Phylogenetic identity and population structure of the dwarf caimans Paleosuchus spp. in the Orinoco basin of Colombia and Venezuela: filling gaps

Abstract

Dwarf caiman species of the genus Paleosuchus (Paleosuchus palpebrosus and Paleosuchus trigonatus) are old, widespread crocodilian lineages with populations affected by habitat modification. For both species, phylogeographical studies revealing crucial information have already been performed, but for important ecoregions, such as the Orinoco, knowledge is lacking. In this study, the phylogenetic identity of individuals of Paleosuchus spp. from the Orinoco basin of Colombia and Venezuela was evaluated. The genetic structure of the two species of Paleosuchus was also determined and their genetic diversity quantified. The results show a marked genetic structuring in both species, also indicating that the populations of P. trigonatus and P. palpebrosus of the Orinoco basin are well differentiated from those of other hydrographic basins. For Colombia, it was possible to infer that there are two independent management units for both species (Orinoco and Amazonas) and that the populations of the Orinoco basin present high genetic and haplotypic diversity. In Venezuela, only one management unit was identified for each species. This finding, together with the results of previous studies, show that, in total, there are at least five management units for P. palpebrosus and six for P. trigonatus, throughout their distribution areas. It is necessary to take this information into account when establishing conservation strategies for these species, although it is stressed that the geographical sampling must be improved in future phylogeographical studies, because information gaps persist at the geographical level.