A southern California freeway as a physical and social barrier to carnivore gene flow

This landmark genetic study showed that a multi-lane freeway sharply restricted movement and gene flow in bobcats and coyotes in the fragmented hills north of Los Angeles. Combining radio-telemetry with microsatellite genotyping, the authors found that the few animals crossing the freeway rarely bred across it, so populations on either side diverged genetically despite the road being permeable to occasional individuals. The concept of a road as both a physical and a social barrier reframed how transportation infrastructure fragments carnivore populations, and it foreshadowed the freeway-isolation crisis later documented for Santa Monica Mountains pumas, motivating wildlife-crossing infrastructure across the region.