Abstract
Mitochondrial sequences contribution to dismantling the polyploid genus Barbus (Cyprinidae, Cyprininae) constitutes a diversified assemblage of about 800 species inhabiting Eurasia and Africa. In several cases, the mere possession of barbels was deemed enough to classify numerous species. In the genus in the last ten years, the phylogeny of Barbus, based on molecular markers, improved remarkably, and progress in karyology showed entire tetraploid and hexaploid lineages of generally limired geographic range which allowed interesting deductions on their evolution. Phylogenetic analysis of these species started using allozymes. These markers were efficient in detecting sibling species and hybridization events, and in describing phylogenetic relationships among related species having the same ploidy level. However, due to the " functional diploidisation" phenomena which occurred after ancestral polyploidisation, calculation conventions are necessary, i. e. "minimising" and "maximising" coding methods. If species of different ploidy levels are included in the analysis, these conventions can become more influential than the data themselves when used for large phylogenetic constructions. While nuclear data are most informative in population genetics, the mitochondrial genes sequences (mainly of the cytochrome b gene) allowed the avoidance of statistical biases associated with the nuclear markers. As a result, the phylogenetic relationships between lineages established in several geographic areas showed that conventional taxonomy needed substantial improvement. In particular, the genus Barbus must be limited to peri-Mediterranean tetraploid species. Mitochondrial markers proved a powerfull tool in the detection and description of the main biogeographic lineages and in the redefinition of this problematic group.