Habitat fragmentation mediates the frequency of cytogenetic endpoints in small non-flying mammals in agriculture landscapes in Cerrado

Abstract

Intensive farming is associated with habitat loss, fragmentation, and high inputs of pesticides that, added to the environmental changes, are associated with increased levels of physiological stress in vertebrates. High levels of stress and pesticides stored in organisms’ body can cause several physiological and behavioral disruptions, including DNA and chromosome damages, i.e., cytogenetic endpoints, that can be used as biomarkers to detect bioaccumulation of pesticides and stress exposure. Here, we address how agricultural landscapes influence the frequency of cytogenetic endpoints in small non-flying mammals in Cerrado ecoregion. We sampled small mammals in 17 agricultural landscapes in Brazilian Cerrado, and analyzed the cytogenetic endpoints of 75 individuals from 13 different species using mouth swab to test the hypothesis that landscapes with higher habitat amount and aggregation, and low fragmentation, heterogeneity and patch shape index have lower frequency of cytogenetic endpoints. We found that habitat amount and aggregation were associated with lower frequency of cytogenetic endpoints, most likely due to smaller distance between remnant habitat patches, which can facilitate the movement of mammals in the landscape, and reduce stress and direct pesticide exposure. The number of patches, patch shape index, and landscape heterogeneity was associated with higher frequency of cytogenetic endpoints, most likely due to edge effects increasing environmental stress, which leads to higher frequency of cytogenetic endpoints. Our findings suggest the need for policies including incentives to forest and savanna restoration as a strategy that can improve remnant shape locally, increase habitat amount and aggregation, and decrease landscape heterogeneity due to the increase in habitat amount at regional scale. Such measures can help protecting small mammals’ health by minimizing environmental stressors. Additionally, targeted restoration efforts to increase aggregation among habitat patches may facilitate small mammals’ movements across landscapes, especially those with low dispersal capacity.