Abstract
The decomposition of beta-diversity (β-diversity) into its replacement (βrepl) and richness (βrich) components in combination with a taxonomic and functional approach, may help to identify processes driving community composition along environmental gradients. We aimed to understand which abiotic and spatial variables influence ant β-diversity and identify which processes may drive ant β-diversity patterns in Mediterranean drylands by measuring the percentage of variation in ant taxonomic and functional β-diversity explained by local environmental, regional climatic and spatial variables. We found that taxonomic and functional replacement (βrepl) primarily drove patterns in overall β-diversity (βtot). Variation partitioning analysis showed that respectively 16.8%, 12.9% and 21.6% of taxonomic βtot, βrepl and βrich variation were mainly explained by local environmental variables. Local environmental variables were also the main determinants of functional β-diversity, explaining 20.4%, 17.9% and 23.2% of βtot, βrepl and βrich variation, respectively. Findings suggest that niche-based processes drive changes in ant β-diversity, as local environmental variables may act as environmental filters on species and trait composition. While we found that local environmental variables were important predictors of ant β-diversity, further analysis should address the contribution of other mechanisms, e.g. competitive exclusion and resource partitioning, on ant β-diversity.
Highlights
The decomposition of beta-diversity (β-diversity) into its replacement and richness components in combination with a taxonomic and functional approach, may help to identify processes driving community composition along environmental gradients
We addressed the two following questions: (1) which components drive ant taxonomic and functional βtot? and (2) which abiotic factors explain variation in taxonomic and functional β-diversity and how can they help us to infer on the ecological processes driving taxonomic and functional β-diversity along climatic environmental gradients? Based on previous studies[22,25] we expected a higher contribution of the βrepl, over the βrich component, to ant βtot, and that along climatic environmental gradients, niche-based processes play the most important role in structuring ant communities
A slight negative association was found between head length (HL) and aridity, HL and mean normalized difference vegetation index (NDVI), nesting under stones and aridity, generalist diet and biomass, medium polymorphism and mean plant height, nocturnal activity and bare soil (%)
Summary
The decomposition of beta-diversity (β-diversity) into its replacement (βrepl) and richness (βrich) components in combination with a taxonomic and functional approach, may help to identify processes driving community composition along environmental gradients. Findings suggest that niche-based processes drive changes in ant β-diversity, as local environmental variables may act as environmental filters on species and trait composition. With abiotic filters, β-diversity is expected to be constant across space and increase along an environmental gradient, with communities in the same environmental conditions sharing similar traits[9,12]. High functional diversity may result either from the replacement of functionally different species, indicating abiotic filtering, or from the loss/gain of functional strategies, which may be related to a different intensity of the niche-based p rocesses[14]
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