title: Comparative Phylogeography of Ethiopian anurans: impact of the Great Rift Valley and Pleistocene climate change.
abstract: The Ethiopian highlands are a biodiversity hotspot, split by the Great Rift Valley into two distinct systems of plateaus and mountains. The Rift Valley is currently hot and dry and acts as a barrier to gene flow for highland-adapted species. It is however unlikely that the conditions in the Rift were inhospitable to highland species during the entire Pleistocene. To assess the significance of the Ethiopian Rift as a biogeographic barrier as well as the impact Pleistocene climatic changes have had on the evolution of Ethiopian organisms, we performed phylogeographic analyses and developed present and past niche models on seven anuran species with different elevational and ecological preferences.
  
  
  
  We found that highland species on the east and the west sides of the Rift are genetically differentiated and have not experienced any detectable gene flow for at least 0.4 my. In contrast, species found at elevations lower than 2500 m do not show any population structure. We also determined that highland species have lower effective population sizes than lowland species, which have experienced a large, yet gradual, demographic expansion, starting approximately half a million year ago.
  
  
  
  The pattern we report here is consistent with the increasingly warmer and drier conditions of the Pleistocene in East Africa, which resulted in the expansion of savanna, the fragmentation of forests and the shrinking of highland habitats. Climatic niche models indicated that the Rift is currently non suitable for most of the studied species, but it could have been a more permeable barrier during the Last Glacial Maximum. However, considering the strong genetic structure of highland species, we hypothesize that the barrier mechanisms at the Rift are not only climatic but also topographical.
authors.affiliation: Department of Biology, Queens College, City University of New York, Flushing, NY, USA.|Ecology, Evolution and Behavior Program, Graduate Center, City University of New York, New York, NY, USA.
authors.forename: Xenia
authors.initials: X
authors.lastname: Freilich
authors.affiliation: Department of Biology, Queens College, City University of New York, Flushing, NY, USA.|Ecology, Evolution and Behavior Program, Graduate Center, City University of New York, New York, NY, USA.
authors.forename: José D
authors.initials: JD
authors.lastname: Anadón
authors.affiliation: Department of Biology, Queens College, City University of New York, Flushing, NY, USA.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Bukala
authors.affiliation: Department of Biology, Queens College, City University of New York, Flushing, NY, USA.
authors.forename: Ordaliza
authors.initials: O
authors.lastname: Calderon
authors.affiliation: Department of Biology, Queens College, City University of New York, Flushing, NY, USA.
authors.forename: Ronveer
authors.initials: R
authors.lastname: Chakraborty
authors.affiliation: New York University Abu Dhabi, P.O. Box 129188, Abu Dhabi, United Arab Emirates. sb5272@nyu.edu.
authors.forename: Stéphane
authors.identifier: 0000-0002-8760-1284
authors.initials: S
authors.lastname: Boissinot
mesh_terms: D000351:Africa, Eastern; D000818:Animals; D001001:Anura / Q000235:genetics*; D044822:Biodiversity; D005075:Biological Evolution; D057231:Climate Change; D004272:DNA, Mitochondrial / Q000235:genetics; D017753:Ecosystem; D065928:Forests; D051456:Gene Flow; D014644:Genetic Variation; D010802:Phylogeny; D058974:Phylogeography
chemical_list: D004272:DNA, Mitochondrial
keywords: Amietia; Anura; East Africa; Ethiopia; Great Rift Valley; Leptopelis; Phylogeography; Ptychadena; Tomopterna