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Floral apparency is shaped by both mutualistic and antagonistic interactions that can act in opposing ways. Pollinators are expected to select for more visually apparent flowers, but this likely trades off against the potentially severe fitness costs of damage to apparent flowers by floral herbivores. One way in which flowers that close during parts of the day might circumvent this trade‐off is by evolving less visible lower petal surfaces that are inconspicuous to herbivores when flowers are closed.Here, we used visual system modelling and herbivory experiments to test whether petal surfaces that are exposed when flowers are closed are cryptically coloured. We collected lower and upper petal surface spectra for 77 Asteraceae species from Namaqualand, South Africa. This included closing species that expose their lower petal surfaces for 5–6 daylight hours and non‐closing species that do not expose their lower surfaces. We used these contrasting groups to test the expectation of reduced conspicuousness of lower petal surfaces in closing, but not non‐closing species.By modelling reflectance spectra of petal surfaces against a green leaf background in various visual systems, we showed (a) that conspicuousness of upper petal surfaces to pollinators and various herbivores was strongly correlated, suggesting the potential for fitness trade‐offs between attracting mutualists and antagonists to open flowers, (b) that closing species' lower petal surfaces were less visible to herbivores against a leaf background than those of non‐closing species and (c) that closing species had larger differences between upper and lower petal surface coloration than non‐closing species. Behavioural experiments with tortoise herbivores demonstrated that flowers are easily detected when upper surfaces are exposed, but that tortoises were unable to distinguish lower petal surfaces against a leaf background, resulting in reduced flower herbivory.These results are consistent with selection by herbivores for cryptic coloration of lower petal surfaces, and divergence of coloration between lower and upper petal surfaces in species with closing flowers. Visual crypsis of flowers may be an effective anti‐herbivory strategy during times when pollinators are inactive, and provides an alternative to chemical defence, which often involves costs to pollination. A free Plain Language Summary can be found within the Supporting Information of this article. [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]

Globally plant species richness is a significant predictor of insect richness. Whether this is the result of insect diversity responding directly to plant diversity, or both groups responding in similar ways to extrinsic factors, has been much debated. Here we assess this relationship in the Cape Floristic Region (CFR), a biodiversity hotspot. The CFR has higher plant diversity than expected from latitude (i.e., abiotic conditions), but very little is known about the diversity of insects residing in this region. We first quantify diversity relationships at multiple spatial scales for one of the dominant plant families in the CFR, the Restionaceae, and its associated insect herbivore community. Plant and insect diversity are significantly positively correlated at the local scales (10–50 m; 0.1–3 km), but not at the regional scales (15–20 km; 50–70 km). The local scale relationship remains significantly positively correlated even when accounting for the influence of extrinsic variables and other vegetation attributes. This suggests that the diversity of local insect assemblages may be more strongly influenced by plant species richness than by abiotic variables. Further, vegetation age and plant structural complexity also influenced insect richness. The ratio of insect species per plant species in the CFR is comparable to other temperate regions around the world, suggesting that the insect diversity of the CFR is high relative to other areas of the globe with similar abiotic conditions, primarily as a result of the unusually high plant diversity in the region. [ABSTRACT FROM AUTHOR]