CONICET | Buscador de Institutos y Recursos Humanos

Dispersal and gene flow are key processes for the persistence of populations, because theyenable the maintenance of large effective population sizes and the recolonization of emptypatches. Therefore, assessing how these processes are modulated by landscape characteristicsis crucial in a context of anthropogenic landscape change and habitat fragmentation.We used several spatial genetics approaches to study the genetic structure of populations ofthe rodent Calomys venustus in an intensively managed agroecosystem in central Argentina.The landscape consists of crop fields separated by a network of borders (narrowstrips of vegetation along fence lines, roads and water streams) providing habitat andstructural connectivity for species, crossed by dirt roads and a few paved roads and waterstreams. We tested the hypothesis that this species, despite showing a strong preferencefor borders, perceives the matrix as a lower-quality habitat that does not impede dispersal.Our results showed that functional connectivity was not limited to borders, gene flow wasnot restricted by any of the landscape elements considered in this study, and suggestedthat long distance movements would not be uncommon. The genetic structure of C. venustusconsisted of groups of genetically similar individuals that were remarkably variablein spatial extent, were genetically differentiated, followed an isolation by distance pattern,but were not delimited by any apparent landscape features that may restrict dispersal andexplain their boundaries. Cluster boundaries could result from the interaction between thegrain of resource patches and the spatial scale of the range of perception of individuals,determining that habitat-matrix boundaries would be crossed in some places but not in others.Our results add to the growing list of cases of higher-than-expected dispersal ability inspecies with strong habitat preferences.

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