Data from: Habitat disturbance selects against both small and large species across varying climates

Global extinction drivers, including habitat disturbance and climate change, are thought to affect larger species more than smaller species. However, it is unclear if such drivers interact to affect assemblage body size distributions. We asked how these two key global change drivers differentially affect the interspecific size distributions of ants, one of the most abundant and ubiquitous animal groups on earth. We also asked whether there is evidence of synergistic interactions and whether effects are related to species’ trophic roles. We generated a global dataset on ant body size from 333 local ant assemblages collected by the authors across a broad range of climates and in disturbed and undisturbed habitats. We used head length (range: 0.22 – 4.55 mm) as a surrogate of body size and classified species to trophic groups. We used generalized linear models to test whether body size distributions changed with climate and disturbance, independent of species richness. Our analysis yielded three key results: 1) climate and disturbance showed independent associations with body size; 2) assemblages included more small species in warmer climates and fewer large species in wet climates; and 3) both the largest and smallest species were absent from disturbed ecosystems, with predators most affected in both cases. Our results indicate that temperature, precipitation and disturbance have differing effects on the body size distributions of local communities, with no evidence of synergistic interactions. Further, both large and small predators may be vulnerable to global change, particularly through habitat disturbance.

全球灭绝驱动因子（global extinction drivers），包括生境干扰（habitat disturbance）与气候变化（climate change），被认为对大型物种的影响甚于小型物种。然而目前尚不清楚这些驱动因子是否会通过交互作用影响群落体型分布（assemblage body size distributions）。本研究针对这两类关键全球变化驱动因子如何差异化影响蚂蚁（ant）——地球上最为丰富且分布最广的动物类群之一——的种间体型分布（interspecific size distributions）展开探究，同时亦探究是否存在协同交互作用的证据，以及其影响是否与物种的营养角色（trophic roles）相关。本研究由作者团队在涵盖多样气候类型的受干扰与未受干扰生境（disturbed and undisturbed habitats）中，采集了333个本地蚂蚁群落（local ant assemblages）的数据，进而构建了全球蚂蚁体型数据集。本研究以头长（head length）作为体型的替代指标（surrogate of body size），其范围为0.22–4.55 mm，并将物种划分为不同营养类群（trophic groups）。本研究采用广义线性模型（generalized linear models, GLM），检验在不受物种丰富度（species richness）影响的前提下，体型分布是否会随气候与干扰程度发生变化。本研究分析得到三项核心结果：1）气候与干扰对蚂蚁体型存在独立的关联效应；2）气候越温暖，群落中小型物种占比越高；而气候越湿润，群落中大型物种占比越低；3）受干扰生态系统中既缺乏最大型物种，也缺乏最小型物种，且捕食者（predators）在这两类物种的缺失中受影响最为显著。本研究结果表明，温度、降水与干扰对本地群落的体型分布具有差异化影响，未发现存在协同交互作用的证据。此外，无论大型还是小型捕食者，均可能受到全球变化的威胁，其中生境干扰的影响尤为突出。