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Background and Aims As most plants rely on pollination for persistence in communities, pollination interactions should be important determinants of plant community assembly. Here, trait and phylogenetic null modelling approaches were combined with pollinator interaction networks to elucidate the processes structuring flower colour assembly patterns in Asteraceae communities in Namaqualand, South Africa. Methods Plant species were assigned to flower colour pattern categories (CPCs) that incorporate the complexity of the bulls-eye colour pattern, using pollinator vision models. Null models were used to assess whether daisy communities exhibit clustering (driven by filtering, facilitation or convergence) or overdispersion (driven by competitive exclusion or character displacement) of CPCs. Next, flower visitor networks were constructed for communities with non-random CPC assembly to confirm the functional role of pollinators in determining floral trait assembly. Key Results Plant species are unevenly distributed across CPCs, the majority of which are not phylogenetically conserved, suggesting that certain CPCs have a selective advantage. Clustering of CPCs in communities is more frequent than overdispersion, and this does not reflect non-random phylogenetic assembly. In most communities at least one CPC is overrepresented relative to null assemblages. Interaction networks show that each community has a single dominant pollinator that strongly interacts with the overrepresented CPC, suggesting a role for pollinator preferences in driving clustered assembly of CPCs within daisy communities. Conclusion This novel approach, which demonstrates non-random assembly of complex flower colour patterns and corroborates their functional association with particular pollinators, provides strong evidence that pollinators influence plant community assembly. Results suggest that in some community contexts the benefits of pollinator sharing outweigh the costs of heterospecific pollen transfer, generating clustered assembly. They also challenge the perception of generalized pollination in daisies, suggesting instead that complex daisy colour patterns represent a pollination syndrome trait linked to specific fly pollinators. [ABSTRACT FROM AUTHOR]

Aim Insect distribution patterns can result from historical contingency (biogeography and dispersal limitation), abiotic filtering and biotic factors (ecological interactions and evolutionary associations). Here, we analyse turnover of plant and insect herbivore community composition at multiple spatial scales to tease apart these influences. While positive associations between plant and insect turnover across broad spatial scales could arise through any of these influences, strong association at very local scales is only likely if insect distributions are determined primarily by biotic factors (i.e. host specificity). Location The Cape Floristic Region ( CFR), South Africa. Methods To characterize the relationship between spatial turnover in plant and insect composition in the CFR, communities of Restionaceae, a dominant family in the florally diverse CFR, and their associated herbivores were sampled using a spatially nested sampling design on three spatially separated mountain blocks with similar climates, thus controlling for broad abiotic influences. This allowed us to quantify insect and plant turnover, and their association, at multiple independent spatial scales. Redundancy analysis was used to determine the effects of plant on insect composition, controlling for geographical distance. Results Insect species turnover was significantly related to plant species and phylogenetic turnover at local, as well as broad, spatial scales, suggesting that insect distribution patterns are mainly structured by host specificity. Plant communities show near complete turnover at small spatial scales (i.e. communities situated 0.1-3 km apart), with insects mirroring this pattern. Further, insect turnover increased significantly with increasing geographical separation (e.g. between mountains), suggesting an additional influence of biogeographical factors on insect distributions in the CFR. Measured environmental and plant structural components had no influence on insect composition. Main conclusions High insect beta diversity positively associated with plant turnover at local scales suggests insect herbivore diversity patterns in the CFR are primarily structured by plant distribution patterns. [ABSTRACT FROM AUTHOR]