Comparative cytogenetics of some marsupial species (Didelphimorphia, Didelphidae) from the Amazon basin

Autor: Carlos Eduardo Faresin e Silva, Rodrigo Amaral de Andrade, Érica Martinha Silva de Souza, Eduardo Schmidt Eler, Maria Nazareth da Silva, Eliana Feldberg
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: Comparative Cytogenetics, Vol 11, Iss 4, Pp 703-725 (2017)
Druh dokumentu: article
ISSN: 1993-078X
1993-0771
DOI: 10.3897/compcytogen.v11i4.13962
Popis: We investigated the karyotype of 18 didelphid species captured at 13 localities in the Brazilian Amazon, after conventional staining, C-banding, Ag-NOR and fluorescent in situ hybridization (FISH) using the 18S rDNA probe. Variations were found in the X chromosome, heterochromatin distribution and the 18S rDNA sequence. The main variation observed was in the position of the centromere in the X chromosome of Caluromys philander Linnaeus, 1758 and Marmosa murina Linnaeus, 1758. For both species, the X chromosome showed a geographical segregation in the pattern of variation between eastern and western Brazil, with a possible contact area in the central Amazon. C-banding on the X chromosome revealed two patterns for the species of Marmosops Matschie, 1916, apparently without geographic or specific relationships. The nucleolus organizer region (NOR) of all species was confirmed with the 18S rDNA probe, except on the Y chromosome of Monodelphis touan Shaw, 1800. The distribution of this marker varied only in the genus Marmosa Gray, 1821 [M. murina Thomas, 1905 and M. demerarae Thomas, 1905]. Considering that simple NORs are seen as a plesiomorphic character, we conclude that the species Marmosa spp. and Didelphis marsupialis Linnaeus, 1758 evolved independently to the multiple condition. By increasing the sample, using chromosomal banding, and FISH, we verified that marsupials present intra- and interspecific chromosomal variations, which suggests the occurrence of frequent chromosomal rearrangements in the evolution of this group. This observation contrasts with the chromosomal conservatism expected for didelphids.
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