Richardson Jonathan L, Michaelides Sozos, Combs Matthew, Djan Mihajla, Bisch Lianne, Barrett Kerry, Silveira Georgianna, Butler Justin, Aye Than Thar, Munshi-South Jason, DiMatteo Michael, Brown Charles, McGreevy Thomas J
Department of Biology University of Richmond Richmond VA USA.
Department of Natural Resources Science University of Rhode Island Kingston RI USA.
Evol Appl. 2020 Nov 6;14(1):163-177. doi: 10.1111/eva.13133. eCollection 2021 Jan.
As the rate of urbanization continues to increase globally, a growing body of research is emerging that investigates how urbanization shapes the movement-and consequent gene flow-of species in cities. Of particular interest are native species that persist in cities, either as small relict populations or as larger populations of synanthropic species that thrive alongside humans in new urban environments. In this study, we used genomic sequence data (SNPs) and spatially explicit individual-based analyses to directly compare the genetic structure and patterns of gene flow in two small mammals with different dispersal abilities that occupy the same urbanized landscape to evaluate how mobility impacts genetic connectivity. We collected 215 white-footed mice () and 380 big brown bats () across an urban-to-rural gradient within the Providence, Rhode Island (U.S.A.) metropolitan area (population =1,600,000 people). We found that mice and bats exhibit clear differences in their spatial genetic structure that are consistent with their dispersal abilities, with urbanization having a stronger effect on mice. There were sharp breaks in the genetic structure of mice within the Providence urban core, as well as reduced rates of migration and an increase in inbreeding with more urbanization. In contrast, bats showed very weak genetic structuring across the entire study area, suggesting a near-panmictic gene pool likely due to the ability to disperse by flight. Genetic diversity remained stable for both species across the study region. Mice also exhibited a stronger reduction in gene flow between island and mainland populations than bats. This study represents one of the first to directly compare multiple species within the same urban-to-rural landscape gradient, an important gap to fill for urban ecology and evolution. Moreover, here we document the impacts of dispersal capacity on connectivity for native species that have persisted as the urban landscape matrix expands.
随着全球城市化率持续上升，越来越多的研究开始探讨城市化如何塑造城市中物种的移动以及随之而来的基因流动。特别令人感兴趣的是那些在城市中生存下来的本地物种，它们要么以小的残余种群形式存在，要么以在新的城市环境中与人类共生的较大的伴人物种种群形式存在。在本研究中，我们使用基因组序列数据（单核苷酸多态性）和基于个体的空间明确分析，直接比较了两种具有不同扩散能力、占据相同城市化景观的小型哺乳动物的遗传结构和基因流动模式，以评估移动性如何影响遗传连通性。我们在美国罗德岛州普罗维登斯市大都市区（人口 = 160万）的城乡梯度范围内收集了215只白足鼠和380只大棕蝠。我们发现，小鼠和蝙蝠在空间遗传结构上表现出明显差异，这与它们的扩散能力一致，城市化对小鼠的影响更大。在普罗维登斯城市核心区域内，小鼠的遗传结构出现急剧变化，同时迁移率降低，近亲繁殖随着城市化程度的提高而增加。相比之下，蝙蝠在整个研究区域内的遗传结构非常微弱，这表明由于其飞行扩散能力，基因库近乎随机交配。在整个研究区域内，两种物种的遗传多样性都保持稳定。小鼠在岛屿和大陆种群之间的基因流动减少程度也比蝙蝠更强。这项研究是首批直接比较同一城乡景观梯度内多个物种的研究之一，这是城市生态学和进化领域需要填补的一个重要空白。此外，我们在此记录了随着城市景观矩阵的扩展，扩散能力对持续存在的本地物种连通性的影响。
