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Rivers, not refugia, drove diversification in arboreal, sub-Saharan African snakes
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  • Kaitlin Allen,
  • Eli Greenbaum,
  • Paul Hime,
  • Walter Paulin Tapondjou Nkonmeneck ,
  • Viktoria Sterkhova,
  • Chifundera Kusamba,
  • Mark-Oliver Rödel,
  • Johannes Penner,
  • Townsend Peterson,
  • Rafe Brown
Kaitlin Allen
University of Kansas
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Eli Greenbaum
University of Texas at El Paso
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Paul Hime
University of Kansas
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Walter Paulin Tapondjou Nkonmeneck
University of Kansas
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Viktoria Sterkhova
University of Kansas
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Chifundera Kusamba
Centre de Recherche en Sciences Naturelles
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Mark-Oliver Rödel
Museum fur Naturkunde - Leibniz-Institut fur Evolutions- und Biodiversitatsforschung
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Johannes Penner
Museum für Naturkunde - Leibniz-Institut für Evolutions- und Biodiversitätsforschung
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Townsend Peterson
University of Kansas
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Rafe Brown
University of Kansas
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Abstract

The relative roles of rivers and refugia in shaping the high levels of species diversity in tropical rainforests has been widely debated for decades. Only recently has it become possible to take an integrative approach to answer these questions with genomic sequencing and paleo-species distribution modeling. Here, we tested the predictions of the classic river, refuge, and river-refuge hypotheses on diversification in the arboreal West and Central African snake genus Toxicodryas. We used dated phylogeographic inferences, population clustering analyses, machine learning-based demographic model selection, species paleo-distribution range estimates, and climate stability modeling to conduct a comprehensive phylogenomic and historical demographic analysis of this genus. Our results revealed significant population genetic structure within both Toxicodryas species, corresponding geographically to river barriers, and divergence times ranging from the mid to late Miocene. Our demographic and migration analyses supported our interpretation that rivers have represented strong barriers to gene flow among populations since their divergence. Additionally, we found no support for a major contraction of suitable habitat during the last glacial maximum, allowing us to reject both the refuge and river-refuge hypotheses in favor of the river barrier hypothesis. This study highlights the complexity of diversification dynamics in the African tropics and the advantage of integrative approaches to studying speciation in tropical regions.

Peer review status:UNDER REVIEW

01 May 2020Submitted to Molecular Ecology
04 May 2020Assigned to Editor
04 May 2020Submission Checks Completed
18 May 2020Reviewer(s) Assigned
05 Jul 2020Review(s) Completed, Editorial Evaluation Pending