Cytotaxonomic Studies in Iberian Cyprinids. III. Karyology of Portuguese Populations ofBarbusCuvier, 1817, with Some Reconsiderations on The Karyological Evolution of Cyprinidae

Abstract

SUMMARYThe five species of Barbus living in Portuguese freshwaters were cytogenetically analysed using the air-dried method. They all have 2n = 100 complements and gross similarities, suggesting an interesting taxonomic affinity and the occurrence of delicate and punctual chromosome rearrangements on the respective differentiation process. Besides, they share some pecularities with the congeneric taxa until now examined, particularly with the Centro-European species, B. barbus. Based on several aspects, namely on the primitive and speciose character of the genus, a new model for the karyological evolution of the Cyprinidae is proposed. This one considers the existence of two types of polyploidy: one primarily derived from a Cypriniformes ancestor, and the other secondarily achieved from «diploidizied» species (2n = 50). The later, certainly less represented, must be considered due to the inequivocal presence of impair ploidy levels on natural populations and seems to be indirectly obtained by the acquisition of unisexual modes of reproduction. As for the genus now analysed, its inclusion on the group of primary polyploids is proposed.