The article by Brad H. McRae and Paul Beier explores the application of circuit theory to predict gene flow in plant and animal populations, addressing the challenge of maintaining connectivity for ecological processes like dispersal and gene flow in fragmented landscapes. The authors introduce the Isolation-by-Resistance (IBR) model, which uses resistance distance, a metric based on electrical circuit theory, to integrate all possible pathways connecting populations. This model outperforms conventional gene flow models, such as isolation-by-distance (IBD) and least-cost path (LCP) models, by considering multiple pathways and wider habitat swaths, leading to more accurate predictions of gene flow. The IBR model is tested using data from threatened mammal and tree species, revealing that barriers are less significant in structuring populations than previously thought. The authors conclude that circuit theory provides a robust method for bridging landscape and genetic data, offering significant promise in ecology, evolution, and conservation planning.The article by Brad H. McRae and Paul Beier explores the application of circuit theory to predict gene flow in plant and animal populations, addressing the challenge of maintaining connectivity for ecological processes like dispersal and gene flow in fragmented landscapes. The authors introduce the Isolation-by-Resistance (IBR) model, which uses resistance distance, a metric based on electrical circuit theory, to integrate all possible pathways connecting populations. This model outperforms conventional gene flow models, such as isolation-by-distance (IBD) and least-cost path (LCP) models, by considering multiple pathways and wider habitat swaths, leading to more accurate predictions of gene flow. The IBR model is tested using data from threatened mammal and tree species, revealing that barriers are less significant in structuring populations than previously thought. The authors conclude that circuit theory provides a robust method for bridging landscape and genetic data, offering significant promise in ecology, evolution, and conservation planning.