. Phylogenetic relationships among species of the Neotropical genus Graomys (Rodentia, Cricetidae): contrasting patterns of skull morphometric variation and genetic divergence.

CRISTINA NOEMÍ GARDENAL; JUAN JOSÉ MARTÍNEZ

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 118 p. 648 - 667

0024-4066

Subtle differences of external traits characterize species of rodents in the Neotropical genus Graomys. On theother hand, the species differ markedly in chromosome number. In the present study, we evaluate the possibleevolutionary forces involved in the evolution of the genus by assessing the degree of intra- and interspecificgenetic and morphological variation. A phylogenetic analysis demonstrates the existence of at least three specieswith high levels of genetic distance (10%), which diverged between 1 and 1.5 Mya. Neither Graomys griseoflavus,nor Graomys chacoensis present marked phylogeographical structure. Regarding morphological characters, thesespecies show shape differences in the skull that could be attributable to differences in the local conditions theyinhabit, being more marked in G. griseoflavus than in G. chacoensis. The skull shape of G. chacoensis could haveevolved under genetic drift, whereas evidence reported in the present study indicates that this character could beunder selective pressures in G. griseoflavus. Reconstruction of the ancestral area suggests that G. griseoflavusoriginated in the central Monte desert, whereas G. chacoensis originated in the Chaco ecoregion surrounding theaustral extreme of the Yungas rainforest. Subsequently, both species would have undergone demographic andgeographical expansions almost simultaneously, starting approximately 150 000?175 000 years ago. The complexevolutionary history of the genus could be partly explained by the decoupling of morphological, karyological andmolecular traits.