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Critically endangered island endemic or peripheral population of a widespread species? Conservation genetics of Kikuchi's gecko and the global challenge of protecting peripheral oceanic island endemic vertebrates

Authors

  • Cameron D. Siler,

    Corresponding author
    1. Sam Noble Oklahoma Museum of Natural History & Department of Biology, University of Oklahoma, Norman, OK, USA
    2. Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA
    • Correspondence: Cameron D. Siler, Sam Noble Oklahoma Museum of Natural History, University of Oklahoma, 2401 Chautauqua Ave., Norman, OK 73072-7029, USA.

      E-mail: camsiler@ou.edu

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  • Jamie R. Oaks,

    1. Department of Biology, University of Washington, Seattle, WA, USA
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  • Kerry Cobb,

    1. Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA
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  • Hidetoshi Ota,

    1. Institute of Natural and Environmental Sciences, and Museum of Nature and Human Activities, University of Hyogo, Sanda, Hyogo, Japan
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  • Rafe M. Brown

    1. Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA
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Abstract

Aim

To highlight the significant conservation challenge of evaluating peripheral endemic vertebrates in island archipelago systems and to assess empirically the complexities of approaches to conservation genetic studies across political and biogeographic boundaries. To demonstrate the poignant need for international collaboration and coordination when species delimitation problems with high conservation concern involve island endemics with biogeographically peripheral ranges.

Location

Southeast Asia, Lanyu Island, Taiwan, and the Philippines.

Methods

Genetic samples were collected and sequenced for one mitochondrial gene and five nuclear loci for species of the Gekko mindorensis-G. kikuchii species complex in Southeast Asia. We used maximum likelihood and Bayesian phylogenetic methods and coalescent-based species delimitation analyses to estimate phylogeographic relationships, construct multilocus haplotype networks and test putative species boundaries.

Results

Phylogenetic and population genetic analyses suggest that Kikuchi's Gecko may represent a peripheral population of a widespread species distributed from the northern Philippines to Taiwan. However, we identify a discrepancy between inferences of species boundaries resulting from methods based on allele frequencies versus coalescent-based methods that incorporate evolutionary history. Coalescent-based analyses suggest that G. kikuchii may be a distinct evolutionary lineage. Our study underscores the need for coalescent-based methods in conjunction with population genetic approaches for conservation genetic assessments of widespread species.

Main conclusions

This study joins a few recent works suggesting that Philippine-derived anomalies in the fauna of Lanyu (and possibly greater Taiwan) are worthy of careful reconsideration. Determining whether each is the result of recent human-mediated introduction or (possibly more ancient) natural dispersal should be the goal of future studies on this seldom-conceived biogeographic relationship. Isolated species endemic to islands on the outer periphery of biogeographic and political regions represent particular conservation challenges. This is especially true if a species occurs on an isolated island that is allied biogeographically with one nation, but politically administered by another.

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