Genetic diversity of Cebuella Gray, 1866 (Primates, Callitrichinae) from the western Amazonia lowlands and predictions of climate change impacts on its distribution

Brazil, a country with a rich diversity of primates, faces the challenge of preserving these species, since most are at some level of threat of extinction. Among Brazilian primates, the pygmy marmosets (Cebuella niveiventris and C. pygmaea) stand out as the smallest known species of monkey, with a wide distribution in the western Amazon. Faced with the need for quick and well-founded information to guide conservation, recent studies have used analyses of Species Distribution Models (SDMs) for primates. The present study aimed to investigate the genetic diversity in Cebuella, using the mitochondrial gene cytochrome b, and analyze the potential distribution (SDMs) of the two species. The phylogeny showed Cebuella divided into two clades, corresponding to the two species of the genus, corroborating previous findings. Herein, we applied species delimitation tests to the genus Cebuella for the first time, revealing significant divergences. The bPTP method identified six probable species within Cebuella, while the ABGD indicated 15 putative species. Both methods point to a high diversity within the genus. Species suitability modeling suggested that C. niveiventris seems to be more sensitive to seasonal variations in rainfall (BIO15) and the amount of rainfall during the wettest quarter (BIO8), while C. pygmaea appears more impacted by the intensity of the early rainy season (BIO15) and a period of lower rainfall variability throughout the rest of the year. The most pessimistic scenario for the future suggested that the more intense the environmental changes resulting from human activities, the greater the impact on future climates, increasing the probability of population decline.