Abstract
AbstractMetacommunity theory provides a framework for assessing the role of spatial and environmental processes in structuring ecological communities and places emphasis on the role of dispersal. Four metacommunity perspectives have been proposed: species‐sorting, patch dynamics, mass effects, and a neutral model. Metacommunity analysis decomposes the variance in communities into regional and local dynamics and ascribes it to one of these perspectives, although they are not always mutually exclusive. Although birds are a well‐studied taxon, consensus around processes structuring freshwater avian metacommunities is lacking and few studies have repeated samples through time. We used variance partitioning to analyze waterbird community data collected over seven sampling periods at 60 wetland sites in KwaZulu‐Natal, South Africa, to distinguish the processes driving beta‐diversity and identify which metacommunity perspective(s) best explained these patterns. We addressed two focal questions: (1) how do environmental, spatial, and spatially structured environmental components contribute to variance in the waterbird community; and (2) given a significant contribution, which environmental variables were most important in explaining metacommunity structure? We also investigated the role of temporal variation in community processes by comparing results across sampling periods. The underlying landscape was characterized by four groups of environmental variables: vegetation structure, water quality, rainfall, and land cover. Moran's eigenvector maps were used to generate a set of multiscale spatial predictor variables. Our results showed that the spatially structured environmental component was dominant through the sampling periods. Purely spatial and environmental components contributed a significant proportion of variance, but their magnitudes showed considerable temporal variation. Environmental processes were more pronounced in winter periods while purely spatial processes were augmented in the summer months. Our results suggest that species‐sorting is the primary structuring forces in waterbird communities. The presence of spatial effects, especially in summer, does however suggest that species‐sorting does not operate in isolation. Future efforts also need to address the causes and consequences of temporal variation in metacommunity processes.
Highlights
A central goal in ecology is to understand the processes that control the organization of communities through space and time
We addressed two primary questions: (1) What are the relative contributions of purely spatial, purely environmental, and spatially structured environmental fractions to the total explained variance of the beta-diversity of the waterbird community and how much variation in the waterbird communities can be attributed to stochastic variation? and (2) if purely environmental explains a significant proportion of variance in the communities, which environmental variables were most important in contributing to this explained variance? The analysis was extended to investigate the role of temporal variation in community structuring processes
Variance partitioning The total variance in the waterbird community explained by both spatial and environmental matrices ranged from 15.4 to 24.7% across different sampling periods (Table 3)
Summary
A central goal in ecology is to understand the processes that control the organization of communities through space and time. There are four perspectives (species-sorting, mass effects, patch dynamics, and the neutral model) that form the basis of metacommunity theory. The metacommunity framework can be seen as a continuum along which the species-s orting and neutral models are different endpoints of a set of processes that act on community structure. Viewing communities in this way does, pose challenges for empirical studies that seek to test the relative importance of the processes defined by the four perspectives
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
