Mitochondrial RFLP markers were developed to examine whether Plagioscion squamosissimus (Heckel, 1840) is invasive in natural environments of the congener P. ternetzi in the Paraná river, in southern Brazil. Specimens of P. squamosissimus and of the putative P. ternetzi (Boulenger, 1895) were obtained from the Negro river (Manaus, Amazonas, Brazil) and from Paraná river, respectively. Fragments of the cytochrome b gene (900bp) were amplified by PCR and four restriction enzymes (Eco RI, Mbo I, Bam HI and Alu I) yielded the mitochondrial markers. An additional RFLP analysis with a cytochrome b gene sequence of Plagioncion sp. from GeneBank was carried out to validate the prior analysis. No genetic differentiation was found among either sample. While molecular variation in the cytochrome b analysis was no substantial among individuals, the combined analysis was important for demonstrating that there is no evidence for differentiation of the putative sample P. ternetzi from that of P. squamosissimus. The ecological implications of the introduced occurrence of P. squamosissimus, as well as the role of molecular taxonomic approaches for biodiversity studies are discussed.
Plagioscion squamosissimus; Cytochrome b; genetic identity; biological invasions
