scholarly journals Constructing more informative plant–pollinator networks: visitation and pollen deposition networks in a heathland plant community

2015 ◽  
Vol 282 (1814) ◽  
pp. 20151130 ◽  
Author(s):  
G. Ballantyne ◽  
Katherine C. R. Baldock ◽  
P. G. Willmer
Keyword(s):  
Food Security ◽  
Plant Community ◽  
Interaction Networks ◽  
Pollen Deposition ◽  
Pollinator Effectiveness ◽  
Pollinator Importance ◽  
Visit Frequency ◽  
Low Diversity ◽  
Pollination Systems ◽  
Plant Pollinator

Interaction networks are widely used as tools to understand plant–pollinator communities, and to examine potential threats to plant diversity and food security if the ecosystem service provided by pollinating animals declines. However, most networks to date are based on recording visits to flowers, rather than recording clearly defined effective pollination events. Here we provide the first networks that explicitly incorporate measures of pollinator effectiveness (PE) from pollen deposition on stigmas per visit, and pollinator importance (PI) as the product of PE and visit frequency. These more informative networks, here produced for a low diversity heathland habitat, reveal that plant–pollinator interactions are more specialized than shown in most previous studies. At the studied site, the specialization index was lower for the visitation network than the PE network, which was in turn lower than for the PI network. Our study shows that collecting PE data is feasible for community-level studies in low diversity communities and that including information about PE can change the structure of interaction networks. This could have important consequences for our understanding of threats to pollination systems.

scholarly journals Pollinator importance networks illustrate the crucial value of bees in a highly speciose plant community

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Gavin Ballantyne ◽  
Katherine C. R. Baldock ◽  
Luke Rendell ◽  
P. G. Willmer
Keyword(s):  
Plant Species ◽  
Community Level ◽  
Taxonomic Resolution ◽  
Pollen Deposition ◽  
Pollinator Effectiveness ◽  
Flower Visitors ◽  
Pollinator Importance ◽  
Visitation Frequency ◽  
Pollinator Performance ◽  
Number Of Plant Species

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.

scholarly journals The worldwide importance of honey bees as pollinators in natural habitats

2018 ◽  
Vol 285 (1870) ◽  
pp. 20172140 ◽  
Author(s):  
Keng-Lou James Hung ◽  
Jennifer M. Kingston ◽  
Matthias Albrecht ◽  
David A. Holway ◽  
Joshua R. Kohn
Keyword(s):  
Apis Mellifera ◽  
Plant Species ◽  
Honey Bees ◽  
Interaction Networks ◽  
Flowering Plant ◽  
Pollinator Effectiveness ◽  
Natural Habitats ◽  
Floral Visitor ◽  
Native And Introduced Ranges ◽  
Plant Pollinator

The western honey bee ( Apis mellifera ) is the most frequent floral visitor of crops worldwide, but quantitative knowledge of its role as a pollinator outside of managed habitats is largely lacking. Here we use a global dataset of 80 published plant–pollinator interaction networks as well as pollinator effectiveness measures from 34 plant species to assess the importance of A. mellifera in natural habitats. Apis mellifera is the most frequent floral visitor in natural habitats worldwide, averaging 13% of floral visits across all networks (range 0–85%), with 5% of plant species recorded as being exclusively visited by A. mellifera . For 33% of the networks and 49% of plant species, however, A. mellifera visitation was never observed, illustrating that many flowering plant taxa and assemblages remain dependent on non- A. mellifera visitors for pollination. Apis mellifera visitation was higher in warmer, less variable climates and on mainland rather than island sites, but did not differ between its native and introduced ranges. With respect to single-visit pollination effectiveness, A. mellifera did not differ from the average non- A. mellifera floral visitor, though it was generally less effective than the most effective non- A. mellifera visitor. Our results argue for a deeper understanding of how A. mellifera , and potential future changes in its range and abundance, shape the ecology, evolution, and conservation of plants, pollinators, and their interactions in natural habitats.

Disrupting plant-pollinator systems endangers food security

One Earth ◽  
2021 ◽  
Vol 4 (9) ◽  
pp. 1217-1219
Author(s):  
Teja Tscharntke
Keyword(s):  
Food Security ◽  
Plant Pollinator

scholarly journals How can an understanding of plant–pollinator interactions contribute to global food security?

