目标:尽管对全球生物多样性的模式进行了充分的研究,关于潜在的机制及其在生物地理尺度上的普遍性,仍然存在有争议的争论。特别是,目前还不清楚沿环境梯度的多样性模式在多大程度上是由非生物因素直接驱动的,如气候,或通过生物因子间接介导,比如资源对消费者的影响。
方法:安第斯,厄瓜多尔南部;山。乞力马扎罗山,坦桑尼亚。
方法:我们在分类学水平上研究了肉果植物和禽类食肉动物的多样性,也就是说,物种丰富度和丰度,以及在功能特征层面,也就是说,功能丰富和功能分散。我们比较了新热带地区和非洲热带地区山区系统中两个重要的生物多样性热点。我们使用了植物和鸟类群落的野外数据,包括367种植物和鸟类的性状测量。使用结构方程模型,我们解开了气候和植物群落多样性对鸟类群落多样性的直接和间接影响。
结果:我们在分类水平上发现了水果多样性对水果多样性的显着自下而上的影响。相比之下,气候对于功能多样性的模式更重要,植物群落主要与降水有关,鸟类群落与温度密切相关。
结论:我们的结果说明了自下而上的机制对消费者分类多样性的普遍重要性,表明了主动资源跟踪的重要性。我们的结果还表明,可能很难识别跨生物地理区域的功能性植物和动物性状之间的生态拟合信号,因为不同的物种群体可能对不同的气候驱动因素做出反应。在未来的气候变化下,如果动植物群落始终与不同的气候驱动因素相关,资源和消费者群落之间的这种脱钩可能会增加。
OBJECTIVE: Although patterns of biodiversity across the globe are well studied, there is still a controversial debate about the underlying mechanisms and their generality across biogeographic scales. In particular, it is unclear to what extent diversity patterns along environmental gradients are directly driven by abiotic factors, such as climate, or indirectly mediated through biotic factors, such as resource effects on consumers.
METHODS: Andes, Southern Ecuador; Mt. Kilimanjaro, Tanzania.
METHODS: We studied the diversity of fleshy-fruited plants and avian frugivores at the taxonomic level, that is, species richness and abundance, as well as at the level of functional traits, that is, functional richness and functional dispersion. We compared two important biodiversity hotspots in mountain systems of the Neotropics and Afrotropics. We used field data of plant and bird communities, including trait measurements of 367 plant and bird species. Using structural equation modeling, we disentangled direct and indirect effects of climate and the diversity of plant communities on the diversity of bird communities.
RESULTS: We found significant bottom-up effects of fruit diversity on frugivore diversity at the taxonomic level. In contrast, climate was more important for patterns of functional diversity, with plant communities being mostly related to precipitation, and bird communities being most strongly related to temperature.
CONCLUSIONS: Our results illustrate the general importance of bottom-up mechanisms for the taxonomic diversity of consumers, suggesting the importance of active resource tracking. Our results also suggest that it might be difficult to identify signals of ecological fitting between functional plant and animal traits across biogeographic regions, since different species groups may respond to different climatic drivers. This decoupling between resource and consumer communities could increase under future climate change if plant and animal communities are consistently related to distinct climatic drivers.