In this study, we used microsatellite markers to examine the genetic structures of Centropomus undecimalis (Bloch, 1792) and Epinephelus marginatus (Lowe, 1834) populations collected from artisanal fishing sites along a stretch of coastline in southeastern Brazil. Based on F-statistics, there was no significant genetic differentiation evident in any C. undecimalis samples (FST=0.012). However, Bayesian clustering, principal component analysis (PCA) and discriminant analysis of principal components (DAPC) results suggested that there were most likely two clusters, with no relation to geographic areas. The bottleneck results showed no significant values and the effective population sizes (Ne) for the two genetically differentiated groups were large and similar. In contrast, for E. marginatus populations, the microsatellite loci showed no population subdivisions. The FST value was low and non-significant (FST=0.008), a Bayesian analysis indicated one cluster, and a PCA showed that all samples from different geographical sites shared the same genetic structure. The bottleneck results exhibited significant differences, and a low Ne was observed. The results of the genetic study of these two species along the southeastern Brazilian coast suggest that the distinct genetic structure of each species should be taken into account as management units for the conservation of their genetic diversities. |