Higher pollinator effectiveness by specialist than generalist flower-visitors of unspecialized Knautia arvensis (Dipsacaceae)

AbstractAccurate predictions of pollination service delivery require a comprehensive understanding of the interactions between plants and flower visitors. To improve measurements of pollinator performance underlying such predictions, we surveyed visitation frequency, pollinator effectiveness (pollen deposition ability) and pollinator importance (the product of visitation frequency and effectiveness) of flower visitors in a diverse Mediterranean flower meadow. With these data we constructed the largest pollinator importance network to date and compared it with the corresponding visitation network to estimate the specialisation of the community with greater precision. Visitation frequencies at the community level were positively correlated with the amount of pollen deposited during individual visits, though rarely correlated at lower taxonomic resolution. Bees had the highest levels of pollinator effectiveness, with Apis, Andrena, Lasioglossum and Osmiini bees being the most effective visitors to a number of plant species. Bomblyiid flies were the most effective non-bee flower visitors. Predictions of community specialisation (H2′) were higher in the pollinator importance network than the visitation network, mirroring previous studies. Our results increase confidence in existing measures of pollinator redundancy at the community level using visitation data, while also providing detailed information on interaction quality at the plant species level.

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Types of Flower Visitors: Syndromes, Constancy, and Effectiveness

Pollination and Floral Ecology ◽

10.23943/princeton/9780691128610.003.0011 ◽

2011 ◽

Author(s):

Pat Willmer

Keyword(s):

Adaptive Radiation ◽

Convergent Evolution ◽

Pollination Syndromes ◽

Pollinator Effectiveness ◽

Flower Constancy ◽

Flower Visitors ◽

Floral Constancy ◽

Effective Pollinators

This chapter examines pollination syndromes, floral constancy, and pollinator effectiveness. Flowers show enormous adaptive radiation, but the same kind of flower reappears by convergent evolution in many different families. Thus many families produce rather similar, simple bowl-shaped flowers like buttercups; many produce similar zygomorphic tubular lipped flowers; and many produce fluffy flower heads of massed (often white) florets. These broad flower types are the basis of the idea of pollination syndromes—the flowers have converged on certain morphologies and reward patterns because they are exploiting the abilities and preferences of particular kinds of visitor. After providing an overview of pollination syndromes, the chapter explains why pollination syndromes can be defended. It then considers flower constancy, along with the distinction between flower visitors and effective pollinators. It concludes with some observations on how flower visitors can contribute to speciation of plants through specialization and through their constancy.

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Floral biology and a pollinator effectiveness test of the diurnal floral visitors of Tabernaemontana undulata Vahl. (Apocynaceae) in the understory of Amazon Rainforest, Brazil

Acta Botanica Brasilica ◽

10.1590/s0102-33062011000200014 ◽

2011 ◽

Vol 25 (2) ◽

pp. 380-386 ◽

Cited By ~ 4

Author(s):

Thaysa Nogueira de Moura ◽

Antonio Carlos Webber ◽

Liliane Noemia Melo Torres

Keyword(s):

Relative Abundance ◽

Floral Biology ◽

Fruit Production ◽

Primary Forest ◽

Pollinator Effectiveness ◽

Indirect Measure ◽

Flower Visitors ◽

Functional Regions ◽

Disturbed Area ◽

Floral Visitor

In this paper we examined the floral biology, per-visit effectiveness, frequency of visits and relative abundance of the diurnal floral visitor taxa of T. undulata (Apocynaceae) at two populations located in the primary forest and in a disturbed area connected to the continuous forest. Its hermaphrodite flowers show a long and narrow floral tube and introrse anthers form a cone around the apex of the style head where the pollen is deposited. The stigmatic head has three functional regions, in a complex pollination mechanism favoring cross-pollination. In the pollinator censuses conducted in the primary forest population we registered Eulaema bombiformis. In the disturbed area Euglossa sp. was responsible for visits on T. undulata fl owers. Eulaema bombiformis was not absent in the disturbed area, but preferred to forage on pollen and nectar-rich flowers of two neighboring flowering species. In the primary forest, T. undulata was the only fl owering treelet at the end of the dry season. Signifi cant differences were not observed regarding the frequency of visits and relative abundance among the diurnal flower visitors at both sites. In the per-visit effectiveness experiment among flower visitors, we observed one fruit produced aft er E. bombiformis' visits. Due to the complex breeding system of T. undulata in that it is characterized by very low fruit production even under natural conditions, an indirect measure of pollinator effectiveness is needed in at a future stage of this study in order to clarify the role of these bee species as pollinators of T. undulata.

