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A multi-approach analysis of the genetic diversity in populations of Astyanax aff. bimaculatus Linnaeus, 1758 (Teleostei: Characidae) from Northeastern Brazil

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Author(s): Vanessa de Carvalho Cayres Pamponet | Paulo Luiz Souza Carneiro | Paulo Roberto Antunes de Mello Affonso | Viviam Souto Miranda | Juvenal Cordeiro Silva Júnior | Claudine Gonçalves de Oliveira | Fernanda Amato Gaiotto

Journal: Neotropical Ichthyology
ISSN 1679-6225

Volume: 6;
Issue: 4;
Start page: 621;
Date: 2008;
Original page

Keywords: Morphometry | Cytogenetics | RAPD | Population structure | Contas River

ABSTRACT
Few reports are available about the ichthyofauna of typical semi-arid rivers, although the regional diversity has been constantly threatened by human activities, mainly related to impoundment and construction of dams. The goal of the present work was to evaluate using different methods, the population genetic structure of a characin fish, Astyanax aff. bimaculatus, widespread throughout hydrographic basins of Bahia, Northeastern Brazil. Morphological (meristic and morphometric data), cytogenetic (karyotype and Ag-NOR), and molecular (RAPD and SPAR) analyses were carried out in specimens collected upstream and downstream of Pedra Dam, in the main channel of Contas River (Contas River Basin), and in the Mineiro stream, which belongs to the adjacent Recôncavo Sul basin. Few external differences were detected among populations, where the individuals collected upstream of Pedra Dam were slightly larger than the others. Cytogenetic data also showed a similar karyotypic pattern (2n=50; 6m+28sm+12st+4a; FN= 96) and NORs located on the short arms of up to two chromosome pairs, with numerical inter- and intra-populational variation. Nonetheless, RAPD and SPAR analyses differentiated reliably the three populations, revealing striking differences in the allele frequencies among the localities studied and a significant difference in population structure index (Fst=0.1868, P

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