The evolution of a highly speciose group in a changing environment: are we witnessing speciation in the Iberá wetlands?

MARIA JIMENA GÓMEZ FERNÁNDEZ; OSCAR E. GAGGIOTTI; PATRICIA MIROL

MOLECULAR ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. 21 p. 3266 - 3282

0962-1083

Delimiting species is very conflicting in the case of very young taxa that are in the process of diversification, and even more difficult if the species inhabit a heterogeneous environment. In this case, even population delimitation is controversial. The South American genus of subterranean rodents Ctenomys is highly speciose, with 62 species that appeared in the lapse of 3 million years. Within the genus, the “perrensi” group, formed by three named species and a group of forms of unknown taxonomic status, inhabits the Iberá wetland, in northern Argentina. Almost every locality shows a particular chromosomal complement. In order to understand the relationships and the evolutionary process among species and populations, we examined mitochondrial DNA sequences and microsatellite genotypes. We found an isolation by distance pattern with evidence of cluster-like behaviour of the system. The mitochondrial DNA phylogeny evidenced two different groups, separated by one of the main rivers of the region. Clustering methods delimited 12 different populations and 5 metapopulation lineages that seem to be evolving independently. We found evidence of ancient migration among localities at the center of the distribution but no signs of actual migration among the 12 delimited clusters. Some of the genetic clusters found included localities with different chromosomal numbers, which points to the existence of gene flow despite chromosomal variation. The evolutionary future of these five lineages is controlled by the dynamics of their habitat, if stable they may become distinct species, otherwise they may collapse into a hybrid swarm forming a single evolving metapopulation