Data from: Partitioning multiple facets of beta diversity in a tropical stream macroalgal metacommunity

Aim: We evaluated different dimensions of beta diversity (taxonomic,
phylogenetic, and functional), and its components (spatial turnover and
nestedness), of a stream macroalgal metacommunity, as well as the effect
of local environmental variables, types of biome, and spatial factors on
these dimensions and components. Location: Ten natural areas of southern
Brazil, covering the main biomes represented in the region. Methods: We
analyzed a data set collected in 105 stream segments using a dissimilarity
partitioning approach to decompose total beta diversity (beta.SOR –
multisite dissimilarity; beta.sor – pairwise dissimilarity) into spatial
turnover (beta.SIM; beta.sim) and nestedness (beta.SNE; beta.sne)
components. Furthermore, we assessed the effects of local environmental
variables, types of biome, and spatial factors on beta diversity
components by performing distance-based redundancy analysis (db-RDA), and
its partial version (db-pRDA). Taxonomic data were tabulated considering
four different species incidence matrices: total macroalgae; only green
algae; only red algae; and only cyanobacteria. Results: For taxonomic and
phylogenetic dimensions, very high values of total beta diversity
(beta.SOR) were found for all species incidence matrices, with beta.SOR
and spatial turnover (beta.SIM) showing strong correspondence to each
other; nestedness (beta.SNE) had extremely low values. For the functional
dimension, high beta.SOR value and a predominance of beta.SIM over
beta.SNE were also found, but the difference between beta.SIM and beta.SNE
was substantially lower than that observed for taxonomic and phylogenetic
dimensions. In regard to taxonomic and phylogenetic dimensions, total beta
diversity and spatial turnover were, in general, significantly related to
local environmental variables, types of biome, and spatial factors for
total macroalgae and green algae, whereas they were significantly related
to types of biome and space for red algae, and only to local environment
for cyanobacteria. Main conclusions: Our results showed, therefore, that
spatial turnover was the main component of beta diversity regardless of
the dimension and macroalgal species incidence matrix and that the
relative influence of local environmental variables, types of biome, and
spatial factors on the total beta diversity and its spatial turnover
component can vary according to the dimension considered and by algal
group.

研究目的：本研究评估了河流大型藻类元群落（metacommunity）的β多样性（beta diversity）的不同维度——分类学、系统发育学与功能学维度，及其组分——空间周转（spatial turnover）与嵌套性（nestedness），同时探究局域环境变量、生物群区类型与空间因子对这些维度和组分的影响。
研究区域：巴西南部10处自然区域，覆盖该区域内的主要生物群区类型。
研究方法：本研究针对105个河段采集的数据集，采用群落相异性分解（dissimilarity partitioning）方法，将总β多样性[包含多位点相异性指标beta.SOR与成对相异性指标beta.sor]拆解为空间周转组分（beta.SIM与beta.sim）与嵌套性组分（beta.SNE与beta.sne）。此外，本研究通过基于距离的冗余分析（distance-based redundancy analysis, db-RDA）及其偏分析版本（db-pRDA），评估了局域环境变量、生物群区类型与空间因子对β多样性组分的影响。分类学数据按照四类不同的物种出现矩阵（species incidence matrices）进行整理：涵盖所有大型藻类、仅绿藻、仅红藻以及仅蓝细菌（cyanobacteria）。
研究结果：对于分类学与系统发育学维度，所有物种出现矩阵的总β多样性（beta.SOR）均处于极高水平，且beta.SOR与空间周转组分beta.SIM呈现极强的对应关系；嵌套性组分beta.SNE的数值则极低。对于功能学维度，同样观测到较高的beta.SOR值，且beta.SIM占比高于beta.SNE，但二者的差值显著低于分类学与系统发育学维度的结果。就分类学与系统发育学维度而言，总β多样性与空间周转组分总体上与所有大型藻类、绿藻的局域环境变量、生物群区类型及空间因子显著相关；对于红藻，则仅与生物群区类型及空间因子显著相关；而蓝细菌仅与局域环境变量显著相关。
主要结论：综上，本研究结果表明，无论基于何种多样性维度或是哪类大型藻类物种出现矩阵，空间周转均为β多样性的核心组分；同时，局域环境变量、生物群区类型与空间因子对总β多样性及其空间周转组分的相对影响，会因所考虑的多样性维度以及藻类类群的不同而产生差异。