Landscape heterogeneity can shape genetic structure and functional connectivity of populations. When this heterogeneity imposes variable costs of moving across the landscape, populations can be structured according to a pattern of “isolation by resistance” (IBR). At the same time, divergent local environmental filters can limit gene flow, creating an alternative pattern of “isolation by environment” (IBE). Here, we evaluate IBR and IBE in the insect‐pollinated, biennial plant Sabatia angularis (L.) Pursh (Gentianaceae) across serpentine grasslands in the fragmented landscape of SE Pennsylvania, USA using ~4500 neutral SNP loci. Specifically, we test the extent to which radical alteration of the landscape matrix by humans has fundamentally altered the cost of movement, imprinting a pattern of IBR dictated by land use type and intensity, and the potential for IBE in relation to a gradient of heavy metal concentrations found in serpentine soil. We reveal a strong signal of IBR and a weak signal of IBE across sites, indicating the greater importance of the landscape matrix in shaping genetic structure of S. angularis populations in the study region. Based on Circuitscape and least cost path approaches, we find that both low‐ and high‐intensity urbanization resist gene flow by orders of magnitude greater than “natural” habitats, although resistance to low‐intensity urbanization weakens at larger spatial scales. While cropland presents a substantially lower barrier than urban development, cumulative human land use surrounding populations predicts within‐population genetic diversity and inbreeding in S. angularis. Our results emphasize the role of forest buffers and corridors in facilitating gene flow between serpentine grassland patches and averting local extinction of plant populations.

中文翻译：

---

周围人类土地利用的类型和强度，而不是当地环境，塑造了原生草原植物的遗传结构

景观异质性可以塑造种群的遗传结构和功能连通性。当这种异质性强加了穿越景观的可变成本时，可以根据“抵抗隔离”（IBR）的模式来构造种群。同时，不同的局部环境过滤器可以限制基因流动，创造一种“环境隔离”（IBE）的替代模式。在这里，我们评估了昆虫授粉的二年生植物Sabatia angularis中的 IBR 和 IBE（L.）Pursh（龙胆科）在美国宾夕法尼亚州东南部支离破碎的景观中使用约 4500 个中性 SNP 位点穿过蛇纹石草原。具体来说，我们测试了人类对景观矩阵的彻底改变在多大程度上从根本上改变了移动成本，印记了由土地利用类型和强度决定的 IBR 模式，以及 IBE 与重金属梯度相关的潜力在蛇纹石土壤中发现的浓度。我们揭示了 IBR 的强信号和 IBE 跨站点的弱信号，表明景观矩阵在塑造S遗传结构中的更大重要性。 棱角分明研究区域的人口。基于Circuitscape和最低成本路径方法，我们发现低强度和高强度城市化对基因流动的抵抗力比“自然”栖息地大几个数量级，尽管对低强度城市化的抵抗力在更大的空间尺度上减弱。虽然农田的障碍远低于城市发展，但周边人口的累积人类土地利用预测S的种群内遗传多样性和近亲繁殖。 棱角分明。我们的研究结果强调了森林缓冲区和走廊在促进蛇纹草原斑块之间的基因流动和避免植物种群局部灭绝方面的作用。