Type and intensity of surrounding human land use, not local environment, shape genetic structure of a native grassland plant
Type and intensity of surrounding human land use, not local environment, shape genetic structure of a native grassland plant
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DOI：
10.1111/mec.15753
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发表时间：
2021-01-12
影响因子：
4.9
通讯作者：
Spigler, Rachel B.
中科院分区：
文献类型：
--
作者：
Emel, Sarah L.;Wang, Shichen;Spigler, Rachel B.
景观异质性可以塑造种群的遗传结构和功能连通性。当这种异质性造成在景观中迁移的可变成本时，可以根据“阻力隔离”（IBR）模式来构建种群。同时，不同的局部环境过滤器可以限制基因流动，形成另一种“环境隔离”模式（IBE）。本文对昆虫传粉的二年生植物沙巴提亚（Sabatia angularis， L.）的IBR和IBE进行了研究。利用4500个中性SNP位点对美国宾夕法尼亚州东南部破碎景观蛇形草地上的Pursh （Gentianaceae）进行了研究。具体来说，我们测试了人类对景观基质的彻底改变在多大程度上从根本上改变了迁移成本，印记了由土地利用类型和强度决定的IBR模式，以及与蛇形土壤中重金属浓度梯度相关的IBE潜力。结果表明，景观基质在研究区角蒿种群遗传结构的形成中具有较强的IBR信号和较弱的IBE信号。基于电路景观（Circuitscape）和最小成本路径（least cost path）方法，我们发现低强度和高强度城市化对基因流动的抵抗都比“自然”栖息地大几个数量级，尽管对低强度城市化的抵抗在更大的空间尺度上减弱。与城市发展相比，耕地的障碍要低得多，但人类对种群周围土地的累积利用可以预测角蒿种群内的遗传多样性和近交。我们的研究结果强调了森林缓冲带和廊道在促进蛇形草地斑块之间的基因流动和避免局部植物种群灭绝方面的作用。
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 similar to 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.