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

GÓMEZ FERNÁNDEZ JIMENA; GAGGIOTTI OSCAR; MIROL PATRICIA

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 theprocess of diversification, and even more difficult if the species inhabit a heterogeneousenvironment. In this case, even population delimitation is controversial. The SouthAmerican genus of subterranean rodents Ctenomys is highly speciose, with 62 speciesthat appeared in the lapse of 3 Myr. Within the genus, the ‘perrensi’ group, formed bythree named species and a group of forms of unknown taxonomic status, inhabits theIbera´ wetland, in northern Argentina. Almost every locality shows a particularchromosomal complement. To understand the relationships and the evolutionary processamong species and populations, we examined mitochondrial DNA sequences andmicrosatellite genotypes. We found an isolation-by-distance pattern with evidence ofcluster-like behaviour of the system. The mitochondrial DNA network revealed twodifferent groups, separated by one of the main rivers of the region. Clustering methodsdelimited 12 different populations and five metapopulation lineages that seem to beevolving independently. We found evidence of ancient migration among localities at thecentre of the distribution but no signals of current migration among the 12 delimitedclusters. Some of the genetic clusters found included localities with different chromosomalnumbers, which points to the existence of gene flow despite chromosomalvariation. The evolutionary future of these five lineages is controlled by the dynamics oftheir habitat: if stable, they may become distinct species; otherwise, they may collapseinto a hybrid swarm, forming a single evolving metapopulation.