Journal of Genetics

, Volume 91, Issue 3, pp 265–277 | Cite as

Genetic and morphological variability in South American rodent Oecomys (Sigmodontinae, Rodentia): evidence for a complex of species

  • C. C. ROSA
  • R. V. ROSSI
  • M. I. C. SAMPAIO
  • P. J. S. AMARAL


The rodent genus Oecomys (Sigmodontinae) comprises ~16 species that inhabit tropical and subtropical forests in Central America and South America. In this study specimens of Oecomys paricola Thomas, 1904 from Belém and Marajó island, northern Brazil, were investigated using cytogenetic, molecular and morphological analyses. Three karyotypes were found, two from Belém (2n = 68, fundamental number (FN) = 72 and 2n = 70, FN = 76) and a third from Marajó island (2n = 70, FN = 72). No molecular or morphological differences were found between the individuals with differing cytotypes from Belém, but differences were evident between the individuals from Belém and Marajó island. Specimens from Belém city region may represent two cryptic species because two different karyotypes are present in the absence of significant differences in morphology and molecular characteristics. The Marajó island and Belém populations may represent distinct species that have been separated for some time, and are in the process of morphological and molecular differentiation as a consequence of reproductive isolation at the geographic and chromosomal levels. Thus, the results suggest that O. paricola may be a complex of species.


cytogenetics chromosome speciation cryptic species rodent Oecomys paricola 



C. C. Rosa is a recipient of FAPESPA Mastership Scholarship in Neurosciences and Cellular Biology; J. C. Pieczarka, M. I. C. Sampaio, C. Y. Nagamachi are CNPq Researchers; P. J. S. Amaral is a recipient of FAPESPA Doctorship Scholarship in Genetic and Molecular Biology at Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil. T. Flores is a recipient of CAPES Mastership Scholarship in Zoology at Laboratório de Genética e Biologia Molecular, Universidade Federal do Pará, Campus Universitário de Bragança, Pará, Brazil.

The authors thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and the Fundação de Amparo à Pesquisa do Estado do Pará (FAPESPA) for financial support, and the Instituto Brasileiro de Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) for authorizing sample collection.


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Copyright information

© Indian Academy of Sciences 2012

Authors and Affiliations

  • C. C. ROSA
    • 1
    • 2
    • 1
  • R. V. ROSSI
    • 3
  • M. I. C. SAMPAIO
    • 2
    • 1
  • P. J. S. AMARAL
    • 1
    • 1
  1. 1.Laboratório de Citogenética, Instituto de Ciências BiológicasUniversidade Federal do ParáBelémBrazil
  2. 2.Laboratório de Genética e Biologia MolecularUniversidade Federal do Pará, Campus Universitário de BragançaParáBrazil
  3. 3.Departamento de Biologia e Zoologia, Instituto de BiociênciasUniversidade Federal do Mato GrossoMato GrossoBrazil

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