The evolution of a highly speciose group in a changing environment: are we witnessing speciation in the Iberá wetlands?
Article first published online: 15 JUN 2012
© 2012 Blackwell Publishing Ltd
Volume 21, Issue 13, pages 3266–3282, July 2012
How to Cite
FERNÁNDEZ, M. J. G., GAGGIOTTI, O. E. and MIROL, P. (2012), The evolution of a highly speciose group in a changing environment: are we witnessing speciation in the Iberá wetlands?. Molecular Ecology, 21: 3266–3282. doi: 10.1111/j.1365-294X.2012.05598.x
- Issue published online: 21 JUN 2012
- Article first published online: 15 JUN 2012
- Received 17 August 2011; revision received 14 March 2012; accepted 23 March 2012
- fragmented habitat;
- metapopulation lineages;
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 Myr. 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. 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 network revealed two different groups, separated by one of the main rivers of the region. Clustering methods delimited 12 different populations and five metapopulation lineages that seem to be evolving independently. We found evidence of ancient migration among localities at the centre of the distribution but no signals of current 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.