Comparative karyology in Akodon (Rodentia, Sigmodontinae) from Southeastern Brazil

Karyotypic comparisons among five Akodon species showed that they shared a substantial proportion of their chromosome complements, indicated by distinct homologies between chromosomes, arms, or arm regions despite that this genus is karyotypically rearranged. A comparison with a related outgroup (Bolomys lasiurus) allowed for the recognition of ancestral and derived karyotypic traits as well as for inferring the direction of several chromosome rearrangements. This study indicated that species with lower diploid chromosome number are derived from species with higher diploid number, mainly by 11 fusions and 1 pericentric inversion while the direction of 5 other rearrangements could not be determined (fusions or fissions). UPGMA analyses of karyologic data indicated a topology like (Bolomys lasiurus (Akodon sp. (A. lindberghi (A. montensis (A. aff. cursor, A. cursor))))).