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Partitioning the impact of environment and spatial structure on alpha and beta components of taxonomic, functional, and phylogenetic diversity in European ants
We analyze the relative contribution of environmental and spatial variables to the
alpha and beta components of taxonomic (TD), phylogenetic (PD), and functional
(FD) diversity in ant communities found along different climate and anthropogenic
disturbance gradients across western and central Europe, in order to assess the
mechanisms structuring ant biodiversity. To this aim we calculated alpha and beta
TD, PD, and FD for 349 ant communities, which included a total of 155 ant species;
we examined 10 functional traits and phylogenetic relatedness. Variation partitioning
was used to examine how much variation in ant diversity was explained by environmental
and spatial variables. Autocorrelation in diversity measures and each trait’s
phylogenetic signal were also analyzed.We found strong autocorrelation in diversity
measures. Both environmental and spatial variables significantly contributed to
variation in TD, PD, and FD at both alpha and beta scales; spatial structure had
the larger influence. The different facets of diversity showed similar patterns along
environmental gradients. Environment explained a much larger percentage of
variation in FD than in TD or PD. All traits demonstrated strong phylogenetic
signals. Our results indicate that environmental filtering and dispersal limitations
structure all types of diversity in ant communities. Strong dispersal limitations
appear to have led to clustering of TD, PD, and FD in western and central Europe,
probably because different historical and evolutionary processes generated different
pools of species. Remarkably, these three facets of diversity showed parallel
patterns along environmental gradients. Trait-mediated species sorting and niche
conservatism appear to structure ant diversity, as evidenced by the fact that more
variation was explained for FD and that all traits had strong phylogenetic signals.
Since environmental variables explained much more variation in FD than in PD,
functional diversity should be a better indicator of community assembly processes
than phylogenetic diversityPeer reviewe