scholarly journals The effects of experimental floral resource removal on plant-pollinator interactions

2021 ◽  
Author(s):  
Justin A. Bain ◽  
Rachel G. Dickson ◽  
Andrea M. Gruver ◽  
Paul J. CaraDonna
Keyword(s):  
Network Structure ◽  
Species Turnover ◽  
Individual Species ◽  
Natural Setting ◽  
Species Loss ◽  
Pollinator Visitation ◽  
Local Loss ◽  
Visitation Rates ◽  
Floral Visitor ◽  
Plant Pollinator

AbstractPollination is essential for ecosystem functioning, yet our understanding of the empirical consequences of species loss for plant-pollinator interactions remains limited. It is hypothesized that the loss of abundant and generalized (well-connected) species from a pollination network will have a large effect on the remaining species and their interactions. However, to date, relatively few studies have experimentally removed species from their natural setting to address this hypothesis. We investigated the consequences of losing an abundant, well-linked species from a series of plant-pollinator networks by experimentally removing the flowers of Helianthella quinquenervis (Asteraceae) from half of a series of 10 paired plots (15 m diameter) within a subalpine ecosystem. We then asked how the localized loss of this species influenced pollinator visitation patterns, floral visitor composition, and interaction network structure. The experimental removal of Helianthella flowers led to an overall decline in plot-level pollinator visitation rates and shifts in pollinator composition. Species-level responses to floral removal differed between the two other abundant, co-flowering plants in our experiment: Potentilla pulcherrima received higher visitation rates, whereas Erigeron speciosus visitation rates did not change. Experimental floral removal altered the structural properties of the localized plant-pollinator networks such that they were more specialized, less nested, and less robust to further species loss. Such changes to interaction structure were consistently driven more by species turnover than by interaction rewiring. Our findings suggest that the local loss of an abundant, well-linked, generalist plant can bring about diverse responses within pollination networks, including potential competitive and facilitative effects for individual species, changes to network structure that may render them more sensitive to future change, but also numerous changes to interactions that may also suggest flexibility in response to species loss.

scholarly journals On the temporally flexible structure of plant-pollinator interaction networks

2020 ◽  
Author(s):  
Paul J. CaraDonna ◽  
Nickolas M. Waser
Keyword(s):  
Temporal Variation ◽  
Network Structure ◽  
Species Interactions ◽  
Interspecific Interactions ◽  
Activity Period ◽  
Individual Species ◽  
Ecological Communities ◽  
Short Term ◽  
Temporal Flexibility ◽  
Plant Pollinator

AbstractEcological communities consist of species that are joined in complex networks of interspecific interaction. The interactions that networks depict often form and dissolve rapidly, but this temporal variation is not well integrated into our understanding of the causes and consequences of network structure. If interspecific interactions exhibit temporal flexibility across time periods over which organisms co-occur, then the emergent structure of the corresponding network may also be temporally flexible, something that a temporally-static perspective would miss. Here, we use an empirical system to examine short-term flexibility in network structure (connectance, nestedness, and specialization), and in individual species interactions that contribute to that structure. We investigated weekly plant-pollinator networks in a subalpine ecosystem across three summer growing seasons. To link the interactions of individual species to properties of their networks, we examined weekly temporal variation in species’ contributions to network structure. As a test of the potential robustness of networks to perturbation, we also simulated the random loss of species from weekly networks. We then compared the properties of weekly networks to the properties of cumulative networks that aggregate field observations over each full season. A week-to-week view reveals considerable flexibility in the interactions of individual species and their contributions to network structure. For example, species that would be considered relatively generalized across their entire activity period may be much more specialized at certain times, and at no point as generalized as the cumulative network may suggest. Furthermore, a week-to-week view reveals corresponding temporal flexibility in network structure and potential robustness throughout each summer growing season. We conclude that short-term flexibility in species interactions leads to short-term variation in network properties, and that a season-long, cumulative perspective may miss important aspects of the way in which species interact, with implications for understanding their ecology, evolution, and conservation.

scholarly journals Insectivorous bats are less active near freeways

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247400
Author(s):  
Manisha Bhardwaj ◽  
Kylie Soanes ◽  
José J. Lahoz-Monfort ◽  
Linda F. Lumsden ◽  
Rodney van der Ree
Keyword(s):  
Agricultural Landscapes ◽  
Individual Species ◽  
Insectivorous Bats ◽  
Predator Prey ◽  
The Road ◽  
Environmental Impact Assessments ◽  
Wildlife Populations ◽  
Roadside Verges ◽  
The Impact ◽  
Plant Pollinator

