Disentangling the mechanisms behind indirect interactions between plants via shared pollinators: Effects of neutral and niche‐based processes

Abstract Indirect interactions between plants via shared pollinators play a crucial role in structuring and stabilizing ecological communities. Although both neutral (interactions occurring in proportion to species abundance) and niche‐based (involving morphological matching and phenological overlap) processes are known to structure plant–pollinator interactions, how these processes drive the formation and maintenance of indirect interactions between plants in pollination networks remains poorly understood. Here, we investigated a species‐rich alpine meadow in southwest China to disentangle the potential mechanisms underlying indirect interactions between plants via shared pollinators. We analysed data from the plant–Hymenoptera network, the plant–Diptera network and the whole network combining all plants and pollinators to (1) quantify the prevalence of indirect interactions between plants and their contribution to network structure; (2) assess how plant traits related to neutral (flower abundance) and niche‐based (flower phenology, morphology and phylogeny) processes influence indirect interactions between plants; (3) evaluate the extent to which indirect interactions between plants could be predicted by neutral and niche‐based processes. We found that indirect interactions between plants were highly prevalent across all networks and were related to increased contribution to nestedness, an important structure for network stability and the maintenance of species diversity. Corolla‐tube length dissimilarity was the primary driver of the probability of indirect interactions between plants in both the whole network and the plant–Hymenoptera network, while flowering length had the greatest influence in the plant–Diptera network. Across all networks, flower abundance emerged as the key factor determining the strength of these interactions. Moreover, neutral and niche‐based processes effectively predicted indirect interactions between plants, with neutral processes showing stronger predictive performance than the others. Synthesis . Overall, our study quantifies the prevalence of indirect interactions between plants in pollination networks and their influence on network structure and systematically elucidates the potential mechanisms underlying these interactions. These findings offer new insights into the ecological processes that govern species coexistence and contribute to the maintenance of biodiversity in plant–pollinator communities. 摘要植物通过共享传粉者产生的间接相互作用在生态群落的结构形成和稳定中发挥着关键作用。尽管已知中性过程(互动发生频率与物种丰度成比例)和生态位过程(包括植物与传粉者间的形态匹配和物候重叠)在塑造植物‐传粉者相互作用中具有重要作用,但这些过程如何促进植物间间接相互作用的形成与维持仍知之甚少。在本研究中,我们调查了中国西南部一个物种丰富的高山草甸,以解析通过共享传粉者形成的植物间间接相互作用的潜在机制。我们分析了植物‐膜翅目网络、植物‐双翅目网络以及包含所有植物和传粉者的整体网络,以(1)量化植物间间接相互作用的普遍性及其对网络结构的贡献;(2)评估与中性过程(花丰度)和生态位过程(开花物候、形态及系统发育)相关的植物性状如何影响植物间间接相互作用;(3)评估中性和生态位过程在多大程度上能够预测植物间间接相互作用。结果表明,植物间间接相互作用在所有网络中都高度普遍,并与对网络嵌套性(网络稳定性和物种多样性维持的重要结构)的贡献增加相关。在整体网络和植物‐膜翅目网络中,花冠管长度差异是决定植物间间接相互作用概率的主要因素,而在植物‐双翅目网络中,花期长度的影响最大。在所有网络中,花丰度是决定这些相互作用强度的关键因素。此外,中性和生态位过程都能够有效预测植物间间接相互作用,其中中性过程显示出更强的预测性能。总体而言,我们的研究量化了传粉网络中植物间间接相互作用的普遍性及其对网络结构的影响,并系统阐明了这些作用背后的潜在机制。这些发现为理解调控物种共存的生态过程以及植物‐传粉者群落中生物多样性的维持提供了新的见解。