Landscape genetics of the western fence lizard (Sceloporus occidentalis becki) on Santa Cruz Island: the role of habitat complexity and climate on genetic connectivity of populations across the island.

The California Channel Islands is home to several endemic species and sub-species of amphibians and reptiles, yet comprehensive studies of the genetic relationships of Channel Island reptile species has yet to be done. We propose to examine the landscape genetic structure of Sceloporus occidental becki on Santa Cruz Island (California Channel Islands National Park). Landscape genetics seeks to understand the role of environmental variables (habitat and climate) on the genetic connectivity of populations. Santa Cruz Island is the ideal setting for a landscape study, due to the rich biome diversity and dramatic topographic relief. In addition to the biome diversity on the island, there are substantial climatic differences across the island, resulting in hot and dry habitats on the western part of the island, and cool and wet habitat on the eastern side of the mountain. These differences in habitat and climate could influence the fine-scale connectivity of populations. This research will examine the role of habitat and climate as important mediating factors that limit gene flow across the island. We predict that both habitat and climate variation are important features that structure populations, but our landscape models are required to identify the specific variables that play the most significant role. Current genetic analyses might reveal that the western fence lizard is an island endemic. If so, then our landscape genetics study, which seeks to understand the factors most important for the maintaining the evolutionary relationships among populations on the island, becomes a conservation imperative.加利福尼亚海峡群岛（California Channel Islands）孕育了诸多两栖类与爬行类的特有物种及亚种，但目前仍未开展针对该群岛爬行类物种遗传关系的系统性研究。本研究拟对坐落于加利福尼亚海峡群岛国家公园（California Channel Islands National Park）的圣克鲁斯岛（Santa Cruz Island）上的西部栅栏蜥蜴贝克亚种（Sceloporus occidentalis becki，原文作Sceloporus occidental becki）开展景观遗传学（Landscape Genetics）结构解析。景观遗传学旨在探明环境变量（栖息地与气候）对种群遗传连通性的调控作用。圣克鲁斯岛兼具丰富的生物群系多样性与显著的地形起伏，是开展景观遗传学研究的理想载体。除却生物群系多样性，岛内还存在显著的气候分异：岛西侧为炎热干燥的生境，山地东侧则为凉爽湿润的生境。这类生境与气候差异可能会影响种群的精细尺度遗传连通性。本研究将厘清生境与气候作为限制岛内种群间基因流的关键介导因子的作用机制。我们预测生境与气候变异均为塑造种群结构的重要特征，但需借助景观遗传学模型才能明确其中发挥核心调控作用的具体变量。现有遗传分析或可表明，西部栅栏蜥蜴（western fence lizard）为该岛特有物种。若此结论成立，这项旨在解析岛内种群间进化关系关键影响因子的景观遗传学研究，将具备明确的保护紧迫性。