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Genetics and Molecular Biology
On-line version ISSN 1678-4685
SILVA, Maria José de J.; PATTON, James L. and YONENAGA-YASSUDA, Yatiyo. Phylogenetic relationships and karyotype evolution in the sigmodontine rodent Akodon (2n = 10 and 2n = 16) from Brazil. Genet. Mol. Biol. [online]. 2006, vol.29, n.3, pp. 469-474. ISSN 1678-4685. http://dx.doi.org/10.1590/S1415-47572006000300012.
Comparison of G-bands from 2n = 10 and 2n = 16 karyotypes of Akodon revealed tandem fusions, pericentric inversions and Robertsonian rearrangement in autosomes and addition/deletion of constitutive heterochromatin in sex chromosomes. Cytochrome-b sequences indicate that the 2n = 10 karyotype is a new species and show it to be a sister taxon of the 2n = 14, 2n = 15 and 2n = 16 karyotypes. Indeed, this group shows a particular evolutionary situation in which a unique taxonomic unit based on morphological data can be detected, but, karyologically, it can be separated into two groups (2n = 14-15-16 and 2n = 10). Cytochrome-b sequences show a finer resolution, indicating that these four karyotypes represent three molecular entities (2n = 14-15, 2n = 16 and 2n = 10) that may be derived from a common ancestor with a 2n = 16 karyotype.
Keywords : Akodon; cytochrome-b; G-bands; karyotypical evolution; phylogeny.