Biogeographic patterns in the chromosomal distribution of a satellite DNA in the banded tetra Astyanax fasciatus (Teleos
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ORIGINAL ARTICLE
Biogeographic patterns in the chromosomal distribution of a satellite DNA in the banded tetra Astyanax fasciatus (Teleostei: Characiformes) Karine Frehner Kavalco & Rubens Pazza & Karina de Oliveira Brandão & Lurdes Foresti de Almeida-Toledo Received: 26 January 2011 / Accepted: 7 June 2012 / Published online: 3 July 2012 # Gesellschaft für Biologische Systematik 2012
Abstract The As-51 satellite DNA is a transposon-like sequence formerly described for arthropods and physically identifiable by fluorescent in situ hybridization. In the present work, we describe the occurrence of this sequence, as well the C-banding and karyotype composition, in populations of the group Astyanax fasciatus from Mogi-Guaçu (Araras-SP), Paranapanema (Angatuba and Pilar do Sul-SP), Ribeira de Iguape (Sete Barras-SP) and Tietê (Indaiatuba and Salesópolis-SP) river basins. The specimens from Sete Barras (10 M + 20SM + 12ST + 6A) and Araras (8 M + 22SM + 12ST + 6A) have 2n048 chromosomes. The samples from Angatuba, Pilar do Sul and Indaiatuba presented 2n046 chromosomes (12 M + 20SM + 10ST + 4A). The individuals collected in Salesópolis showed three cytotypes, bearing 2n046 (12 M + 20SM + 10ST + 4A), 2n048 (8 M + 22SM + 12ST + 6A) and 2n0 50 (8 M + 16SM + 14ST + 12A). C-banding revealed large heterochromatic blocks at terminal chromosomal regions in all populations and/or cytotypes. All analyzed populations have conspicuous blocks carrying the As-51 satellite DNA, although the number of chromosomes bearing this repetitive sequence was variable among them. Such differences were K. F. Kavalco (*) : R. Pazza Laboratório de Genética Ecológica e Evolutiva, Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Viçosa, Campus de Rio Paranaíba. Rodovia BR 354 - km 310, PO Box 22, ZIP 38810-000 Rio Paranaíba, MG, Brazil e-mail: [email protected] K. de Oliveira Brandão Université Libre de Bruxelles, Campus de la Plaine, Boulevard du Triomphe, ZIP B-1050 Brussels, Belgium L. F. de Almeida-Toledo Universidade de São Paulo. Instituto de Biociências, Rua do Matão, 277 - Edifício André Dreyfus, Cidade Universitária, ZIP 05508090 São Paulo, SP, Brazil
not related to the diploid number of individuals, but rather to a biogeographic pattern. Aspects of the karyotype evolution and distribution of this sequence in distinct populations are discussed. Keywords Astyanax fasciatus . Molecular cytogenetics . Karyotypic evolution . satDNA As-51
Introduction Interesting biogeographic features are observed in the freshwater fish fauna along the Brazilian crystalline shield and coastal drainages. The diversity patterns reported suggest that cladogenic events between both structures are ongoing over long stretches of time, and are, in a sense, repetitive, giving rise to similar sister-group phylogenetic patterns, which occurred at different stages in time (Ribeiro 2006). The rivers encompassing the coastal drainage flow exclusively through the Brazilian territory, ranging from the mouth of the São Francisco River up to Itajaí River (Paiva 1
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