Polymerase chain reaction banding patterns of the 5S rDNA gene as a diagnostic tool for the discrimination of South American mullets of the genus Mugil

The mullets of the family Mugilidae, and in particular the species of the genus Mugil, are characterized by highly conserved morphological features, which hinder taxonomic classification considerably. Given this, the present study aimed to evaluate the efficiency of the 5S rDNA gene – a rapid and low cost genotyping marker – for the discrimination of Mugil species. Variations in the banding pattern permitted the reliable differentiation of four species –Mugil curema, Mugil incilis, Mugil sp. and Mugil hospes– although those of three others (Mugil liza, Mugil platanus and Mugil cephalus) were identical. This suggests that these three forms have diverged very recently, on a time scale that has limited changes in the length of the fragments of the 5S rDNA gene. The results of the study confirm the efficiency of this marker as a diagnostic tool for the identification of Mugil species, and its usefulness for population management and pisciculture, an important economic activity involving this group.