Unraveling the Evolutionary History of the Toadlet Rhinella mirandaribeiroi (Gallardo, 1965) (Anura: Bufonidae) in the Cerrado
Anuran, Events, Divergence, Diversification
Amphibian populations exhibit limited dispersal due to their affinity with aquatic environments, small body size, and low mobility. However, landscape elements and climatic events can affect evolutionary processes, influencing species dispersal and their evolutionary history. Few studies have focused on the diversification of endemic toads in the Cerrado, with most research concentrating on factors contributing to high diversity in forest biomes. In the Cerrado, two major hypotheses regarding species diversification are proposed: Neogene changes as the primary geological diversification event and Quaternary climatic fluctuations as a divergence factor for the biome's herpetofauna lineages. To better understand these processes, we studied the species Rhinella mirandaribeiroi, which is widely distributed in open habitats in the Cerrado. We used mitochondrial and nuclear genetic markers to investigate the population structure of the species across its geographic distribution and how these past events affected it. We analyzed 23 samples from 16 localities. We found two populations within R. mirandaribeiroi (South-North Population). We estimated the diversification of R. mirandaribeiroi at 4.84 million years ago, during the Pliocene, while the divergence between the northern and southern populations occurred around 1.739 million years ago, during the Pleistocene. These results are similar to those described for the Cerrado herpetofauna. The southern population showed expansion during the Pleistocene, around 650 to 400 thousand years ago, suggesting that population differentiation may be associated with Quaternary climatic cycles, where populations became isolated and adapted to their habitats. Our results indicate that Neogene and Quaternary changes were relevant to the demographic history of R. mirandaribeiroi.