Biodiversity loss in a gradient of urbanization: rodent community structure in a subtropical area of Northern Argentina

Abstract Urbanization promotes habitat degradation because it involves irreversible processes that homogenize habitats and favor the exclusion of native species. This research evaluates rodent community structure at different levels of urbanization in Misiones, Argentina. We expect that rodent communities are less diverse in more highly urbanized areas and that communities differ between each level of urbanization. To assess these hypotheses, rodent capture sessions were carried out from July 2017 to March 2020, totaling 21,985 trap-nights. Alpha and beta diversity were calculated for each level of urbanization. We captured a total of 684 individuals belonging to 8 sylvan-native and 2 commensal-exotic species. Species richness was greatest and evenness was lowest in natural protected areas. The native species Akodon montensis was the most abundant, while the remaining 7 native species represented less than 23% of the total of captures. The rural area showed the second-highest richness, and the community was principally represented by 2 native and 2 exotic species. The periurban area was ranked third in richness and with the highest evenness, dominated by A. montensis followed by Mus musculus and Rattus rattus. The urban area exhibited the lowest richness represented only by the 2 commensal-exotic species. In agreement with our expectations, these results show a negative association between urbanization level and small rodent diversity, evidenced by a reduction in the number of native species in highly urbanized areas.