Rivers constrain female but not male dispersal and genetic structure in brown bears

Understanding landscape barriers to connectivity is essential for wildlife conservation. Rivers may restrict movement and gene flow in brown bears (Ursus arctos), yet their impact remains unclear. Using SNP-genotypes from 519 individuals in northern Sweden, we examined sex-specific dispersal and genetic structure relative to rivers. Males dispersed farther and crossed rivers more often than females, indicating rivers act as semipermeable barriers primarily for females. Genetic structure was weak for females and absent for males.