Spatial and local environmental factors outweigh geo‐climatic gradients in structuring taxonomically and trait‐based β‐diversity of benthic algae

Abstract

Aim: Understanding the variation in biodiversity and its underlying drivers and mechanisms is a core task in biogeography and ecology. We examined (a) the relative contributions of species replacement (i.e., turnover) and richness difference (i.e., nestedness) to taxonomically and trait-based β-diversity of stream benthic algae; (b) whether these two facets of β-diversity are correlated with each other; and (c) the relative contributions of local environmental, geo-climatic and spatial factors to the two facets of β-diversity and their components. Location: Hun-Tai River Basin, northeastern China. Taxon: Stream benthic algae. Methods: A total of 157 sites were sampled. Mantel tests were used to examine the complementarities between the two facets of β-diversity and their components. Distance-based redundancy analysis and variation partitioning were utilized to investigate the relative contributions of local environmental, geo-climatic and spatial factors to each facet of β-diversity and their components. Results: Weak correlations between taxonomically and trait-based β-diversity and their components were detected, which indicated complementarity of ecological information. Taxonomically based total β-diversity was largely driven by turnover, whereas trait-based total β-diversity was more driven by nestedness. Variation partitioning results indicated that local environmental and spatial factors contributed more than geo-climatic variables to the total explained variation in taxonomically and traitbased β-diversity. Main conclusions: Different facets of β-diversity and their decomposition are important for understanding diversity patterns of benthic algae relative to abiotic factors. A high level of trait-based convergence among benthic algae communities, despite high taxonomic divergence, demonstrated turnover of species with similar biological traits across our study region. Our study provides a trait-based insight into stream benthic algae communities, which was less documented by previous freshwater studies that focused on regions undergoing recovery following human disturbances.| 1843 WU et al.

Environment regimes play an important role in structuring trait‐ and taxonomy‐based temporal beta diversity of riverine diatoms

“…Second, many previous similar studies (e.g. Branco et al, 2020; Ding et al, 2021; López‐Delgado et al, 2020; Perez Rocha et al, 2018; Pozzobom et al, 2021; Wu et al, 2021) have employed db‐RDA, with which our results can be comparable. Therefore, we followed the step‐by‐step procedures devised in previous studies (see also the work flow chart in Appendices S4 and S5).…”

“…At first, we calculated beta diversity and its components (i.e. total, turnover and nestedness) for both facets: (a) taxonomy‐based temporal beta diversity and its components were generated based on presence–absence data (using Sørensen distance); (b) trait‐based temporal beta diversity and its turnover and nestedness components were produced using the 15 traits (using Sørensen distance), following the approach in previous studies (Perez Rocha et al, 2019; Wu et al, 2021). The decomposition of temporal beta diversity allowed us to explore the relative roles of turnover and nestedness components to total trait‐ and taxonomy‐based temporal beta diversity ( question i ).…”

“…Results from VPA were shown by Venn diagrams, which is a standard way to show the fractions explained purely by each dataset as well as by their intersections (e.g. López‐Delgado et al, 2020; Perez Rocha et al, 2018; Wu et al, 2021).…”

“…As an important primary producer in aquatic ecosystems, diatoms were increasingly involved as environmental indicators in freshwater ecosystems due to their well‐known distinct features (Wijewardene et al, 2021; Wu et al, 2017). Consequently, diatom‐based biodiversity studies have been widely carried out around the world (Benito et al, 2018; Branco et al, 2020; Leboucher et al, 2019; Wu et al, 2021). However, most of these studies used only taxonomic composition, which was highly influenced by micro‐evolutionary processes and less suitable for large spatial and temporal scale studies of environmental changes (Soininen et al, 2016).…”

“…At the meanwhile, several trait categories have been proposed and implemented recently, such as diatom guilds, biovolumes and life‐forms (Lange et al, 2016; Passy, 2007; Rimet & Bouchez, 2012; Witteveen et al, 2020). Nevertheless, most investigations that studied beta diversity of riverine diatoms usually highlighted taxonomic composition, while comparisons among different facets of beta diversity and their relationship to multiple environmental stressors were still scarce (but see Branco et al, 2020, Jamoneau et al, 2018, Perez Rocha et al, 2019, Wu et al, 2021). To our best knowledge, no study has focused on temporal beta diversity patterns of riverine diatoms with consideration of both taxonomy and functional trait yet.…”