NUCLEAR-DNA CONTENT OF 30 SPECIES OF NEOTROPICAL FISHES

The present paper reports nuclear DNA content in 30 Neotropical freshw ater fish species and summarizes the data on other Neotropical species presented in the literature. Among Neotropical fishes, the nuclear DN A content ranges from 1.04 +/- 0.09 pg/nucleus in Corydoras cf. simula tus (2n = 62) to 248.0 pg/nucleus in Lepidosiren paradoxa (2n = 38). A general analysis of the data obtained in the present study for each s pecies showed that DNA measurements were practically constant at the i ndividual level, while significant differences were observed among ind ividuals of the same population. This observation was valid for all sp ecies analyzed and was more evident in those species that presented ot her karyotypic particularities such as sex chromosomes or supernumerar y chromosomes. The importance of changes in nuclear DNA content in the evolutionary process of Neotropical fishes is discussed.