Institute of Plant Sciences, Altenbergrain 21, 3013, Bern, Switzerland.
Ecology. 2018 Mar;99(3):597-606. doi: 10.1002/ecy.2145.
Understanding why some species are rare while others are common remains a central and fascinating question in ecology. Recently, interactions with soil organisms have been shown to affect local abundances of plant species within communities, however, it is not known whether they might also drive patterns of rarity at large scales. Further, little is known about the specificity of soil-feedback effects, and whether closely related plants share more soil pathogens than more distantly related plants. In a multi-species soil-feedback experiment (using 19 species) we tested whether regionally and locally rare species differed in their response to soil biota. Regional rarity was measured using range size or IUCN status and local rarity by typical abundance within an area. All species were grown on soils trained by a variety of regionally and locally rare and common species, which also varied in their degree of relatedness to the target. We found that, in general, regionally rare species suffered more than twice as much from soil biota than regionally common species. Soil cultured by regionally rare species also had a more negative effect on subsequent plant growth, suggesting they may have also accumulated more pathogens. Local rarity did not predict feedback strength. Further, soil trained by closely related plants had a more negative effect on growth than soil trained by distant relatives, which indicates a phylogenetic signal in the host range of soil biota. We conclude that soil biota may well contribute to plant rarity at large spatial scales, which offers a novel explanation for plant rarity and commonness. Moreover, our results show that phylogenetic relatedness between plants was a good predictor of the likelihood that two plant species interacted negatively via soil biota, which might mean that soil pathogens could prevent the coexistence of closely related plants and could drive patterns of phylogenetic overdispersion. Our results suggest that soil pathogens could restrict the ability of rare species to shift their ranges and might need to be considered by conservation biologists seeking to protect populations of rare plants.
理解为什么有些物种稀有而有些常见仍然是生态学中的一个核心和迷人的问题。最近，与土壤生物的相互作用已被证明会影响群落中植物物种的局部丰度，但是否也会在大尺度上驱动稀有物种的模式尚不清楚。此外，关于土壤反馈效应的特异性，以及密切相关的植物是否比远缘植物分享更多的土壤病原体，人们知之甚少。在一个多物种土壤反馈实验（使用 19 个物种）中，我们测试了区域和局部稀有物种对土壤生物群的反应是否不同。区域稀有性使用范围大小或 IUCN 状态来衡量，局部稀有性使用特定区域内的典型丰度来衡量。所有物种都在经过各种区域和局部稀有和常见物种培养的土壤上生长，这些物种与目标物种的亲缘关系也各不相同。我们发现，一般来说，区域稀有物种受到土壤生物群的影响是区域常见物种的两倍多。由区域稀有物种培养的土壤也对随后的植物生长有更负面的影响，这表明它们可能也积累了更多的病原体。局部稀有性并不能预测反馈强度。此外，亲缘关系较近的植物培养的土壤对生长的负面影响大于亲缘关系较远的植物，这表明土壤生物群在宿主范围上存在系统发育信号。我们的结论是，土壤生物群很可能有助于大空间尺度上的植物稀有性，这为植物稀有性和常见性提供了一个新的解释。此外，我们的结果表明，植物之间的系统发育关系是两种植物通过土壤生物群相互作用的可能性的良好预测指标，这可能意味着土壤病原体可以防止亲缘关系密切的植物共存，并可能驱动系统发育过度分散的模式。我们的研究结果表明，土壤病原体可能会限制稀有物种转移其范围的能力，保护稀有植物种群的保护生物学家可能需要考虑这一点。
