Fragmenting fragments: landscape genetics of a subterranean rodent (Mammalia, Ctenomyidae) living in a human-impacted wetland

Abstract

Context: Anthropogenic activities have detrimental impacts on natural habitats and the species inhabiting them. In particular, habitat fragmentation has a profound effect on the dynamics and structure of natural populations and the species’ probability of persistence. Objectives: In this study, we examined which factors determine the population structure of Ctenomys species (tuco-tucos) at a local scale, evaluating the effects of natural and anthropic barriers on population divergence. Methods: We sampled tuco-tucos at 28 localities and genotyped 231 individuals at 11 microsatellite loci. Additionally, we built six spatial layers that describe the landscape inhabited by tuco-tucos, to evaluate the effects of habitat traits in the movement of individuals. We applied Bayesian clustering methods to infer the population structure, and landscape genetic tools to understand how landscape traits affect this structure. Results: We detected a high degree of population structure, even at a small spatial scale. Genetic structure seems to be influenced not only by current landscape configuration but also by their recent evolution. Altitude was the main contributing factor explaining this structure, with independent populations restricted to different sandy elevations in the region. However, anthropic activities were also shown to have had a significant effect on the differentiation among populations. Conclusions: The accelerated transformation process that the region is undergoing strongly conditions the dynamics of population differentiation in Ctenomys and reduces prospects of viability for the species. Our findings underscore the importance of incorporating variables that describe the temporal component of habitat changes in landscapes experiencing intense and recent transformation processes.