From Gondwana to the Yellow Sea, evolutionary diversifications of true toads Bufo sp. in the Eastern Palearctic and a revisit of species boundaries for Asian lineages
Laboratory of Animal Behaviour and Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing, China; Department of Life Sciences and Division of EcoScience, Ewha Womans University, Seoul, Republic of Korea
Spartak N Litvinchuk
Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russian Federation
Irina Maslova
Federal Scientific Center of the East Asia Terrestrial Biodiversity Far Eastern Branch of Russian Academy of Sciences, Vladivostok, Russian Federation
Hollis Dahn
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
Kevin R Messenger
Herpetology and Applied Conservation Laboratory, College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
Desiree Andersen
Department of Life Sciences and Division of EcoScience, Ewha Womans University, Seoul, Republic of Korea
Department of Life Science, Chinese Culture University, Taipei, Taiwan
Yoonhyuk Bae
Department of Life Sciences and Division of EcoScience, Ewha Womans University, Seoul, Republic of Korea
Jennifer Hoti
Department of Life Sciences and Division of EcoScience, Ewha Womans University, Seoul, Republic of Korea; Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
Taxa with vast distribution ranges often display unresolved phylogeographic structures and unclear taxonomic boundaries resulting in hidden diversity. This hypothesis-driven study reveals the evolutionary history of Bufonidae, covering the phylogeographic patterns found in Holarctic bufonids from the West Gondwana to the phylogenetic taxonomy of Asiatic true toads in the Eastern Palearctic. We used an integrative approach relying on fossilized birth-death calibrations, population dynamics, gene-flow, species distribution, and species delimitation modeling to resolve the biogeography of the clade and highlight cryptic lineages. We verified the near-simultaneous Miocene radiations within Western and Eastern Palearctic Bufo, c. 14.49–10.00 Mya, temporally matching with the maximum dust outflows in Central Asian deserts. Contrary to earlier studies, we demonstrated that the combined impacts of long dispersal and ice-age refugia equally contributed to the current genetic structure of Bufo in East Asia. Our findings reveal a climate-driven adaptation in septentrional Eastern Asian Bufo, explaining its range shifts toward northern latitudes. We resolve species boundaries within the Eastern Palearctic Bufo, and redefine the taxonomic and conservation units of the northeastern species: B. sachalinensis and its subspecies.
