Hybridization between subterranean tuco-tucos (Rodentia, Ctenomyidae) with contrasting phylogenetic positions.

Abstract

Reproductive compatibility usually decreases according to increasing genetic diference and the time of divergence between species. However, the amount of modifcation required to infuence hybridization may vary in diferent species. Thus, it is extremely important to conduct studies that seek to understand what and how variables infuence the reproductive isolation of species. We have explored a system involving two species of subterranean rodents that present morphological, karyotypic, and evolutionary history diferences and are capable of generating hybrids. To gain insight into the karyotype organization of genus Ctenomys, we examined the chromosome evolution by classical and molecular cytogenetics of both parental species and hybrids. Furthermore, we have used diferent approaches to analyze the diferences between the parental species and the hybrids, and determined the origin of the hybrids. The results of our work demonstrate unequivocally that some species that present extensive diferences in chromosome organization, phenotype, evolutionary history, sperm morphology and genetic, which are usually associated with reproductive isolation, can generate natural hybrids. The results also demonstrate that females of both species are able to generate hybrids with males of the other species. In addition, the chromosome-specifc probes prepared from Ctenomys famarioni provide an invaluable tool for comparative cytogenetics in closely related species.