Many recent studies have suggested that the majority of animal-pollinated plants have a higher diversity of pollinators than that expected according to their pollination syndrome. This broad generalization, often based on pollination web data, has been challenged by the fact that some floral visitors recorded in pollination webs are ineffective pollinators. To contribute to this debate, and to obtain a contrast between visitors and pollinators, we studied insect and bird visitors to virgin flowers of Hypoestes aristata in the Bamenda Highlands, Cameroon. We observed the flowers and their visitors for 2-h periods and measured the seed production as a metric of reproductive success. We determined the effects of individual visitors using 2 statistical models, single-visit data that were gathered for more frequent visitor species, and frequency data. This approach enabled us to determine the positive as well as neutral or negative impact of visitors on H. aristata's reproductive success. We found that (i) this plant is not generalized but rather specialized; although we recorded 15 morphotaxa of visitors, only 3 large bee species seemed to be important pollinators; (ii) the carpenter bee Xylocopa cf. inconstans was both the most frequent and the most effective pollinator; (iii) the honey bee Apis mellifera acted as a nectar thief with apparent negative effects on the plant reproduction; and (iv) the close relationship between H. aristata and carpenter bees was in agreement with the large-bee pollination syndrome of this plant. Our results highlight the need for studies detecting the roles of individual visitors. We showed that such an approach is necessary to evaluate the pollination syndrome hypothesis and create relevant evolutionary and ecological hypotheses.

• MeSH
• Acanthaceae fyziologie   MeSH
• hmyz fyziologie   MeSH
• květy MeSH
• opylení * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Kamerun MeSH

Since the time of Darwin, biologists have considered the floral nectar spur to be an adaptation representing a high degree of plant specialization. Nevertheless, some researchers suggest that nature is more complex and that even morphologically specialized plants attract a wide spectrum of visitors. We observed visitors on Impatiens burtonii (Balsaminaceae) and measured the depth of the proboscis insertion into the spur, the distance of the nectar surface from the spur entrance and the visitor's effectiveness. The hoverfly Melanostoma sp., with the shortest proboscis, was most active early in the morning and fed on pollen and nectar near the spur entrance. The honeybee Apis mellifera and the hoverfly Rhingia mecyana were the most frequent visitors before and after noon, respectively. Although R. mecyana, the only visitor able to reach the end of the spur, was the most frequent, it did not deposit the largest number of pollen grains per visit. Nectar spurs may function as complex structures allowing pollination by both short- and long-proboscid visitors and separating their spatial and temporal niches. Spurred plants should be considered as more generalized and exposed to more diverse selection pressures than previously believed.

• MeSH
• chování zvířat fyziologie   MeSH
• cirkadiánní rytmus fyziologie   MeSH
• hmyz fyziologie   MeSH
• Impatiens fyziologie   MeSH
• opylení fyziologie   MeSH
• rostlinný nektar metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

We use the optimal foraging theory to study coexistence between two plant species and a generalist pollinator. We compare conditions for plant coexistence for non-adaptive vs. adaptive pollinators that adjust their foraging strategy to maximize fitness. When pollinators have fixed preferences, we show that plant coexistence typically requires both weak competition between plants for resources (e.g., space or nutrients) and pollinator preferences that are not too biased in favour of either plant. We also show how plant coexistence is promoted by indirect facilitation via the pollinator. When pollinators are adaptive foragers, pollinator's diet maximizes pollinator's fitness measured as the per capita population growth rate. Simulations show that this has two conflicting consequences for plant coexistence. On the one hand, when competition between pollinators is weak, adaptation favours pollinator specialization on the more profitable plant which increases asymmetries in plant competition and makes their coexistence less likely. On the other hand, when competition between pollinators is strong, adaptation promotes generalism, which facilitates plant coexistence. In addition, adaptive foraging allows pollinators to survive sudden loss of the preferred plant host, thus preventing further collapse of the entire community.

