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Rivers, not refugia, drove diversification in arboreal, sub-Saharan African snakes
Allen, Kaitlin E. Greenbaum, Eli Hime, Paul M. Tapondjou N., Walter P. Sterkhova, Viktoria V. Kusamba, Chifundera Rödel, Mark-Oliver Penner, Johannes Peterson, A. Townsend Brown, Rafe M.
Allen, Kaitlin E.
Greenbaum, Eli
Hime, Paul M.
Tapondjou N., Walter P.
Sterkhova, Viktoria V.
Kusamba, Chifundera
Rödel, Mark-Oliver
Penner, Johannes
Peterson, A. Townsend
Brown, Rafe M.
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Abstract
The relative roles of rivers versus refugia in shaping the high levels of species diversity in tropical rainforests have been widely debated for decades. Only recently has it become possible to take an integrative approach to test predictions derived from these hypotheses using genomic sequencing and paleo-species distribution modeling. Herein, we tested the predictions of the classic river, refuge, and river-refuge hypotheses on diversification in the arboreal sub-Saharan African snake genus Toxicodryas. We used dated phylogeographic inferences, population clustering analyses, demographic model selection, and paleo-distribution modeling to conduct a 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 from the mid-Miocene to Pliocene. Our demographic analyses supported the interpretation that rivers are indications of 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. Based on conservative interpretations of our species delimitation analyses with the Sanger and ddRAD data sets, two new cryptic species are identified from east-central Africa. This study highlights the complexity of diversification dynamics in the African tropics and the advantages of integrative approaches to studying speciation in tropical regions.
Description
A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.
Date
2021-05-01
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Wiley Open Access
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Keywords
Historical demography, Machine learning, Paleo-distributions, Phylogenomics, Toxicodryas
Citation
Allen, KE, Greenbaum, E, Hime, PM, et al. Rivers, not refugia, drove diversification in arboreal, sub-Saharan African snakes. Ecol Evol. 2021; 11: 6133– 6152. https://doi.org/10.1002/ece3.7429