A southern California freeway is a physical and social barrier to gene flow in carnivores

Riley and colleagues combined radio-telemetry with genetic analysis of bobcats and coyotes split by a major Los Angeles freeway, showing that the road acted as both a physical and a social barrier to movement and gene flow. Although a few animals crossed, the genetic data revealed that crossers rarely bred across the divide, so the freeway structured the population into genetically distinct groups despite the small distances involved. The study was an early, influential demonstration that roads fragment carnivore populations not only by blocking movement but by disrupting the social and reproductive processes that gene flow depends on. It set the stage for later puma research in the same landscape and helped establish freeways as potent agents of genetic isolation for urban-adjacent felids.