title: New evidence for hybrid zones of forest and savanna elephants in Central and West Africa.
abstract: The African elephant consists of forest and savanna subspecies. Both subspecies are highly endangered due to severe poaching and habitat loss, and knowledge of their population structure is vital to their conservation. Previous studies have demonstrated marked genetic and morphological differences between forest and savanna elephants, and despite extensive sampling, genetic evidence of hybridization between them has been restricted largely to a few hybrids in the Garamba region of northeastern Democratic Republic of Congo (DRC). Here, we present new genetic data on hybridization from previously unsampled areas of Africa. Novel statistical methods applied to these data identify 46 hybrid samples--many more than have been previously identified--only two of which are from the Garamba region. The remaining 44 are from three other geographically distinct locations: a major hybrid zone along the border of the DRC and Uganda, a second potential hybrid zone in Central African Republic and a smaller fraction of hybrids in the Pendjari-Arli complex of West Africa. Most of the hybrids show evidence of interbreeding over more than one generation, demonstrating that hybrids are fertile. Mitochondrial and Y chromosome data demonstrate that the hybridization is bidirectional, involving males and females from both subspecies. We hypothesize that the hybrid zones may have been facilitated by poaching and habitat modification. The localized geography and rarity of hybrid zones, their possible facilitation from human pressures, and the high divergence and genetic distinctness of forest and savanna elephants throughout their ranges, are consistent with calls for separate species classification.
authors.affiliation: Center for Conservation Biology, Department of Biology, University of Washington, Box 351800, Seattle, WA, 98195-1800, USA.
authors.forename: Samrat
authors.initials: S
authors.lastname: Mondol
authors.affiliation: Department of Statistics and Department of Human Genetics, University of Chicago, Chicago, IL, 60637, USA.
authors.forename: Ida
authors.initials: I
authors.lastname: Moltke
authors.affiliation: Lukuru Wildlife Research Foundation, 1235 Poids Lourds, Kinshasa, Democratic Republic of Congo.
authors.forename: John
authors.initials: J
authors.lastname: Hart
authors.affiliation: Uganda Conservation Foundation, Plot 4, Henlon Close, Luthuli Avenue, Bugolobi, P.O. Box 34020, Kampala, Uganda.
authors.forename: Michael
authors.initials: M
authors.lastname: Keigwin
authors.affiliation: Department of Biostatistics, University of Washington, Box 357232, Seattle, WA, 98195-7232, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Brown
authors.affiliation: Department of Statistics and Department of Human Genetics, University of Chicago, Chicago, IL, 60637, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Stephens
authors.affiliation: Center for Conservation Biology, Department of Biology, University of Washington, Box 351800, Seattle, WA, 98195-1800, USA.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Wasser
mesh_terms: D000354:Africa, Western; D000818:Animals; D001499:Bayes Theorem; D002488:Central African Republic; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial / Q000235:genetics; D015023:Democratic Republic of the Congo; D004606:Elephants / Q000235:genetics*; D005298:Fertility; D065928:Forests; D005828:Genetics, Population; D065948:Grassland; D006824:Hybridization, Genetic; D016013:Likelihood Functions; D018895:Microsatellite Repeats; D008957:Models, Genetic; D017422:Sequence Analysis, DNA; D014454:Uganda; D014998:Y Chromosome / Q000235:genetics
chemical_list: D004272:DNA, Mitochondrial
keywords: Elephant hybridization; conservation; forest elephant; genetic population structure; savanna elephant