2015 ◽  
Vol 26 ◽  
pp. 72-79 ◽  
Author(s):  
Emily J Bailes ◽  
Jeff Ollerton ◽  
Jonathan G Pattrick ◽  
Beverley J Glover
Keyword(s):  
Food Security ◽  
Global Food Security ◽  
Plant Pollinator ◽  
Global Food

Heterospecific pollen deposition is positively associated with reproductive success in a diverse hummingbird‐pollinated plant community

Oikos ◽  
2021 ◽  
Author(s):  
Sabrina Aparecida Lopes ◽  
Pedro Joaquim Bergamo ◽  
Steffani Najara Pinho Queiroz ◽  
Jeff Ollerton ◽  
Thiago Santos ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Plant Community ◽  
Pollen Deposition ◽  
Heterospecific Pollen ◽  
Heterospecific Pollen Deposition

Predator Effects on Plant-Pollinator Interactions, Plant Reproduction, Mating Systems, and Evolution

2020 ◽  
Vol 51 (1) ◽  
pp. 319-340
Author(s):  
Amanda D. Benoit ◽  
Susan Kalisz
Keyword(s):  
Mating Systems ◽  
Seed Set ◽  
Pollen Limitation ◽  
Plant Traits ◽  
Plant Reproduction ◽  
Trophic Levels ◽  
Interaction Networks ◽  
Pollinator Abundance ◽  
Plant Pollinator ◽  
Predator Effects

Plants are the foundation of the food web and therefore interact directly and indirectly with myriad organisms at higher trophic levels. They directly provide nourishment to mutualistic and antagonistic primary consumers (e.g., pollinators and herbivores), which in turn are consumed by predators. These interactions produce cascading indirect effects on plants (either trait-mediated or density-mediated). We review how predators affect plant-pollinator interactions and thus how predators indirectly affect plant reproduction, fitness, mating systems, and trait evolution. Predators can influence pollinator abundance and foraging behavior. In many cases, predators cause pollinators to visit plants less frequently and for shorter durations. This decline in visitation can lead to pollen limitation and decreased seed set. However, alternative outcomes can result due to differences in predator, pollinator, and plant functional traits as well as due to altered interaction networks with plant enemies. Furthermore, predators may indirectly affect the evolution of plant traits and mating systems.

scholarly journals Linking pollinator efficiency to patterns of pollen limitation: small bees exploit the plant–pollinator mutualism

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180635 ◽  
Author(s):  
Matthew H. Koski ◽  
Jennifer L. Ison ◽  
Ashley Padilla ◽  
Angela Q. Pham ◽  
Laura F. Galloway
Keyword(s):  
Pollen Limitation ◽  
Pollen Deposition ◽  
Pollinator Efficiency ◽  
Flower Visitation ◽  
Female Phase ◽  
Male Phase ◽  
Single Flower ◽  
Floral Visitation ◽  
Low Efficiency ◽  
Plant Pollinator

Seemingly mutualistic relationships can be exploited, in some cases reducing fitness of the exploited species. In plants, the insufficient receipt of pollen limits reproduction. While infrequent pollination commonly underlies pollen limitation (PL), frequent interactions with low-efficiency, exploitative pollinators may also cause PL. In the widespread protandrous herb Campanula americana , visitation by three pollinators explained 63% of the variation in PL among populations spanning the range. Bumblebees and the medium-sized Megachile campanulae enhanced reproductive success, but small solitary bees exacerbated PL. To dissect mechanisms behind these relationships, we scored sex-specific floral visitation, and the contributions of each pollinator to plant fitness using single flower visits. Small bees and M. campanulae overvisited male-phase flowers, but bumblebees frequently visited female-phase flowers. Fewer bumblebee visits were required to saturate seed set compared to other bees. Scaling pollinator efficiency metrics to populations, small bees deplete large amounts of pollen due to highly male-biased flower visitation and infrequent pollen deposition. Thus, small bees reduce plant reproduction by limiting pollen available for transfer by efficient pollinators, and appear to exploit the plant–pollinator mutualism, acting as functional parasites to C. americana . It is therefore unlikely that small bees will compensate for reproductive failure in C. americana when bumblebees are scarce.

