Aim Fruit colours attract animal seed dispersers, yet the causes of fruit colour diversity remain controversial. The lack of knowledge of large‐scale spatial patterns in fruit colours has limited our ability to formulate and test alternative hypotheses to explain fruit colour, fruit size and fruit colour diversity. We describe spatial (especially latitudinal) variation in fruit colour, colour diversity and length, and test for correlations between fruit colour, length and plant habit. Location Global. Time period Present day. Major taxa studied Seed plants. Methods We assembled a database of fruit traits for 13,178 fleshy fruited plant species spanning 136 sites around the world. To assess whether fruit colour categories correspond with spectral reflectances, we tested for clustering of hue, chroma and saturation for 236 species for which we had reflectance data. We then quantified latitudinal gradients in fruit colour, fruit length and fruit colour diversity while controlling for the effects of plant habit and whether colour categories varied with respect to average fruit size. Results Colour categories corresponded well with reflectance data. The tropics show high colour diversity, while red fruits progressively constitute a higher proportion of the fleshy‐fruited plant community towards high latitudes. All mammal‐associated colours (green, orange, brown and yellow) are more common in the tropics than at high latitudes. Fruit length also increases towards the tropics. Main conclusions Tropical communities tend to have diverse fruit colours, including many mammal‐associated fruit colours, while high latitude communities contain a higher percentage of red‐fruited species. The correlation between colour and size is strong, and some latitudinal patterns may be partly driven by changes in fruit size. Differences in geography and in the history of plant lineages in the Southern versus the Northern Hemisphere may help to explain some biogeographic patterns, but alternative hypotheses related to fruit defence, development and metabolic costs are plausible.

Premise: A key question in plant dispersal via animal vectors is where and why fruit colors vary between species and how color relates to other fruit traits. To better understand the factors shaping the evolution of fruit color diversity, we tested for the existence of syndromes of traits (color, morphology, and nutrition) in the fruits of Viburnum. We placed these results in a larger phylogenetic context and reconstructed ancestral states to assess how Viburnum fruit traits have evolved across the clade. Results: We find that blue Viburnum fruits are not very juicy, and have high lipid content and large, round endocarps surrounded by a small quantity of pulp. Red fruits display the opposite suite of traits: they are very juicy with low lipid content and smaller, flatter endocarps. The ancestral Viburnum fruit may have gone through a sequence of color changes before maturation (green to yellow to red to black), though our reconstructions are equivocal. In one major clade of Viburnum (Nectarotinus), fruits mature synchronously with reduced intermediate color stages. Most transitions between fruit colors occurred in this synchronously fruiting clade. Conclusions: It is widely accepted that fruit trait diversity has primarily been driven by the differing perceptual abilities of bird versus mammal frugivores. Yet within a clade of largely bird-dispersed fruits, we find clear correlations between color, morphology, and nutrition. These correlations are likely driven by a shift from sequential to synchronous development, followed by diversification in color, nutrition, and morphology. A deeper understanding of fruit evolution within clades will elucidate the degree to which such syndromes structure extant fruit diversity.

Viburnum tinus is an evergreen shrub that is native to the Mediterranean region but cultivated widely in Europe and around the world. It produces ripe metallic blue fruits throughout winter [1]. Despite its limited fleshy pulp,[2] its high lipid content[3] makes it a valuable resource to the small birds[4] that act as its seed-dispersers [5]. Here, we find that the metallic blue appearance of the fruits is produced by globular lipid inclusions arranged in a disordered multilayer structure. This structure is embedded in the cell walls of the epicarp and underlaid with a dark layer of anthocyanin pigments. The presence of such large, organised lipid aggregates in plant cell walls represents a new mechanism for structural colouration and may serve as an honest signal of nutritional content. 639088 (S.V., Y.O., G.J.), a microMORPH Cross-Training Grant (M.S.A.), a Yale Institute for Biospheric Studies grant (M.S.A.), National Science Foundation (NSF)SF GRFP DGE-1122492 (M.S.A.), and NSF DBI 1907293 (M.S.A.). We would like to acknowledge the assistance of the Boulder Electron Microscopy Service in preparation and imaging the serial block-face, and the support of the Cambridge Advanced Imaging Centre and the NanoBio-ICMG platform (FR 2607) electron microscopy facility. We are grateful to Heather Whitney and Innes Cuthill for loan of equipment and to two anonymous referees for advice and comments which improved the manuscript.

