Evaluating the functionality of expert-assessed wildlife corridors with genetic data from roe deer

Abstract

Traffic infrastructure such as fenced motorways may reduce functional connectivity by impeding the movement of wildlife and thus reduce gene flow across landscapes. This may result in increased genetic differentiation, eventually leading to decreasing genetic diversity in wildlife populations owing to genetic drift. Landscape managers and conservation agencies apply a range of measures to mitigate such adverse effects in intensively managed landscapes. Efficient measures to facilitate landscape permeability for wildlife include expert-assessed wildlife corridors. However, whether wildlife corridors are used as such and whether they fulfill their purpose remains largely unknown. Here, we evaluated whether the expert-based categorization of wildlife corridors into functional, impaired and interrupted held true in the Swiss Plateau by testing the landscape's permeability using genetic assessments. We identified the spatial genetic structure of roe deer (Capreolus capreolus) and tested, whether the estimated gene flow supported the expert categorization of wildlife corridors. Among the four study regions (ca. 300–2600km2), pairwise genetic differentiation was rather low (FST ranging between 0.008 and 0.0264). However, wildlife corridors identified as intact on the basis of expert evaluation showed higher gene flow between populations of roe deer (mean FST=0.008) than corridors classified as impaired or interrupted (mean FST=0.022). Thus, expert judgement on the functionality of wildlife corridors could be generally confirmed by our genetic assessment on the permeability of landscapes for roe deer. This shows that genetic methods may constitute a useful set of tools to identify the state of management measures and to prioritize action plans for maintaining functional wildlife corridors across landscapes.