Mitochondrial evidence for the origin of hamadryas baboons Derek E. Wildman, a,b,h, * Thore J. Bergman, c Abdulwali al-Aghbari, d,e Kirstin N. Sterner, a,h Timothy K. Newman, f Jane E. Phillips-Conroy, g Clifford J. Jolly, a,h and Todd R. Disotell a,h a Department of Anthropology, New York University, USA b Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA c Department of Biology, Washington University, St. Louis, MO, USA d Department of Animal Science, Oregon State University, USA e Faculty of Agriculture, SanaÕa University, SanaÕa, Republic of Yemen f Laboratory of Neurogenetics, NIAAA/NIH, Rockville, MD, USA g Department of Anatomy & Neurobiology, Washington University School of Medicine, St. Louis, MO, USA h New York Consortium in Evolutionary Primatology (NYCEP), USA Received 14 August 2003; revised 1 December 2003 Available online 5 March 2004 Abstract Baboons (Mammalia: Primates, Papio) are found primarily on the continent of Africa, but the range of hamadryas baboons (Papio hamadryas) extends to the Arabian Peninsula, and the origin of Arabian populations is unclear. To estimate the timing of the divergence between Arabian and African hamadryas populations we analyzed mitochondrial DNA (mtDNA) sequences from in- dividuals of Arabian and African origin, and from representatives of the other major baboon taxa. The oldest hamadryas mito- chondrial lineages in the Arabian Peninsula form an ancient trichotomy with the two major African lineages. This suggests that Arabia was colonized by hamadryas very soon after the appearance of the distinctive hamadryas phenotype, both events perhaps coinciding with a mid-Pleistocene stage of dry climate and low sea-level. The most closely related Arabian and African mtDNA haplotypes coalesce at approximately 35 ka, suggesting that no gene flow between African and Arabian baboons has occurred since the end of the last ice age, when a land bridge at the southern sill of the Red Sea was submerged. The mitochondrial paraphyly of Ethiopian hamadryas and anubis (P. anubis) baboons suggests an extensive and complex history of sex-specific introgression. Ó 2004 Elsevier Inc. All rights reserved. Keywords: Baboon; Biogeography; Arabia; Africa; mtDNA; Phylogeography 1. Introduction Five living species are commonly distinguished in the baboon genus Papio, although many more morpholog- ically distinct allotaxa are recognizable (Groves, 2001; Jolly, 1993). Of these, the hamadryas baboon (Papio hamadryas) is distinguished by a suite of behavioral and morphological autapomorphies (Jolly, 2001; Kummer, 1968). In spite of this distinctiveness, hamadryas ba- boons hybridize readily with anubis baboons (Papio anubis) where their ranges meet in Ethiopia, and surveys in the hybrid zone document local genetic introgression. (Nagel, 1973; Newman, 1997; Phillips-Conroy et al., 1991; Shotake et al., 1977; Woolley-Barker, 1999). Pre- vious molecular-genetic studies have concluded that hamadryas baboons comprise a sister group of a clade consisting of anubis (Papio anubis) and yellow (Papio cynocephalus) baboons (Wildman, 2000; Williams- Blangero et al., 1990), and that Ethiopian anubis and hamadryas baboons have been separate lineages for approximately 350 ka. (Nakamura et al., 1983; Newman et al., 2003; Shotake et al., 1977; Wildman, 2000). The hamadryas is the only Papio baboon whose range extends beyond the African continent, being found both in the Horn of Africa and across the Red * Corresponding author. Fax: 1-313-577-5218. E-mail address: dwildman@genetics.wayne.edu (D.E. Wildman). 1055-7903/$ - see front matter Ó 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2003.12.014 Molecular Phylogenetics and Evolution 32 (2004) 287–296 MOLECULAR PHYLOGENETICS AND EVOLUTION www.elsevier.com/locate/ympev