Dna repetitivo na evolução cromossômica de cynodontidae eigenmann, 1910

Abstract

Cynodontidae is a family of carnivorous fishes of the order Characiformes formed by eight species, grouped in the genera Cynodon, Raphiodon and Hydrolycus, together with Hemiodontidae, Serrasalmidae, Parodontidae, Prochilodontidae, Chilodontidae, Curimatidae, and Anostomidae form the superfamily Curimatoidea. Although knowledge about the phylogenetic position of this family has advanced, little is known about chromosomal evolution. Thus, this study brings evidence of the karyotype evolution of the Cynodontidae family from the cytogenomic characterization of three species in the Amazon and the study of their relationships. For that, conventional cytogenetic data and repetitive DNA mapping (5S and 18S rDNA, Rex 1, 3 and 6 and microsatellite sequences) are presented in a species of each genus of Cynodontidae (Cynodon gibbus, Raphiodon vulpinus and Hydrolycus armatus) with the objective to elucidate the evolutionary mechanisms involved in karyotype differentiation. The three species studied here have a diploid number equal to 54 and variation in the karyotype macrostructure (FN = 104, 106, 108), indicating the occurrence of non-Robertsonian rearrangements. In addition, we present the first report of differentiated sex chromosomes within Cynodontidae, in C. gibbus, which presented sex chromosomes of the ZZ/ZW type with independent origin in Curimatoidea and showed that repetitive DNAs played a fundamental role in the differentiation of these sex chromosomes.