• MeSH
• biologické modely MeSH
• fyziologická adaptace * MeSH
• molekulární evoluce MeSH
• opylení * MeSH
• rostliny * MeSH
• symbióza * MeSH
• Publikační typ
• časopisecké články MeSH

The plant life cycle is often affected by animal-plant interactions. In insect-pollinated plants, interaction with pollinators is very important. When pollen transfer due to a lower abundance of pollinators limits seed production, selection pressures on plant traits related to plant attraction to pollinators might occur, e.g. on flowering phenology, height or number of flowerheads. Landscape changes (e.g. habitat fragmentation or changed habitat conditions) may cause plant-pollinator systems to lose balance and consequently affect population dynamics of many plant species. We studied the relationship between measured plant traits, environmental variables and pollinator preferences in Scorzonera hispanica (Asteraceae), a rare perennial, allogamous herb of open grasslands. We estimated the pollen limitation by comparing seed set of supplemental-pollinated plants with that of open-pollinated ones. Pollinators selected plants based on position within the locality (isolated plants close to trees) rather than on their traits. In spite of a high proportion of undeveloped seeds on the plants, we demonstrated that they are not pollen limited. Instead, seed set and weight of seeds was correlated with plant size traits (height and flowerhead number), with larger plants producing more and larger seeds. This suggests that the studied plants are likely resource limited. Overall, the results suggest that pollinators are not a selection factor in this system, in contrast to studies on various plant species, including self-compatible species of the Asteraceae. The lack of any effect of pollinators in the system may be caused by a strong negative effect of ungulate herbivores, which could play a decisive role in functioning of the system.

• MeSH
• chování zvířat MeSH
• ekosystém MeSH
• hmyz fyziologie   MeSH
• květy anatomie a histologie   růst a vývoj   fyziologie   MeSH
• opylení * MeSH
• populační dynamika MeSH
• rozmnožování MeSH
• Scorzonera anatomie a histologie   růst a vývoj   fyziologie   MeSH
• selekce (genetika) MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Specific pollen placement by zygomorphic flowers on pollinators is one of the key innovations of angiosperm evolution [1]. In most phylogenetic lineages that have evolved zygomorphic flowers, reproductive organs are positioned either in the lower or upper part of the flower. Although these specific positions largely enhance pollen economy, they also represent architectural constraints such that flowers are able to place pollen only on the dorsal or ventral part of pollinators' bodies [2]. Such constraints can lead to interspecific pollen placement in situations where phylogenetically related species with the same floral architecture share pollinators [3].

• MeSH
• biologická evoluce MeSH
• Impatiens fyziologie   MeSH
• opylení * MeSH
• stravovací zvyklosti * MeSH
• zpěvní ptáci fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• dopisy MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Kamerun MeSH

Cockroaches have rarely been documented as pollinators. In this paper we examine whether this is because they might be inefficient at pollination compared to other pollinators. Clusia blattophila, a dioecious shrub growing on isolated rocky outcrops in French Guiana, is pollinated by Amazonina platystylata cockroaches and provides a valuable system for the study of cockroach pollination efficiency. We examined the species composition of the visitor guild and visitation rates by means of camcorder recordings and visitor sampling. Then, we investigated the capacity for pollen transfer of principal visitors and found correlations between visitation rates and pollen loads on stigmas. In an exclusion experiment we determined the contributions of individual species to pollination success. Amazonina platystylata, crickets and two species of Diptera transferred pollen, but the number of transferred pollen grains was only related to visitation rates in the case of cockroaches. Crickets visited and rarely carried pollen. Dipterans were as frequent as cockroaches, carried similar pollen loads, but transferred much less pollen. An estimated 41% and 17% of ovules were pollinated by cockroaches and dipterans, respectively. The remaining ovules were not pollinated. There was no spatial variation in pollinator guild composition, but cockroaches visited flowers less frequently at the smaller study site. We demonstrate that cockroaches pollinate a large proportion of ovules. Their pollination service is not confined to one study site and, unlike that provided by dipterans, is not limited to certain years. We suggest that cockroach pollination has been overlooked and that cockroach-pollinated plants, which share certain floral features, possess adaptations to pollination by cockroaches.

• MeSH
• Clusia anatomie a histologie   fyziologie   MeSH
• Diptera fyziologie   MeSH
• Gryllidae fyziologie   MeSH
• květy anatomie a histologie   fyziologie   MeSH
• opylení * fyziologie   MeSH
• švábi * fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Francouzská Guyana MeSH

In plant-pollinator communities many pollinators are potential generalists and their preferences for certain plants can change quickly in response to changes in plant and pollinator densities. These changes in preferences affect coexistence within pollinator guilds as well as within plant guilds. Using a mathematical model, we study how adaptations of pollinator preferences influence population dynamics of a two-plant-two-pollinator community interaction module. Adaptation leads to coexistence between generalist and specialist pollinators, and produces complex plant population dynamics, involving alternative stable states and discrete transitions in the plant community. Pollinator adaptation also leads to plant-plant apparent facilitation that is mediated by changes in pollinator preferences. We show that adaptive pollinator behavior reduces niche overlap and leads to coexistence by specialization on different plants. Thus, this article documents how adaptive pollinator preferences for plants change the structure and coexistence of plant-pollinator communities.

