Desaguadero basin waterbodies in southern South America. Crabs of the family Aeglidae are especially sensitive to changes in their environment since they have restricted distributions. The aims of our study were to characterize the phylogeography of A. scamosa across its distributional range in Argentina and to identify evolutionarily signifcant units from these phylogeographic data. We used mitochondrial DNA, nuclear intron, and microsatellite DNA markers to study the genetic diversity, population structure, and phylogeography of the species. Our results indicate that A. scamosa populations are genetically structured in the analyzed sub-basins and that the species comprises at least two independent evolutionarily units: one corresponding to the “North” clade and another coinciding with the “South” clade. We also found a presumptive discrepancy between the information provided by nuclear and mitochondrial markers, that tell diferent evolutionary stories. Our results highlight the importance of carrying out this kind of study in freshwater fauna, since they may be hiding diferent evolutionarily signifcant units as in the case of A. scamosa. The evolutionary complexity of this species should not be ignored in future conservation studies.