Fusco Nicole A, Pehek Ellen, Munshi-South Jason
Department of Biology Fordham University Bronx NY USA.
Natural Resources Group New York City Department of Parks & Recreation New York NY USA.
Evol Appl. 2020 Jun 12;14(1):99-116. doi: 10.1111/eva.13025. eCollection 2021 Jan.
Natural landscape heterogeneity and barriers resulting from urbanization can reduce genetic connectivity between populations. The evolutionary, demographic, and ecological effects of reduced connectivity may lead to population isolation and ultimately extinction. Alteration to the terrestrial and aquatic environment caused by urban influence can affect gene flow, specifically for stream salamanders who depend on both landscapes for survival and reproduction. To examine how urbanization affects a relatively common stream salamander species, we compared genetic connectivity of (northern two-lined salamander) populations within and between streams in an urban, suburban, and rural habitat around the New York City (NYC) metropolitan area. We report reduced genetic connectivity between streams within the urban landscape found to correspond with potential barriers to gene flow, that is, areas with more dense urbanization (roadways, industrial buildings, and residential housing). The suburban populations also exhibited areas of reduced connectivity correlated with areas of greater human land use and greater connectivity within a preserve protected from development. Connectivity was relatively high among neighboring rural streams, but a major roadway corresponded with genetic breaks even though the habitat contained more connected green space overall. Despite greater human disturbance across the landscape, urban and suburban salamander populations maintained comparable levels of genetic diversity to their rural counterparts. Yet small effective population size in the urban habitats yielded a high probability of loss of heterozygosity due to genetic drift in the future. In conclusion, urbanization impacted connectivity among stream salamander populations where its continual influence may eventually hinder population persistence for this native species in urban habitats.
城市化导致的自然景观异质性和障碍会降低种群之间的基因连通性。连通性降低所产生的进化、种群统计学和生态效应可能导致种群隔离并最终灭绝。城市影响造成的陆地和水生环境变化会影响基因流动，对于那些依赖陆地和水域景观进行生存和繁殖的溪流蝾螈来说尤其如此。为了研究城市化如何影响一种相对常见的溪流蝾螈物种，我们比较了纽约市（NYC）大都市区城市、郊区和农村栖息地内溪流之间以及溪流内部（北方双线蝾螈）种群的基因连通性。我们报告称，在城市景观中，溪流之间的基因连通性降低，发现这与基因流动的潜在障碍相对应，即城市化程度更高的区域（道路、工业建筑和住宅）。郊区种群也表现出连通性降低的区域，这些区域与人类土地利用程度较高的区域相关，并且在一个受保护不被开发的保护区内连通性较高。相邻农村溪流之间的连通性相对较高，但一条主要道路与基因间断相对应，尽管栖息地总体上包含更多连通的绿地。尽管整个景观受到更大的人类干扰，但城市和郊区的蝾螈种群与农村蝾螈种群保持了相当的遗传多样性水平。然而，城市栖息地中较小的有效种群规模使得未来由于遗传漂变导致杂合性丧失的可能性很高。总之，城市化影响了溪流蝾螈种群之间的连通性，其持续影响最终可能会阻碍该本地物种在城市栖息地的种群持久性。