• MeSH
• biologické modely * MeSH
• fertilita MeSH
• fyziologická adaptace MeSH
• fyziologie rostlin MeSH
• opylení * MeSH
• populační dynamika MeSH
• teoretické modely * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Cascading or reciprocal genetic diversification of herbivores, parasitoids, and pollinators can track chemotypic variation in host resources, and can lead to non-overlapping communities. Because plants simultaneously interact with both pollinators and herbivores, models investigating the genetic divergence of antagonistic herbivores and mutualistic pollinators should be merged in order to study how both processes interact using a common conceptual and methodological approach. We expect insects to mediate divergence in many systems, with outcomes depending on the level of pollinator or herbivore specialisation, and the relative selective pressures they impose. Applying approaches widely used to study insect pollinators, for example genomic tools and integration of behavioural, genetic and chemical data, to both pollinators and herbivores in the same system will facilitate our understanding of patterns of genetic divergence across multiple interacting species.

• MeSH
• biologická evoluce MeSH
• býložravci MeSH
• fyziologie rostlin MeSH
• hmyz genetika   fyziologie   MeSH
• opylení MeSH
• rostliny chemie   genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Generalist pollinators are important in many habitats, but little research has been done on small-scale spatial variation in interactions between them and the plants that they visit. Here, using a spatially explicit approach, we examined whether multiple species of flowering plants occurring within a single meadow showed spatial structure in their generalist pollinator assemblages. We report the results for eight plant species for which at least 200 individual visits were recorded. We found that for all of these species, the proportions of their general pollinator assemblages accounted for by particular functional groups showed spatial heterogeneity at the scale of tens of metres. This heterogeneity was connected either with no or only subtle changes of vegetation and flowering species composition. In five of these species, differences in conspecific plant density influenced the pollinator communities (with greater dominance of main pollinators at low-conspecific plant densities). The density of heterospecific plant individuals influenced the pollinator spectrum in one case. Our results indicate that the picture of plant-pollinator interactions provided by averaging data within large plots may be misleading and that within-site spatial heterogeneity should be accounted for in terms of sampling effort allocation and analysis. Moreover, spatially structured plant-pollinator interactions may have important ecological and evolutionary consequences, especially for plant population biology.

• MeSH
• biologická evoluce MeSH
• brouci fyziologie   MeSH
• Diptera klasifikace   fyziologie   MeSH
• distribuce rostlin MeSH
• ekosystém MeSH
• hustota populace MeSH
• květy fyziologie   MeSH
• Magnoliopsida fyziologie   MeSH
• motýli fyziologie   MeSH
• opylení fyziologie   MeSH
• pyl MeSH
• symbióza MeSH
• včely fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Biotic interactions play an important role in species distribution models, whose ignorance may cause an overestimation of species' potential distributions. Species of the family Orchidaceae are almost totally dependent on mycorrhizal symbionts and pollinators, with sexually deceptive orchids being often highly specialized, and thus the interactions with their pollinators are expected to strongly affect distribution predictions. We used Maxent algorithm to explore the extent of current and future habitat suitability for two Greek endemic sexually deceptive orchids (Ophrys argolica and Ophrys delphinensis) in relation to the potential distribution of their unique pollinator (Anthophora plagiata). Twelve climate change scenarios were used to predict future distributions. Results indicated that the most important factors determining potential distribution were precipitation seasonality for O. argolica and geological substrate for O. delphinensis. The current potential distribution of the two orchids was almost of the same extent but spatially different, without accounting for their interaction with A. plagiata. When the interaction was included in the models, their potentially suitable area decreased for both species. Under future climatic conditions, the effects of the orchid-pollinator interaction were more intense. Specifically, O. argolica was restricted in specific areas of southern Greece, whereas O. delphinensis was expected to become extinct. Our findings highlighted the significant role of plant-pollinator interactions in species distribution models. Failing to study such interactions might expose plant species to serious conservation issues.

• MeSH
• biologická evoluce * MeSH
• klimatické změny * MeSH
• květy fyziologie   MeSH
• opylení fyziologie   MeSH
• Orchidaceae fyziologie   MeSH
• teoretické modely * MeSH
• včely MeSH
• zachování přírodních zdrojů * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH