Data from: Model-based analysis supports interglacial refugia over long-dispersal events in the diversification of two South American cactus species

Pilosocereus machrisii and P. aurisetus are cactus species within the P.
aurisetus complex, a group of eight cacti that are restricted to rocky
habitats within the Neotropical savannas of eastern South America.
Previous studies have suggested that diversification within this complex
was driven by distributional fragmentation, isolation leading to
allopatric differentiation, and secondary contact among divergent
lineages. These events have been associated with Quaternary climatic
cycles, leading to the hypothesis that the xerophytic vegetation patches
which presently harbor these populations operate as refugia during the
current interglacial. However, owing to limitations of the standard
phylogeographic approaches used in these studies, this hypothesis was not
explicitly tested. Here we use Approximate Bayesian Computation to refine
the previous inferences and test the role of different events in the
diversification of two species within P. aurisetus group. We used
molecular data from chloroplast DNA and simple sequence repeats loci of P.
machrisii and P. aurisetus, the two species with broadest distribution in
the complex, in order to test if the diversification in each species was
driven mostly by vicariance or by long-dispersal events. We found that
both species were affected primarily by vicariance, with a refuge model as
the most likely scenario for P. aurisetus and a soft vicariance scenario
most probable for P. machrisii. These results emphasize the importance of
distributional fragmentation in these species, and add support to the
hypothesis of long-term isolation in interglacial refugia previously
proposed for the P. aurisetus species complex diversification.