Assessing the effects of land-use intensity on small mammal community composition and genetic variation in Myodes glareolus and Microtus arvalis across grassland and forest habitats

Context Land-use intensification can alter small mammal community composition and induce loss of genetic variation in remaining populations. Fragmented landscapes favor generalist and synanthropic species, which are potential reservoirs of pathogens and pose risks to agriculture and forestry. Objectives This study aimed to evaluate the effects of land-use intensity on small mammal diversity in grassland and forest habitats, as well as on genetic variation patterns driven by geographic (isolation by distance) and environmental distance (isolation by resistance) factors. Methods We analysed differences in small mammal community diversity on grassland and forest plots with varying land-use intensities. Genetic analyses were conducted on Myodes glareolus and Microtus arvalis populations from each habitat, using microsatellites. Maximum Likelihood Population Effects models were employed to elucidate gene flow patterns and significant differences in genetic structure based on land-use intensity. Results Small mammal communities in grasslands were significantly less diverse than in forests. Land-use intensity had a significant effect on diversity within grassland but not within forest habitats. M. glareolus showed three genetic groups, while M. arvalis displayed no discernible population structure or landscape-related pattern. Land-use intensity did not significantly influence the genetic structure of either species. Gene flow in M. glareolus is best described by the IBR model. Conclusion Land-use intensity significantly affects small mammal community composition, particularly in grasslands. Neither species’ genetics is directly impacted by land-use intensity but rather by landscape connectivity and distance. Risk assessments for rodent-borne zoonotic pathogens and crop damage should be framed within a habitat connectivity context.