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Contrasting pollination efficiency and effectiveness among flower visitors of Malva sylvestris, Borago officinalis and Onobrychis viciifolia

Journal of Pollination Ecology ◽

10.26786/1920-7603(2017)421 ◽

2017 ◽

Vol 21 ◽

Author(s):

Anna Gorenflo ◽

Tim Diekötter ◽

Mark Van Kleunen ◽

Volkmar Wolters ◽

Frank Jauker

Keyword(s):

Plant Species ◽

Pollen Deposition ◽

Pollinator Effectiveness ◽

Borago Officinalis ◽

Flower Visitor ◽

Flower Visitors ◽

Onobrychis Viciifolia ◽

Single Visit ◽

Malva Sylvestris ◽

Visitation Frequency

Biotic pollination is an important factor for ecosystem functioning and provides a substantial ecosystem service to human food security. Not all flower visitors are pollinators, however, and pollinators differ in their pollination performances. In this study, we determined the efficiencies of flower visitors to the plant species Malva sylvestris, Borago officinalis and Onobrychis viciifolia by analysing stigmatic pollen deposition. We further calculated pollinator effectiveness by scaling up single-visit pollen deposition using visitation frequency. Flower-visitor groups differed in their efficiencies at the single-visit level and not all of them deposited more pollen compared to unvisited stigmas. Bumblebees tended to be most efficient in depositing pollen per single visit across the three plant species. Due to the by far highest visitation frequencies, Apis mellifera showed the highest effectiveness in depositing pollen per hour for M. sylvestris and B. officinalis, but not for O. viciifolia, for which the Bombus lapidarius complex was both the most frequent and the most effective pollinator group. Hence, the most frequent flower visitors were most effective in our study. For non-dominant pollinator groups, however, visitation frequencies contributed disproportionally to pollinator effectiveness. Thus, combining pollen deposition per single-visit with visitation frequency is necessary to reveal true pollinator performance and to better understand flower-visitor interactions.

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Pollinator effectiveness of native and non-native flower visitors to an apparently generalist Andean shrub, Duranta mandonii (Verbenaceae)

Plant Species Biology ◽

10.1111/j.1442-1984.2011.00337.x ◽

2011 ◽

Vol 27 (2) ◽

pp. 147-158 ◽

Cited By ~ 22

Author(s):

STELLA WATTS ◽

DAVID HUAMÁN OVALLE ◽

MARCELA MORENO HERRERA ◽

JEFF OLLERTON

Keyword(s):

Pollinator Effectiveness ◽

Flower Visitors

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Experimental loss of generalist plants reveals alterations in plant-pollinator interactions and a constrained flexibility of foraging

10.1101/279430 ◽

2018 ◽

Author(s):

Paolo Biella ◽

Asma Akter ◽

Jeff Ollerton ◽

Sam Tarrant ◽

Štěpán Janeček ◽

...

Keyword(s):

Plant Traits ◽

Sugar Content ◽

Ecosystem Dynamics ◽

Pollinator Effectiveness ◽

Flower Visitor ◽

Flower Visitors ◽

Flower Visitation ◽

Key Species ◽

High Sugar Content ◽

Plant Pollinator

AbstractSpecies extinctions undermine ecosystem functioning but species do not disappear at random. Ecosystem dynamics are ruled by a subset of dominant species, but it is not clear how losing several of these key species would affect plant-pollinator interactions. We tested how the experimental loss of the most highly visited generalist plants would affect flower visitor abundances (visitation) and pollinator effectiveness (quantity of pollen-tubes within pistils) in several sites. Significant changes in the plant-pollinator communities were detected. Firstly, visitation decreased after removing 1-2 most visited plants, suggesting that these species mostly facilitate other plants by keeping high flower visitor abundances in the sites. Nevertheless, we recorded within-site variations of these trends, especially among sampled transects and among plant species, suggesting that complex facilitation-competition interactions occur among plants, but that these vary among transects within the same sites. Pollinator effectiveness fluctuated but not in a clear linear way and was not directly linked to changes of flower visitation. This suggests that fluctuations of pollinator effectiveness might be due to destabilization of the pollinators by the removal of key resources. In addition, we detected a constrained flexibility of the foraging of flower visitors because they did not switch among flower shapes and they favoured specific plant traits such as high sugar content, small inflorescences and taller plants. Indeed, these constraints would eventually limit utilisation of new resources after perturbations, possibly undermining the stability of the system. In conclusion, our work demonstrates that the loss of dominant, highly generalist plants alters plant-pollinator interactions with implications for pollination and insect foraging. Therefore, in order to preserve ecosystems, generalist plants should not get lost, because they sustain the complex pattern of interactions between plants and flower visitors.

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