Data from: Urban landscape genetics: canopy cover predicts gene flow between white-footed mouse (Peromyscus leucopus) populations in New York City

In this study, I examine the influence of urban canopy cover on gene flow between 15 white-footed mouse (Peromyscus leucopus) populations in New York City. Nm calculated from F_ST and recent migration estimated in BayesAss+, but not historic migration estimated in Migrate-n, exhibited significant isolation-by-distance (IBD). Gene flow was also associated with “effective distances” between populations that were calculated based on percent canopy cover using two different approaches: 1) isolation-by-effective-distance (IED) that calculates the single best pathway to minimize passage through high-resistance (i.e. low canopy cover) areas, and 2) isolation-by-resistance (IBR), an implementation of circuit theory that identifies all low-resistance paths through the landscape. IBR, but not IED, models were still significantly associated with all three measures of gene flow after factoring out the influence of IBD using partial Mantel tests. In cases where both IBR and IED explained gene flow independently of IBD, an additional partial Mantel test indicated that the IBR models still explained gene flow after factoring out IED. The IBR models that explained the most variation in recent migration after factoring out IBD (r = 0.70 – 0.90) included landscape cells with at least 60-80% canopy cover as low resistance habitat. These results have implications for understanding the impacts of urbanization trends on native wildlife, as well as for urban reforestation efforts that aim to improve urban ecosystem processes.

本研究探究了城市冠层覆盖度对纽约市15个白足鼠（Peromyscus leucopus）种群间基因流的影响。基于F_ST计算得到的Nm值以及通过BayesAss+软件估算的近期迁移事件，但并非通过Migrate-n软件估算的历史迁移事件，均表现出显著的距离隔离（isolation-by-distance, IBD）效应。种群间的基因流还与基于冠层覆盖百分比通过两种不同方法计算得到的“有效距离”相关：1）有效距离隔离（isolation-by-effective-distance, IED）：该方法计算单条最优路径以最大程度减少穿过高阻力（即低冠层覆盖度）区域的距离；2）阻力隔离（isolation-by-resistance, IBR）：该方法基于电路理论实现，可识别景观中所有低阻力路径。通过部分曼特尔检验排除距离隔离效应的影响后，仅阻力隔离模型而非有效距离隔离模型，仍与所有三项基因流指标呈现显著相关性。当阻力隔离与有效距离隔离均能独立于距离隔离解释基因流时，额外的部分曼特尔检验结果显示，在排除有效距离隔离的影响后，阻力隔离模型仍能解释基因流。在排除距离隔离效应后，对近期迁移事件变异解释度最高的阻力隔离模型（相关系数r=0.70~0.90），将冠层覆盖度至少为60%~80%的景观单元定义为低阻力生境。本研究结果有助于理解城市化进程对本土野生动物的影响，同时也为旨在改善城市生态系统功能的城市再造林工作提供了理论参考。