River barriers and cryptic biodiversity in an evolutionary museum

The Riverine Barriers Hypothesis (RBH) posits that tropical rivers 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 ver...

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Bibliographic Details
Published in:	Ecology and evolution Vol. 3; no. 3; pp. 536 - 545
Main Authors:	Voelker, G., Marks, B. D., Kahindo, C., A'genonga, U., Bapeamoni, F., Duffie, L. E., Huntley, J. W., Mulotwa, E., Rosenbaum, S. A., Light, J. E.
Format:	Journal Article
Language:	English
Published:	England John Wiley & Sons, Inc 01-03-2013 Blackwell Publishing Ltd Wiley
Subjects:	Afrotropics Avifauna Basins Biodiversity Birds Congo River cryptic diversity Forests Gene flow Genetic diversity Lice Museums Original Research Pleistocene river barriers River basins Rivers Species Tropical forests Understory Vertebrates Watersheds Wildlife conservation Congo River Congo Basin Amazon Basin South America, Amazon R Africa, Congo R river barriers Congo River cryptic diversity Afrotropics birds lice
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Summary:	The Riverine Barriers Hypothesis (RBH) posits that tropical rivers 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 assessment of the RBH has been conducted on birds in the Afrotropics, despite its rich avifauna and many Afrotropical bird species being widely 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 for their lice, based on four understory bird species collected from sites north and south 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 forests, in both understory birds and their lice. Therefore, these forests may not be “museums” of old lineages. Rather, substantial evolutionary diversification may have occurred in Afrotropical forests throughout the Pleistocene, supporting the Pleistocene 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 conservation. We find strong genetic evidence that the Congo River has served as a barrier to both birds and their ectoparasitic lice. Our results indicate that contemporaneous, Pleistocene lineage diversification has occurred across the Congo River.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Funding Information This study was supported by the United States National Science Foundation (DEB-0613668/0855466)
ISSN:	2045-7758 2045-7758
DOI:	10.1002/ece3.482