Department of Natural Sciences, Baruch College, City University of New York (CUNY), 17 Lexington Avenue, New York, NY 10010, USA.
Mol Ecol. 2012 Mar;21(6):1360-78. doi: 10.1111/j.1365-294X.2012.05476.x. Epub 2012 Feb 9.
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 parklands. Parks in the urban core are often highly fragmented, leading to rapid genetic differentiation of relatively nonvagile species. However, a diverse array of 'green' spaces may provide dispersal corridors through 'grey' urban infrastructure. I identify urban landscape features that promote genetic connectivity in an urban environment and compare the success of two different landscape connectivity approaches at explaining gene flow. Gene flow was associated with 'effective distances' between populations that were calculated based on per cent tree canopy cover using two different approaches: (i) isolation by effective distance (IED) that calculates the single best pathway to minimize passage through high-resistance (i.e. low canopy cover) areas, and (ii) isolation by resistance (IBR), an implementation of circuit theory that identifies all low-resistance paths through the landscape. IBR, but not IED, models were significantly associated with three measures of gene flow (Nm from F(ST) , BayesAss+ and Migrate-n) after factoring out the influence of isolation by distance using partial Mantel tests. Predicted corridors for gene flow between city parks were largely narrow, linear parklands or vegetated spaces that are not managed for wildlife, such as cemeteries and roadway medians. 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.
在本研究中，我考察了城市树冠覆盖对纽约市公园 15 个白足鼠（Peromyscus leucopus）种群间基因流动的影响。城市核心区的公园通常高度破碎，导致相对非迁徙物种的遗传分化迅速。然而，各种各样的“绿色”空间可能为通过“灰色”城市基础设施的扩散提供走廊。我确定了促进城市环境中遗传连通性的城市景观特征，并比较了两种不同景观连通性方法在解释基因流动方面的成功。基因流动与种群之间的“有效距离”有关，这些距离是根据树冠覆盖率的百分比使用两种不同方法计算得出的：（i）基于有效距离的隔离（IED），它计算出最小化穿过高阻力（即低树冠覆盖率）区域的最佳单一途径，以及（ii）电路理论的隔离阻力（IBR），它确定了景观中所有低阻力路径。在使用部分 Mantel 检验消除距离隔离的影响后，IBR，但不是 IED，模型与三种基因流动指标（Nm 来自 F(ST)、BayesAss+和 Migrate-n）显著相关。城市公园之间基因流动的预测走廊主要是狭窄的、线性的公园或未为野生动物管理的植被空间，例如公墓和道路中央分隔带。这些结果对于理解城市化趋势对本地野生动物的影响以及旨在改善城市生态系统过程的城市重新造林工作具有重要意义。
