A virus reveals population structure and recent demographic history of its carnivore host

This influential study used feline immunodeficiency virus as a fast-evolving genetic marker to reconstruct the population history of its puma hosts in the American West. Because the virus mutates far quicker than the host genome, its sequences captured recent migration, colonization and demographic change invisible to slower host markers. By sampling pumas across the region and building viral phylogenies, the authors inferred patterns of cougar movement and recent population establishment, including post-recolonization spread. The work demonstrated a powerful general principle: a co-transmitted pathogen can serve as a high-resolution tracer of host ecology and dispersal. It bridged disease ecology and population genetics, showing how endemic lentiviruses double as natural tags for studying the movements of elusive wild felids.