CONICET | Buscador de Institutos y Recursos Humanos

In fragmented habitats, landscape features strongly affect the genetic structure of populations. A very good example of fragmented habitat is the Iberá wetland, in Corrientes, Argentina. It is one of the largest wetlands in South America, located between three large rivers, covering more than 14,000 km2 and consisting of a vast mosaic of marshes, swamps and lagoons, of which nearly 60% are permanently inundated. Altogether 90% of the Iberá marsh is dominated by permanent or temporary wetlands and in the dry areas there is a predominance of sandy soils, sometimes forming extensive hillocks where it is posible to find populations of the perrensi lineage of the subterranean rodent Ctenomys. The perrensi group is a complex of three species (C. roigi, C. perrensi and C. dorbignyi), and several forms of uncertain taxonomic status. Because of limited availability of suitable dry habitat, Ctenomys populations are distributed patchily around the wetland and become connected or isolated over time, depending particularly on the precipitation regime. Given that this system is not only dynamic in space but also in time, we propose to understand temporal patterns of genetic variability among populations using museum samples belonging to the same localities that are being sampled at present. The use of this material in phylogeography and population dynamics is now widespread and it can be applied to the analysis of population declines and loss of genetic diversity, changes in connectivity following habitat fragmentation and detection of hybridization and introgression. We analyzed the temporal and spatial patterns of genetic variability together with the landscape structure in a group of populations from which we already had microsatellite variation suggesting hybridization between some of the perrensi forms. The results of the study will contribute to understand the relationships among populations connected by limited dispersal in a dynamic landscape that produces temporary barriers to gene flow.