The colours of fleshy fruits play a critical role in plant dispersal by advertising ripe fruits to consumers. Fruit colours have long been classified into syndromes attributed to selection by animal dispersers, despite weak evidence for this hypothesis. Here, we test the relative importance of biotic (bird and mammal frugivory) and abiotic (wet season temperatures, growing season length and UV‐B radiation) factors in determining fruit colour syndrome in 3163 species of fleshy‐fruited plants. We find that both dispersers and environment are important, and they interact. In warm areas, contrastive, bird‐associated fruit colours increase with relative bird frugivore prevalence, whereas in cold places these colours dominate even where mammalian dispersers are prevalent. We present near‐global maps of predicted fruit colour syndrome based on our species‐level model and our newly developed characterisations of relative importance of bird and mammal frugivores.

The evolution of ecological idiosyncrasies in Madagascar has often been attributed to selective pressures stemming from extreme unpredictability in climate and resource availability compared to other tropical areas. With the exception of rainfall, few studies have investigated these assumptions. To assess the hypothesis that Madagascar’s paucity of frugivores is due to unreliability in fruiting resources, we use statistical modeling to analyze phenology datasets and their environmental correlates from two tropical wet forests, the Réserve Naturelle Intégrale Betampona in Madagascar, and Kibale National Park in Uganda. At each site we found that temperature is a good environmental predictor of fruit availability. We found no evidence of a significant difference in the predictability of fruit availability between the two sites, although the shorter duration of phenological monitoring at Betampona (two years, versus 15 years at Kibale) limits our ability to infer long-term patterns. Comparisons of long-term temperature data from each site (15 years from Kibale and 14 from Betampona) indicate that temperature is more predictable at Betampona than at Kibale. However, there does appear to be a difference between the two sites in the total fruit availability at any given time, with fruit being generally less abundant at Betampona. Our results appear contrary to the prevailing hypothesis of a selective force imposed by unpredictable resource availability or temperature, and we suggest other possible explanations for Madagascar’s unique biota.

The presence of SMFs significantly increased pollinator attraction and female reproductive success both in contemporary and simulated ancestral contexts, indicating that stabilizing selection is responsible for their maintenance, and directional selection likely drove their evolution when they first appeared. This study demonstrates a novel approach to incorporating historically relevant scenarios into experimental studies of floral evolution.

The majority of plant colours are produced by anthocyanin and carotenoid pigments, but colouration obtained by nanostructured materials (i.e. structural colours) is increasingly reported in plants. Here, we identify a multilayer photonic structure in the fruits of Lantana strigocamara and compare it with a similar structure in Viburnum tinus fruits.We used a combination of transmission electron microscopy (EM), serial EM tomography, scanning force microscopy and optical simulations to characterise the photonic structure in L. strigocamara. We also examine the development of the structure during maturation.We found that the structural colour derives from a disordered, multilayered reflector consisting of lipid droplets of c.105 nm that form a plate-like structure in 3D. This structure begins to form early in development and reflects blue wavelengths of light with increasing intensity over time as the structure develops. The materials used are likely to be lipid polymers.Lantana strigocamara is the second origin of a lipid-based photonic structure, convergently evolved with the structure in Viburnum tinus. Chemical differences between the lipids in L. strigocamara and those of V. tinus suggest a distinct evolutionary trajectory with implications for the signalling function of structural colours in fruits.

Syndromes, wherein multiple traits evolve convergently in response to a shared selective driver, form a central concept in ecology and evolution. Recent work has questioned the utility and indeed the existence of some of the classic syndromes, such as pollination and seed dispersal syndromes. Here, we discuss some of the major issues that have plagued research into syndromes in macroevolution. First, observation of co-evolving traits (sometimes called "trait syndromes'') is often used as evidence of adaptation to a particular driver, even when the link between traits and adaptation is not well-tested. Second, the study of syndromes often uses a biased sampling approach, focusing on the most extreme examples, which may obscure significant continuous variation between traits. Finally, researchers often focus on the traits that are easiest to measure even though these may not be the most directly relevant to adaptive hypotheses. We argue that these issues can be avoided by combining macroevolutionary studies of trait variation across entire clades with explicit tests of adaptive hypotheses, and that taking this approach will lead to a better understanding of syndrome-like evolution and its drivers.