Optimized resistance surfaces using two genetic distances, including the top three best-supported multi-surface models and five single models. The color gradient on maps represents resistance values from low (red) to high (blue). (a) Models optimized using ten-axes-based PCA Euclidean distance (DPCA). (b) Models optimized using Nei distance (DNei). Elev, elevation; Roug, roughness; Road, roads; Land, land cover; Dens, human density.