Effects of dispersal mode on the environmental and spatial correlates of nestedness and species turnover in pond communities

Matthew J Hill,Paul J Wood,Jani Heino,David B Ryves,Ian Thornhill

doi:10.1111/oik.04266

Matthew J Hill, Paul J Wood + Show 3 more

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https://doi.org/10.1111/oik.04266

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Abstract

Advances in metacommunity theory have made a significant contribution to understanding the drivers of variation in biological communities. However, there has been limited empirical research exploring the expression of metacommunity theory for two fundamental components of beta diversity: nestedness and species turnover. In this paper, we examine the influence of local environmental and a range of spatial variables (hydrological connectivity, proximity and overall spatial structure) on total beta diversity and the nestedness and turnover components of beta diversity for the entire macroinvertebrate community and active and passively dispersing taxa within pond habitats. High beta diversity almost entirely reflects patterns of species turnover (replacement) rather than nestedness (differences in species richness) in our dataset. Local environmental variables were the main drivers of total beta diversity, nestedness and turnover when the entire community was considered and for both active and passively dispersing taxa. The influence of spatial processes on passively dispersing taxa, total beta diversity and nestedness was significantly greater than for actively dispersing taxa. Our results suggest that species sorting (local environmental variables) operating through niche processes was the primary mechanism driving total beta diversity, nestedness and turnover for the entire community and active and passively dispersing taxa. In contrast, spatial factors (hydrological connectivity, proximity and spatial eigenvectors) only exerted a secondary influence on the nestedness and turnover components of beta diversity.

Highlights

Local environmental variables alone explained more of the variance in community structure (12.5%) compared to the spatial parameters
Hydrological proximity effects and the spatial eigenvectors significantly (p 0.05) influenced species turnover for passively dispersing taxa. Both local environmental and spatial processes were important in structuring patterns of total beta diversity, nestedness and species turnover in ponds when the entire community was considered
The high beta diversity of macroinvertebrate communities among the ponds could almost entirely be attributed to species turnover, indicating that dissimilarity among ponds was largely driven by variation in community composition, rather than differences in taxonomic richness

Summary

Introduction

Ponds are ideal systems to test the relative contribution of local and spatial variables to compositional variation and the components of beta diversity (i.e. nestedness and turnover) since they are typically discrete in space, small and often demonstrate gradients across a wide range of environmental conditions (Vanschoenwinkel et al 2007, Gianuca et al 2017). Recent empirical studies examining lentic invertebrate metacommunities have concluded that local environmental variables (species sorting) are generally more important than spatial variables in driving ecological community structure (species track preferred environmental conditions; Cottenie 2005, Thornhill et al 2017), there is considerable variability amongst regions and macroinvertebrate groups (Van De Meutter et al 2007, Vanschoenwinkel et al 2007, Heino et al 2012, Tonkin et al 2016). The interaction and influence of local environmental and spatial processes on the nestedness and turnover components of beta-diversity among actively and passively dispersing taxa has received little research attention to date. High species turnover would suggest conserving a range of sites with different species composition as a priority given the high species replacement between sites

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