Genetic and morphological variability in South American rodent Oecomys (Sigmodontinae, Rodentia): evidence for a complex
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RESEARCH ARTICLE
Genetic and morphological variability in South American rodent Oecomys (Sigmodontinae, Rodentia): evidence for a complex of species C. C. ROSA1 , T. FLORES2 , J. C. PIECZARKA1 , R. V. ROSSI3 , M. I. C. SAMPAIO2 , J. D. RISSINO1 , P. J. S. AMARAL1 and C. Y. NAGAMACHI1 ∗ 1
Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66.075-900, Brazil 2 Laboratório de Genética e Biologia Molecular, Universidade Federal do Pará, Campus Universitário de Bragança, Pará 68.370-000, Brazil 3 Departamento de Biologia e Zoologia, Instituto de Biociências, Universidade Federal do Mato Grosso 79.070-900, Brazil
Abstract 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. [Rosa C. C., Flores T., Pieczarka J. C., Rossi R. V., Sampaio M. I. C., Rissino J. D., Amaral P. J. S. and Nagamachi C. Y. 2012 Genetic and morphological variability in South American rodent Oecomys (Sigmodontinae, Rodentia): evidence for a complex of species. J. Genet. 91, 265–277]
Introduction Rodents are important members of most faunal communities, as they are cosmopolitan and native to most terrestrial areas. Wide variation in their morphology, and diversity of their habitats, climatic tolerance and food sources make them the most numerous and evolutionarily successful among the orders of mammals (Emmons and Feer 1997). The subfamily Sigmodontinae, which includes most of the species of South American rodents, occurs only in Americas. It includes 386 species in 81 genera and nine tribes: Abrotrichini, Akodontini, Ichthyomyini, Oryzomyini, Phyllotini, Reithrodontini, Sigmodontini, Thomasomyini and Wiedomyini (Reig 1980; Smith and Patton 1999; Musser and Carleton 2005; Weksler et al. 2006; D’Elía et al. 2007). The tribe Oryzomyini comprises 28 genera (Weksler et al. 2006) and includes the genus Oecomys, which was ∗ For correspondence. E-mail: cleusanagamachi@
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