Data from: Spatial variation in climate mediates gene flow across an island archipelago

High levels of gene flow among partially isolated populations can overwhelm selection and limit local adaptation. This process, known as “gene swamping,” can homogenize genetic diversity among populations and reduce the capacity of a species to withstand rapid environmental change. We studied brown anole lizards (Anolis sagrei) distributed across seven islands in The Bahamas. We used microsatellite markers to estimate gene flow among islands and then examined the correlation between thermal performance and island temperature. The thermal optimum for sprint performance was correlated with both mean and maximum island temperature whereas performance breadth was not correlated with any measure of temperature variation. Gene flow between islands decreased as the difference between mean island temperatures increased, even when those islands were adjacent to one another. These data suggest that phenotypic variation is the result of either 1) local genetic adaptation with selection against immigrants maintaining variation in the thermal optimum, 2) irreversible forms of adaptive plasticity such that immigrants have reduced fitness, or 3) an interaction between fixed genetic differences and plasticity. In general, the patterns of gene flow we observed suggest that local thermal environments represent important ecological filters that can mediate gene flow on relatively fine geographic scales.部分隔离种群间的高水平基因流（gene flow）可抵消选择压力，限制本地适应过程。这一被称为“基因冲刷（gene swamping）”的过程，会使种群间的遗传多样性趋于同质化，降低物种抵御快速环境变化的能力。本研究以分布于巴哈马7座岛屿的棕安乐蜥（Anolis sagrei）为研究材料，采用微卫星标记（microsatellite markers）估算岛屿间的基因流水平，随后分析了热性能与岛屿温度之间的相关性。疾跑性能的最适温度与岛屿平均温度及最高温度均呈显著相关，而性能广度则与任何温度变异指标均无相关性。即便岛屿彼此相邻，岛屿间的基因流水平仍随岛屿平均温度差值的增大而降低。上述数据表明，表型变异可能源于以下三种机制之一：1）本地遗传适应——通过对迁入个体的选择维持最适温度的变异；2）不可逆转的适应性可塑性，致使迁入个体适合度下降；3）固定遗传差异与可塑性之间的交互作用。总体而言，我们观测到的基因流模式表明，本地热环境是重要的生态过滤因子，可在相对精细的地理尺度上调控基因流水平。