The river barriers hypothèsis (RBH) posits that tropical river can be effective barriers to gene flow, based on observations that range boundaries often coincide with river barriers. Over the last 160 years, the RBH has received attention from various perspectives, with a particular focus on vertebrates in the amazon basin. To our knowledge, no molecular assesment of the RBH has been conducted on birds in the afrotropics, despite its rich avifauna and many afrotropical bird species being widzly distributed across numerous watersheds and basins. Here, we provide the first genetic evidence that an afrotropical river has served as a barrier for birds and their lice, base on four understory bird species collected from sites north and sauth of the congo River. Our results indicate near-contemporaneous, pleistocene lineage diversification across the Congo River in these species. Our results further indicate differing levels of genetic variation in bird lice; the extent of this variation appears linked to the life-history of both the host and the louse. Extensive cryptic diversity likely is being harbored in afrotropical forest, in both understory birds and their lice. Therefore, these forests may not be "museums" of old lineages. Rather, substantial evolutionary diversification may have accurred in afrotropical forests throughout the pleistocene, supporting the peistocene forest refuge hypothesis. Strong genetic variation in birds and their lice within a small part of the Congo Basin forest indicates that we may have grossly underestimated diversity in the afrotropics, making these forests home of substantial biodiversity in need of concervation.
River barriers and crypticbiodiversityin anevolutionary museum