Phylogenetic relationships of mediterranean Mullidae species (Perciformes) inferred from genetic and morphologic data

Abstract

Genetic and morphological divergence and phylogenetic relationships of four species Mullus barbatus, Mullus surmuletus, Upeneus moluccensis, Upeneus pori and one subspecies M.b. ponticus of Mullus were investigated using 12 enzymatic systems, corresponding to 17 putative loci. Eight loci (AAT-1, AAT-2, ADH, GAPDH, G6PDH, IDHP, PGI-2, SOD) were found to be polymorphic in at least one species, while the remaining nine (mAAT, CK-1, CK-2", G3PDH, MDH, ME-1, ME-2, PGI-1, PGM) were monomorphic in all species. Several loci showed different electrophoretic patterns among species and thus can be used in species taxonomy as diagnostic markers. The PGM and SOD loci proved to be especially species-specific. Fisher's exact test revealed overall highly significant allele frequency differences between M. barbatus and M. b. ponticus (P<0.001). Pairwise comparisons of genetic distance were found to be 0.034 between M. barbatus and M. b. ponticus, and 0.341 between M. barbatus and M. surmuletus within the genus Mullus. Relatively higher genetic differentiation (D=0.628) was observed between U. moluccensis and U. pori. For intergeneric comparisons, the highest genetic distance (1.250) was detected between M. surmuletus and U. pori, and the lowest (D=1.056) was observed between M. surmuletus and U. moluccensis. Remarkably U. pori was genetically the most distinct species from the genus Mullus. A neighbour-joining analysis of genetic data separated the two genera: M. barbatus and M. b. ponticus clustered as the closest taxonomic assemblage, which was a sister group to M. surmuletus in the first branch, while U. moluccensis and U. pori clustered more divergently in the second branch. Morphological data using meristic characters was congruent with the genetic data and revealed similar patterns of relationships among four Mullidae species.