Karyologic diversification and phylogenetic relationships of the genusThalpomys (Rodentia, Sigmodontinae)
We describe the karyotype ofThalpomys species, from different Brazilian localities of the Cerrado.Thalpomys cerradensis Herskovitz, 1990 showed 2n=36, FN=34 andT. lasiotis Thomas, 1916 2n=38, FN=38. Comparisons of G-band karyotypes showed evident inter-specific homologies indicating that their chromosome complements could be derived from one another by two presumed rearrangements. Both species showed pericentromeric C-band regions in almost all chromosomes but a comparison with CMA3/DA/DAPI staining indicated that the molecular content of heterochromatic regions was different.T. lasiotis specimens from two different localities differed in the morphology of the X chromosome due to the presence of a short heterochromatic arm. These chromosome types are apparently fixed in each population rather than maintained as a polymorphic variation. Phylogenetic analyses supported the monophyly of the genusThalpomys but was not capable of elucidating its phylogenetic relationship to other Akodontini rodents. These analyses also showed inter-individual variation inT. lasiotis, even within a given population. Phylogenetic analyses placedT. lasiotis specimens with different karyotypes in different monophyletic branches. Molecular and karyologic data confirmed the identity of the genusThalpomys.
Key-wordsRodentia Thalpomys karyotype phylogeny distribution Brazil
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- Alho C. J. R. and Pereira L. A. 1985. Population ecology of a Cerrado rodent community in Central Brazil. Revsta Brasileira de Biologia 45: 597–607.Google Scholar
- Applied Biosystem, Inc. 1994. Sequence Navigator, DNA and Protein Comparison Software. A Division of Perkin-Elmer Corporation, Foster City, CA.Google Scholar
- Armada J. L., Pereira L. A., Filho P. G. S. and Seuánez H. N. 1983. Chromosome number inAkodon reinhardti Langguth, 1975 (Rodentia, Cricetidae). Mammalian Chromosoma Newsletter 24: 176–182.Google Scholar
- Bonvicino C. R., Cerqueira R. and Soares V. A. 1996. Habitat use by small mammals of upper Araguaia river. Revista Brasileira de Biologia 56: 761–767.Google Scholar
- D’Elia G. 2000. Comments on recent advances in understanding sigmodontine phylogeny and evolution. Mastozoologia Neotropical 7: 47–54.Google Scholar
- Kumar S., Tamura K. and Nei M. 2000. MEGA: Molecular evolutionary genetics analysis, version 1.02. Pennsylvania State University, University Park.Google Scholar
- Machado L. B. and Bonvicino C. R. 1999. O cariótipo deThalpomys cerradensis (Rodentia, Sigmodontinae). Genetics and Molecular Biology 22 (Suppl.): 89.Google Scholar
- Mello D. A. and Moojen L. E. 1979. [Notes on one rodent and marsupial collection from some regions of the Cerrado of central Brazil]. Revista Brasileira de Pesquisa Médica e Biológica 12: 287–291. [In Portuguese]Google Scholar
- Sambrook J., Fritsch E. F. and Maniatis T. 1989. Molecular cloning: a laboratory manual. 2nd edition. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, vol. 1: 1–621.Google Scholar
- Swofford D. L. 1993. “PAUP: Phylogenetic Analysis Using Parsimony, version 3.1.1”. Smithsonian Institution Press, Washington.Google Scholar
- Yonenaga-Yassuda Y., Pereira L. A., Armada J. L. and L’Abbate M. 1987. Chromosomal polymorphism inAkodon reinhardti Langguth, 1975 (Rodentia, Cricetidae). Revista Brasileira de Genetica 10: 199–208.Google Scholar