Cooperative Fish and Wildlife Research Units Program: Arizona
Education, Research and Technical Assistance for Managing Our Natural Resources

Bauder, J. M., Peterman, W. E., Spear, S. F., Jenkins, C. L., Whiteley, A. R., & McGarigal, K. 2021. Multiscale assessment of functional connectivity: Landscape genetics of eastern indigo snakes in an anthropogenically fragmented landscape in central Florida. Molecular Ecology, 30, 3422-3438.


Landscape features can strongly influence gene flow and the strength and directionof these effects may vary across spatial scales. However, few studies have evaluatedmethodological approaches for selecting spatial scales in landscape genetics analyses,in part because of computational challenges associated with optimizing landscaperesistance surfaces (LRS). We used the federally threatened eastern indigo snake(Drymarchon couperi) in central Florida as a case study with which to compare the importanceof landscape features and their scales of effect in influencing gene flow. Weused genetic algorithms (ResistanceGA) to empirically optimize LRS using categoricalland cover surfaces, multiscale resource selection surfaces (RSS), and four combinationsof landscape covariates measured at multiple spatial scales (multisurfacemultiscale LRS). We compared LRS where scale was selected using pseudo-andfulloptimization. Multisurface multiscale LRS received more empirical support than LRSoptimized from categorical land cover surfaces or RSS. Multiscale LRS with scale selectedusing full optimization generally outperformed those with scale selected usingpseudo-optimization.Multiscale LRS with large spatial scales (1200–1800m) receivedthe most empirical support. Our results highlight the importance of considering landscapefeatures across multiple spatial scales in landscape genetic analyses, particularlybroad scales relative to species movement potential. Different effects of scale onhome range-levelmovements and dispersal could explain weak associations betweenhabitat suitability and gene flow in other studies. Our results also demonstrate the importanceof large tracts of undeveloped upland habitat with heterogenous vegetationcommunities and low urbanization for promoting indigo snake connectivity.