Data from: 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

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.研究目的：本研究旨在阐明岛屿群岛系统中边缘特有脊椎动物评估所面临的重大保护挑战，并实证评估跨政治与生物地理边界开展保护遗传学研究的方法复杂性；同时，针对具有高度保护关注度的物种界定问题涉及生物地理分布边缘的岛屿特有类群的情况，论证开展国际协作与统筹的迫切必要性。 研究区域：东南亚、中国台湾兰屿岛及菲律宾。 研究方法：本研究采集了东南亚地区民都洛壁虎-菊池壁虎（Gekko mindorensis-G. kikuchii）物种复合群的遗传样本，并对1个线粒体基因与5个核基因座进行测序。我们采用最大似然法、贝叶斯系统发育分析方法，以及基于溯祖的物种界定分析，以估算系统地理关系、构建多位点单倍型网络，并检验推定的物种边界。 研究结果：系统发育与群体遗传学分析表明，菊池壁虎可能是分布于菲律宾北部至中国台湾的广布物种的边缘种群。但本研究发现，基于等位基因频率的物种界定方法与纳入进化历史的溯祖分析方法所得到的物种边界推论存在差异。基于溯祖的分析结果提示，菊池壁虎或许是一个独立的进化支系。本研究强调，在对广布物种开展保护遗传学评估时，需将溯祖分析方法与群体遗传学方法结合使用。 主要结论：本研究与近期少量相关研究共同表明，兰屿岛（乃至更大范围的台湾地区）动物区系中源自菲律宾的异常类群值得重新审慎审视。未来针对这一鲜被关注的生物地理关系开展的研究，应聚焦于厘清这些类群究竟是近期人类介导的引入物种，还是（可能更古老的）自然扩散的结果。分布于生物地理与政治区域外围岛屿的孤立特有物种，面临着特殊的保护挑战；当某一物种所在的孤立岛屿在生物地理上归属于某一国家，但政治上却由另一国家管辖时，这一挑战尤为突出。