Genetic diversity of the small characid fish Astyanax sp., and its significance for conservation Daniele Aparecida Matoso 1 , Roberto Ferreira Artoni 1 & Pedro Manoel Galetti Jr 2, * 1 Department of Structural, Molecular and Genetic Biology, Universidade Estadual de Ponta Grossa, Campus de Uvaranas, 84030-900, Ponta Grossa, PR, Brazil 2 Department of Genetics and Evolution, Universidade Federal de Sa ˜o Carlos, 13565-905, Sa ˜o Carlos, SP, Brazil (*Author for correspondence: Tel.: +55-16-260-8110, Fax: +55-16-261-3176, E-mail: galettip@power.ufscar.br) Received 26 November 2002; in revised form 1 March 2004; accepted 27 April 2004 Key words: fish, Astyanax sp., conservation genetics, Vila Velha State Park, RAPD Abstract Genetic variations in Astyanax sp. fish from Vila Velha State Park and Tibagi river (Parana´, Brazil) were analyzed by RAPD. Intrapopulational genetic similarity was analyzed at three collection sites. The higher RAPD polymorphism observed at site 3 (Tibagi river) suggests either an overlapping of structured pop- ulations or the presence of coexisting morphotypes at this site. Significant p values obtained by homoge- neity tests revealed an unequal loci proportion among populations. The significance of similarity coefficients indicated that the differences observed among populations are relevant. These findings provide important information for the management and conservation of the species analyzed and for genetic variability maintenance programs. Introduction Situated in the region of Campos Gerais in southern Brazil, the Vila Velha State Park (VVSP) is characterized by the presence of sinkholes whose origin, according to Soares (1989), can be traced to alterations in the hydrostatic level of underground waters. These wells possess deep water columns (50 m) sheltering fish populations of the genus Astyanax, comprising isolated populations in each tumbling well (Fig. 1). How these fish appeared in the wells and in what period remains an open question. In addition to the sinkholes, the Dou- rada lagoon is connected by the Gabiroba river to the Tibagi river, which constitutes the main water system in this region. The Astyanax species are widely distributed in Neotropical rivers, displaying extensive morpho- logical and chromosomal variations, and are therefore characterized as a ‘complex species’ (Moreira-Filho & Bertollo, 1991). Difficulties in their taxonomic identification (Garutti & Britski, 2000), distinctions among sympatric cytotypes (Moreira-Filho & Bertollo, 1991), and the con- fused determination of their phyletic origin are the most common problems faced by researchers who study these fish. Due to the peculiarities of the region in question, the present work aimed to assess the intra- and interpopulational genetic variations in Astyanax sp. from the VVSP. Material and methods Thirty-six Astyanax sp. individuals, collected at three sites in the VVSP and the upper Tibagi river: sinkhole 2 (site 1), Dourada lagoon (site 2) and the main channel of the Tibagi river (site 3), were analyzed. DNA was sampled from hepatic tissue, Hydrobiologia 527: 223–225 2004. Ó 2004 Kluwer Academic Publishers. Printed in the Netherlands. 223