Aim: The abundance–frequency relationship (AFR) is among the most-investigated patterns in biogeography, yet the relative contributions of niche-based processes related to ecological strategies, and of neutral processes related to spatial colonization– extinction dynamics, remains uncertain. Here, we tested the influences of ecological specialization and functional traits on local abundance and regional frequency, to determine the contribution of niche-based processes. Location: France and the UK. Taxon: Vascular plants. Methods: We used two arable weed surveys covering 1,544 fields in Western Europe (France, UK), along with functional traits related to resource acquisition, resource requirements, flowering phenology and dispersal. We quantified specialization both to arable habitat and to individual crop types, and performed phylogenetic path analyses to test competing models accounting for direct and indirect relationships between traits, specialization, abundance and frequency. We performed the analyses for all species in each country, as well as for a subset of the most abundant species. Results: Local abundance of weeds increased with their regional frequency, but the relationship became negative or null when considering only the most abundant weeds. Specialization to arable habitat and to individual crop type either had a similar or opposite effect on regional frequency and local abundance explaining these positive and negative relationships, respectively. Regional frequency was not directly explained by any trait but indirectly by resource requirement traits conferring specialization to the arable habitat. Conversely, high local abundance was directly related to low seed mass, high SLA, early and short flowering. Main conclusions: Direct/indirect effects of functional traits on local abundance/regional frequency, respectively, supports a significant role of niche-based processes in AFR. Neutral spillover dynamics could further explain a direct linkage of abundance and frequency. Similar causal paths and consistent influences of traits on specialization and abundance in the two studied regions suggest genericity of these findings.

中文翻译：

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生态专业化和功能特征是否可以解释丰度-频率关系？以耕地杂草为例

目标：丰度-频率关系 (AFR) 是生物地理学中研究最多的模式之一，但与生态战略相关的基于生态位的过程以及与空间殖民-灭绝动态相关的中性过程的相对贡献仍然不确定。在这里，我们测试了生态专业化和功能特征对当地丰度和区域频率的影响，以确定基于生态位的过程的贡献。地点：法国和英国。分类群：维管植物。方法：我们使用了两项涵盖西欧（法国、英国）1,544 个田地的耕地杂草调查，以及与资源获取、资源需求、开花物候和传播相关的功能特征。我们量化了耕地栖息地和个别作物类型的专业化，并进行了系统发育路径分析，以测试解释性状、专业化、丰度和频率之间直接和间接关系的竞争模型。我们对每个国家的所有物种以及最丰富物种的一个子集进行了分析。结果：杂草的局部丰度随着其区域频率的增加而增加，但当仅考虑最丰富的杂草时，这种关系变为负数或无效。对可耕地栖息地和个体作物类型的专业化对区域频率和当地丰度有相似或相反的影响，分别解释了这些正负关系。区域频率不是由任何性状直接解释的，而是由赋予耕地栖息地专业化的资源需求性状间接解释的。反过来，高局部丰度与低种子质量、高SLA、早花和短花直接相关。主要结论：功能性状对局部丰度/区域频率的直接/间接影响分别支持基于生态位的过程在 AFR 中的重要作用。中性溢出动态可以进一步解释丰度和频率的直接联系。相似的因果路径和特征对两个研究区域的专业化和丰度的一致影响表明这些发现具有普遍性。