The relative importance of color signaling for plant generalization in pollination networks (original) (raw)
Related papers
Characterizing ecological generalization in plant-pollination systems
Oecologia, 2006
Despite the development of diversity indices in community ecology that incorporate both richness and evenness, pollination biologists commonly use only pollinator richness to estimate generalization. Similarly, while pollination biologists have stressed the utility of pollinator importance, incorporating both pollinator abundance and effectiveness, importance values have not been included in estimates of generalization in pollination systems. In this study, we estimated pollinator generalization for 17 plant species using Simpson's diversity index, which includes richness and evenness. We compared these estimates with estimates based on only pollinator richness, and compared diversity estimates calculated using importance data with those using only visitation data. We found that pollinator richness explains only 57-65% of the variation in diversity, and that, for most plant species, pollinator importance was determined primarily by differences in visitation rather than by differences in effectiveness. While simple richness may suffice for broad comparisons of pollinator generalization, measures that incorporate evenness will provide a much more accurate understanding of generalization. Although incorporating labor-intensive measurements of pollinator effectiveness are less necessary for broad surveys, effectiveness estimates will be important for detailed studies of some plant species. Unfortunately, at this point it is impossible to predict a priori which species these are.
Disentangling the path of pollinator attraction in temporarily colored flowers
International Journal of Tropical Insect Science
Plants may use different strategies to attract pollinators in long distance (e.g. floral display) and in short distance (e.g. ratio between differentially colored flowers) scales. The Verbenaceae Lantana canescens Kunth is a wide spread species in open sites of the Brazilian Pantanal wetland. Individuals of this generalist species can produce a variable number of open inflorescences with yellow and white flowers that are organized in whorls. In this study we tested the hypothesis that increased floral display (long distance attraction) and the ratio between yellow and white flowers (short distance attraction) enhances the number of pollinator species and individuals. We observed flower visitors and calculated floral parameters in 38 plots of 1 m2 each, that contained a varying number of flowering L. canescens individuals. Non-metric multidimensional scaling and Bray-Curtis distances were used to account for flower visitor composition and the relative visitation rate, respectively. W...
Do pollinators influence the assembly of flower colours within plant communities?
Oecologia, 2011
The co-occurrence of plant species within a community is influenced by local deterministic or neutral processes as well as historical regional processes. Floral trait distributions of co-flowering species that share pollinators may reflect the impact of pollinator preference and constancy on their assembly within local communities. While pollinator sharing may lead to increased visitation rates for species with similar flowers, the receipt of foreign pollen via interspecific pollinator movements can decrease seed set. We investigated the pattern of community flower colour assembly as perceived by native honeybee pollinators within 24 local assemblages of co-flowering Oxalis species within the Greater Cape Floristic Region, South Africa. To explore the influence of pollinators on trait assembly, we assessed the impact of colour similarity on pollinator choices and the cost of heterospecific pollen receipt. We show that flower colour is significantly clustered within Oxalis communities and that this is not due to historical constraint, as flower colour is evolutionarily labile within Oxalis and communities are randomly structured with respect to phylogeny. Pollinator observations reveal that the likelihood of pollinators switching between co-flowering species is low and increases with flower colour similarity. Interspecific hand pollination significantly reduced seed set in the four Oxalis species we investigated, and all were dependant on pollinators for reproduction. Together these results imply that flower colour similarity carries a potential fitness cost. However, pollinators were highly flower constant, and remained so despite the extreme similarity of flower colour as perceived by honeybees. This suggests that other floral traits facilitate discrimination between similarly coloured species, thereby likely resulting in a low incidence of interspecific pollen transfer (IPT). If colour similarity promotes pollinator attraction at the community level, the observed clustering of flower colour within communities might result from indirect facilitative interactions.
POLLINATION NETWORKS : GEOGRAPHIC PATTERNS conceptualization is in its very first phase (
Recent reviews of plant–pollinator mutualistic networks showed that generalization is a common pattern in this type of interaction. Here we examine the ecological correlates of generalization patterns in plant–pollinator networks, especially how interaction patterns covary with latitude, elevation, and insularity. We review the few published analyses of whole networks and include unpublished material, analyzing 29 complete plant– pollinator networks that encompass arctic, alpine, temperate, Mediterranean, and subtropical–tropical areas. The number of interactions observed (I) was a linear function of network size (M ) the maximum number of interactions: ln I 5 0.575 1 0.61 ln M; R2 5 0.946. The connectance (C), the fraction of observed interactions relative to the total possible, decreased exponentially with species richness, the sum of animal and plant species in each community (A 1 P): C 5 13.83 exp[20.003(A 1 P)]. After controlling for species richness, the residual connectance w...