scholarly journals A novel perspective on the meaning of nestedness with conceptual and methodological solutions

2021 ◽  
Author(s):  
Rafael Barros Pereira Pinheiro ◽  
Carsten F. Dormann ◽  
Gabriel Moreira Felix ◽  
Marco A. R. Mello
Keyword(s):  
Null Model ◽  
Interaction Network ◽  
Species Interaction ◽  
Null Models ◽  
Interaction Networks ◽  
Common Pattern ◽  
Expected Values ◽  
New Perspective ◽  
Test Outcomes ◽  
Plant Pollinator

Aim: Nestedness is a common pattern in metacommunities and interaction networks, whose causes are still discussed. Nestedness inference is challenging because, beyond calculating an index, we need to compare observed values with values generated with a null model. There are different null models and the choice between them affects test outcomes. Furthermore, there is no established theoretical basis to guide this choice. Here, we propose a different look at the meaning of nestedness that improves our understanding of its causes and unveils the link between null models and hypotheses. Innovation: Nestedness of a matrix is a combination of marginal sum inequality and high overlap. The higher the overlap, the more predictable the cell values by marginal sums. Here, we show that nestedness actually measures how better one can predict cell values by marginal sums than by matrix dimensions and total sum alone. From this, we propose that two null models can be used to test for different topological hypotheses. The equiprobable model excludes all nestedness-generating mechanisms and provides the distribution of expected values for nestedness significance tests. The proportional model conserves nestedness-generating mechanisms and excludes nestedness-disrupting mechanisms, and thus, produces highly nested matrices. The proportional model provides the distribution of expected nestedness for nested matrices. Additionally, we evaluate the efficiency of several indices within this new perspective and illustrate our approach using an empirical plant-pollinator network. Main conclusions: Through a shift of perspective, our approach reconciliates contradictions in null model analysis and delimits the range of possible explanations for nestedness. The only way a process can increase nestedness in a matrix is by promoting marginal sum inequalities, without concomitantly introducing preferences. Consequently, in a species interaction network, explanations for nestedness should explain why some species interact more frequently than others.

scholarly journals The effect of landscape on Cucurbita pepo-pollinator interaction networks varies depending on plants’ genetic diversity

2021 ◽  
Author(s):  
Patricia Landaverde-González ◽  
Eunice Enríquez ◽  
Juan Núñez-Farfán
Keyword(s):  
Genetic Diversity ◽  
Land Use ◽  
Network Structure ◽  
Cucurbita Pepo ◽  
Interaction Network ◽  
Network Evolution ◽  
Interaction Networks ◽  
Pollinator Community ◽  
Male Flowers ◽  
Plant Pollinator

AbstractIn recent years, evidence has been found that plant-pollinator interactions are altered by land-use and that genetic diversity also plays a role. However, how land-use and genetic diversity influence plant–pollinator interactions, particularly in the Neotropics, where many endemic plants exist is still an open question. Cucurbita pepo is a monoecious plant and traditional crop wide distributed, with high rates of molecular evolution, landraces associated with human cultural management and a history of coevolution with bees, which makes this species a promising model for studying the effect of landscape and genetic diversity on plant-pollinator interactions. Here, we assess (1) whether female and male flowers differences have an effect on the interaction network, (2) how C. pepo genetic diversity affects flower-bee visitation network structure, and (3) what is the effect that land-use, accounting for C. pepo genetic variability, has on pumpkin-bee interaction network structure. Our results indicate that female and male flowers presented the same pollinator community composition and interaction network structure suggesting that female/male differences do not have a significant effect on network evolution. Genetic diversity has a positive effect on modularity, nestedness and number of interactions. Further, the effect of semi-natural areas on nestedness could be buffered when genetic diversity is high. Our results suggest that considering genetic diversity is relevant for a better understanding of the effect of land-use on interaction networks. Additionally, this understanding has great value in conserving biodiversity and enhancing the stability of interaction networks in a world facing great challenges of habitat and diversity loss.

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