UNCORRECTED PROOF Fungal Ecology xxx (xxxx) xxx-xxx Contents lists available at ScienceDirect Fungal Ecology journal homepage: www.elsevier.com Identifying the mechanisms that shape fungal community and metacommunity patterns in Yunnan, China Kingsly C. Beng a, b, ∗ , Richard T. Corlett a, b a Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China b Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China ARTICLE INFO Article history: Received 21 March 2019 Received in revised form 6 August 2019 Accepted 10 August 2019 Available online xxx Keywords: Metacommunity structure Karst Soil pH Dispersal limitation Environmental filtering Species distribution Trophic guilds Taxonomic groups Tropics Yunnan ABSTRACT Fungi are key organisms in terrestrial ecosystems, functioning as decomposers, pathogens, and symbionts. Identifying the mechanisms that shape metacommunity patterns is likely to be critical for predicting how ecosystems will respond to global environmental change. Using fungal occurrence data and a hierarchical ap- proach that combines three elements of metacommunity structure—coherence, turnover and boundary clump- ing—we identified the structures that best describe metacommunity patterns. We related these patterns to underlying environmental and spatial variables known to influence fungal distribution, and determined the relative importance of the environment and geographic distance in structuring fungal metacommunities. Fun- gal metacommunities had Clementsian and quasi-Clementsian structures, indicating that species distributions were compartmentalized along a dominant environmental gradient. This gradient was strongly associated with annual precipitation, precipitation seasonality and pH for the entire metacommunity. Variance partitioning revealed that the environment was relatively more important than geographic distance in explaining meta- community patterns, indicating that niche-based processes are crucial in shaping species distributions among sites. However, the strength of the relationship between the latent gradient and environmental factors and the relative contributions of the environment and geographic distance to metacommunity structure varied across groups, suggesting that interactions among habitat, dispersal and life-history might be driving these differ- ences. © 2019. 1. Introduction Evolutionary and ecological processes have a major influence on the composition and distribution of biological assemblages, so many plants, animals, fungi and microbes are found only in certain environ- ments, although tight correlations can make it difficult to separate the influence of particular processes. Substantial improvements in meth- ods, concepts and theories have enhanced our understanding of the mechanisms that structure ecological communities and the relative im- portance of the different processes, with a plethora of studies on the niche-based (e.g., environmental filtering) versus neutral (e.g., disper- sal limitation) processes (Dallas, 2014; Caruso et al., 2019; Gibert and Escarguel, 2019). Despite these developments, our understanding of how fungal communities are organized along environmental gradients and how these patterns of spatial variation relate to underlying ecolog- ical processes remains poor, especially in the biodiversity-rich tropics and subtropics (Andrew et al., 2018; Ordynets et al., 2018). ∗ Corresponding author. Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, PR China. Email address: bengkingsly2000@yahoo.com (K.C. Beng) Fungi are key organisms in terrestrial ecosystems, functioning as decomposers, pathogens, and symbionts (Nicolás et al., 2018; Sterkenburg et al., 2018; Zheng et al., 2018), so identifying the mech- anisms that underlie their distributions and the processes that structure their communities is likely to be critical for predicting how ecosys- tems will respond to global environmental change (McGuire et al., 2012; Talbot et al., 2014; Wardle and Lindahl, 2014; Sheldrake et al., 2018; Weiβbecker et al., 2018; Zhang et al., 2018b). Metabarcoding (amplicon-based DNA sequencing of bulk samples) has revolution- ized the acquisition of large-scale information on fungi and the assess- ment of macroecological patterns at local, regional and global scales (Purahong et al., 2017; Alzarhani et al., 2019; Yang et al., 2019). These patterns have been associated with underlying environmental conditions, geographic distance or a combination of both (Peay et al., 2010; Kivlin et al., 2011; Adams et al., 2013; Cline and Zak, 2014; Glassman et al., 2017; Pec et al., 2017), suggesting that the relative importance of niche and neutral processes in structuring fungal com- munities is scale- and context-dependent (Kivlin et al., 2014; Glynou et al., 2017). Soil pH has a major influence on both nutrient supply and the avail- ability of toxic cations, and is often the most important edaphic vari- able influencing soil fungal communities at local and global scales, with some groups showing strong preferences for the extremes of the pH range (Tedersoo et al. 2014, 2017; Glassman et al., 2017). https://doi.org/10.1016/j.funeco.2019.08.006 1754-5048/ © 2019.