In this study, the RAPD technique was used to analyze the genetic structure of populations of the fish Astyanax altiparanae (Characidae, Tetragonopterinae) living in the lower, middle and upper Paranapanema River, Brazil. The aim was to assess this structure regarding fish handling and conservation programs. The genetic variability (P) was found to be 42.64%, 75% and 75% in the low, middle and upper reaches, respectively. The dendrogram of genetic similarity, obtained by comparative analysis of the sets of samples from the three sites, showed the formation of three clusters. All of the genetic parameters used indicate that the population in the lower Paranapanema is genetically different from those in the middle and upper sections. The theta P test shows... |