AN ADAPTIVE RADIATION OF FROGS IN A SOUTHEAST ASIAN ISLAND ARCHIPELAGO

Authors

  • David C. Blackburn,

    1. Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, Kansas
    2. Current address: Department of Vertebrate Zoology and Anthropology, California Academy of Sciences, San Francisco, California
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  • Cameron D. Siler,

    1. Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, Kansas
    2. Section of Integrative Biology, University of Texas and Texas Natural Science Center, Austin, Texas
    3. Current address: Department of Biology, University of Oklahoma, Norman, Oklahoma
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  • Arvin C. Diesmos,

    1. Herpetology Section, Zoology Division, National Museum of the Philippines, Padre Burgos Avenue, Ermita 1000, Manila, Philippines
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  • Jimmy A. McGuire,

    1. Department of Integrative Biology, University of California, Berkeley, California
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  • David C. Cannatella,

    1. Section of Integrative Biology, University of Texas and Texas Natural Science Center, Austin, Texas
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  • Rafe M. Brown

    1. Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, Kansas
    2. Section of Integrative Biology, University of Texas and Texas Natural Science Center, Austin, Texas
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Abstract

Living amphibians exhibit a diversity of ecologies, life histories, and species-rich lineages that offers opportunities for studies of adaptive radiation. We characterize a diverse clade of frogs (Kaloula, Microhylidae) in the Philippine island archipelago as an example of an adaptive radiation into three primary habitat specialists or ecotypes. We use a novel phylogenetic estimate for this clade to evaluate the tempo of lineage accumulation and morphological diversification. Because species-level phylogenetic estimates for Philippine Kaloula are lacking, we employ dense population sampling to determine the appropriate evolutionary lineages for diversification analyses. We explicitly take phylogenetic uncertainty into account when calculating diversification and disparification statistics and fitting models of diversification. Following dispersal to the Philippines from Southeast Asia, Kaloula radiated rapidly into several well-supported clades. Morphological variation within Kaloula is partly explained by ecotype and accumulated at high levels during this radiation, including within ecotypes. We pinpoint an axis of morphospace related directly to climbing and digging behaviors and find patterns of phenotypic evolution suggestive of ecological opportunity with partitioning into distinct habitat specialists. We conclude by discussing the components of phenotypic diversity that are likely important in amphibian adaptive radiations.

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