Floral colour diversity in plant communities, bee colour space and a null model
Proceedings of the Royal Society B: Biological Sciences, 1999
Evolutionary biologists have long hypothesized that the diversity of £ower colours we see is in part a strategy to promote memorization by pollinators, pollinator constancy, and therefore, a directed and e¤cient pollen transfer between plants. However, this hypothesis has never been tested against a biologically realistic null model, nor were colours assessed in the way pollinators see them. Our intent here is to ¢ll these gaps. Throughout one year, we sampled £oral species compositions at ¢ve ecologically distinct sites near Berlin, Germany. Bee-subjective colours were quanti¢ed for all 168 species. A model of colour vision was used to predict how similar the colours of sympatric and simultaneously blooming £owers were for bees. We then compared £ower colour di¡erences in the real habitats with those of random plant communities. We did not ¢nd pronounced deviations from chance when we considered common plants. When we examined rare plants, however, we found signi¢cant divergence in two of the ¢ve plant communities. At one site, similarly coloured species were found to be more frequent than expected, and at the other two locations, £ower colours were indistinguishable from a random distribution. These results ¢t theoretical considerations that rare plants are under stronger selective pressure to secure pollination than common plants. Our study illustrates the power of linking such distinct biological traditions as community ecology and the neuroethology of bee vision.
Functional Ecology, 2007
1. While many plant species offer rewards (e.g. nectar) to pollinators, some species, particularly in orchids, do not provide rewards. Ecological factors, such as interactions with rewarding co-flowering species may affect pollinator visitation rates to such deceptive species by influencing pollinator ability to learn to avoid deceptive plants (avoidance learning). 2. We tested the effect of flower colour similarity (similar vs dissimilar) and fine-scale spatial mingling (monospecific vs heterospecific patches) of rewarding and deceptive artificial plants on pollinator visitation in a fully crossed design. We also examined the effect of these factors on learning of initially naïve bumblebees. 3. Over time, bumblebees increasingly avoided the deceptive plants, but at a significantly faster rate when deceptive and rewarding plants had dissimilar flower colours than when they were similar. 4. Deceptive plants received more visits when mingled in heterospecific patches with rewarding plants of similar flower colour than when mingled with dissimilar ones. This difference was not significant when rewarding and deceptive plants were spatially separated in monospecific patches. 5. In conclusion, both spatial mingling and flower colour similarity affected pollinator visitation to and avoidance learning of deceptive plants. This proves the validity of artificial experimental systems to study the isolated and joint effect of plant traits, and ecological factors that are crucial for the maintenance of deceptive species in natural populations.
Pollinator diversity affects plant reproduction and recruitment: the tradeoffs of generalization
Oecologia, 2007
One outstanding and unsolved challenge in ecology and conservation biology is to understand how pollinator diversity affects plant performance. Here, we provide evidence of the functional role of pollination diversity in a plant species, Erysimum mediohispanicum (Brassicaceae). Pollinator abundance, richness and diversity as well as plant reproduction and recruitment were determined in eight plant populations. We found that E. mediohispanicum was generalized both at the regional and local (population) scale, since its flowers were visited by more than 100 species of insects with very different morphology, size and behaviour. However, populations differed in the degree of generalization. Generalization correlated with pollinator abundance and plant population size, but not with habitat, ungulate damage intensity, alti-tude or spatial location. More importantly, the degree of generalization had significant consequences for plant reproduction and recruitment. Plants from populations with intermediate generalization produced more seeds than plants from populations with low or high degrees of generalization. These differences were not the result of differences in number of flowers produced per plant. In addition, seedling emergence in a common garden was highest in plants from populations with intermediate degree of generalization. This outcome suggests the existence of an optimal level of generalizations even for generalized plant species.
PloS one, 2015
When pollinators use flower color to locate food sources, a distinct color can serve as a reproductive barrier against co-flowering species. This anti-interference function of flower color may result in a community assembly of plant species displaying mutually different flower colors. However, such color dispersion is not ubiquitous, suggesting a variable selection across communities and existence of some opposing factors. We conducted a 30-week study in a plant community and measured the floral reflectances of 244 species. The reflectances were evaluated in insect color spaces (bees, swallowtails, and flies), and the dispersion was compared with random expectations. We found that co-existing colors were overdispersed for each analyzed pollinator type, and this overdispersion was statistically significant for bees. Furthermore, we showed that exclusion of 32 aliens from the analysis significantly increased the color dispersion of native flowers in every color space. This result indi...
Biological Journal of the Linnean Society, 2020
Learning plays an important role in the location and utilization of nectar sources for pollinators. In this work we focus on the plant-pollinator interaction between the butterfly Agraulis vanillae (Nymphalidae) and two Glandularia plant species (Verbenaceae) that grow in sympatry. Bioassays using arrays of artificial flowers (red vs. lilac-purple) showed that naïve A. vanillae butterflies do not have innate colour preferences for any of the tested colours. Trained butterflies were able to learn to associate both floral colours with the presence of nectar rewards. Wild A. vanillae butterflies visited the red flowers of Glandularia peruviana much more frequently than the lilac-purple flowers of Glandularia venturii. Standing nectar crop measurements showed that G. peruviana flowers offered three times more sucrose than the flowers of G. venturii. Analyses confirmed that corolla colour of G. peruviana (red flowers) and G. venturii (lilac-purple flowers) were discriminable in the butte...