Phylogeography and ecological niche modeling refute the unique and sequential origin of chromosome polymorphism in Graomys griseoflavus (Waterhouse 1837) (Rodentia: Cricetidae)

JOSÉ H. URQUIZO; LUIS IGNACIO FERRO; JUAN JOSÉ MARTÍNEZ

Encuentro; The III Meeting of Systematics, Biogeography, and Evolution; 2022

Graomys griseoflavus has a wide geographical distribution in Argentina encompassing several ecoregions across the Arid Diagonal of South America. This species is characterized by its variation in the diploid number (2n) from 33 to 38 caused by three different Robertsonian (Rb) translocations. Two hypotheses exist on the origin and evolution of the Rb rearrangement in this species. One postulates that the variability could have been generated without substantial population size reduction in a parapatric context. The other one proposes a unique and sequential origin of the Rb variants. In this study, we combined phylogeography with ecological niche modeling to disentangle the spatial and demographic history of this species under these hypotheses. We used 99 cyt b sequences covering most of the geographic range of the species (2300 km). The haplotype network revealed a complex pattern of relationships among mtDNA variants, showing signals of multiple population expansions. We detected four genetic clusters of which two have wide geographic ranges: the north cluster (>31°S Lat) and the south cluster (