Traffic disturbances (i.e. pollution, light, noise, and vibrations) often extend into the area surrounding a road creating a ‘road-effect zone’. Habitat within the road-effect zone is degraded or, in severe cases, completely unsuitable for wildlife, resulting in indirect habitat loss. This can have a disproportionate impact on wildlife in highly modified landscapes, where remaining habitat is scarce or occurs predominantly along roadside reserves. In this study, we investigated the road-effect zone for insectivorous bats in highly cleared agricultural landscapes by quantifying the change in call activity with proximity to three major freeways. The activity of seven out of 10 species of bat significantly decreased with proximity to the freeway. We defined the road-effect zone to be the proximity at which call activity declined by at least 20% relative to the maximum detected activity. The overall road-effect zone for bats in this region was 307 m, varying between 123 and 890 m for individual species. Given that this road-effect zone exceeds the typical width of the roadside verges (<50 m), it is possible that much of the vegetation adjacent to freeways in this and similar landscapes provides low-quality habitat for bats. Without accounting for the road-effect zone, the amount of habitat lost or degraded due to roads is underestimated, potentially resulting in the loss of wildlife, ecosystem services and key ecosystem processes (e.g. predator-prey or plant-pollinator interactions) from the landscape. We suggest all future environmental impact assessments include quantifying the road-effect zone for sensitive wildlife, in order to best plan and mitigate the impact of roads on the environment. Mitigating the effects of new and existing roads on wildlife is essential to ensure enough high-quality habitat persists to maintain wildlife populations.

scholarly journals Reconstruction of plant–pollinator networks from observational data

2019 ◽  
Author(s):  
Jean-Gabriel Young ◽  
Fernanda S. Valdovinos ◽  
M. E. J. Newman
Keyword(s):  
Food Webs ◽  
Observational Data ◽  
Network Structure ◽  
Rare Species ◽  
Statistical Technique ◽  
Ecological Networks ◽  
Statistical Analyses ◽  
Published Data ◽  
Statistical Errors ◽  
Plant Pollinator

Empirical measurements of ecological networks such as food webs and mutualistic networks are often rich in structure but also noisy and error-prone, particularly for rare species for which observations are sparse. Focusing on the case of plant–pollinator networks, we here describe a Bayesian statistical technique that allows us to make accurate estimates of network structure and ecological metrics from such noisy observational data. Our method yields not only estimates of these quantities, but also estimates of their statistical errors, paving the way for principled statistical analyses of ecological variables and outcomes. We demonstrate the use of the method with an application to previously published data on plant–pollinator networks in the Seychelles archipelago, calculating estimates of network structure, network nestedness, and other characteristics.

scholarly journals Plant-pollinator interactions in Crambe abyssinicaHochst. (Brassicaceae) associated with environmental variables

2015 ◽  
Vol 87 (1) ◽  
pp. 137-145 ◽  
Author(s):  
Lívia C. Simioni ◽  
Rosilda M. Mussury ◽  
Munir Mauad ◽  
Daiane M. Dresh ◽  
Fabricio F. Pereira ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Environmental Variables ◽  
Insect Pests ◽  
Economic Importance ◽  
Alternative Methods ◽  
Regression Equations ◽  
Weekly Basis ◽  
Pollinator Visitation ◽  
Crambe Abyssinica ◽  
Plant Pollinator

Despite the economic importance of Crambe abyssinica, the present study is the first report on bees that occur with this species, and could aid in developing alternative methods for controlling insect pests without seriously impacting pollinators. The present study examined the following questions: (1) Which species are potential pollinators of C. abyssinica? (2) How do environmental conditions influence pollinator visitation fluctuations? Insects were sampled on a weekly basis between 08:00 and 16:00 during five weeks of flowering. When the results of analyses of variance were significant, the data was adjusted using regression equations at a 5% level of probability; the environmental variables were examined using Pearson's correlation coefficient. Apis mellifera, Geotrigona mombuca, Exomalopsis (Exomalopsis) fulvofasciata, Plebeia sp. and Dialictus sp. were observed visiting C. abyssinica flowers. A. melliferaand G. mombucawere observed to be potential pollinators, with the former demonstrating visitation peaks during flowering weeks II and IV at 12:00 and 08:00, respectively and the latter visiting during weeks III and IV at 12:00 and 10:00, respectively. Environmental factors such as temperature, relative humidity, and wind speed have different effect on the activity of bees.

scholarly journals Paddy fields located in water storage zones could take over the wetland plant community

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Takeshi Osawa ◽  
Takaaki Nishida ◽  
Takashi Oka
Keyword(s):  
Land Use ◽  
Plant Community ◽  
Community Assembly ◽  
Human Activities ◽  
Species Turnover ◽  
Paddy Fields ◽  
Species Loss ◽  
Habitat Conditions ◽  
Multi Temporal ◽  
Original Habitat

Abstract Land use change could affect not only local species richness but also community assemblies. Essentially, the possible patterns of plant community assemblies are nonrandom species loss (nestedness) and species turnover. Plant community assemblies in human-mediated land use have a combination of both nestedness and turnover. This is because of historical effects that cause nonrandom species loss due to previous and/or original habitat quality and because of direct effects of human activities that cause species turnover. We investigated the complexity of the process of plant community assemblage in a paddy field, which is a typical agricultural land use in the monsoon season in central Japan. Using multi-temporal plant monitoring records, we tested the relationship between the ratio of species nestedness/turnover through multi-temporal and both the original habitat conditions and the extent of human modification. The findings revealed that paddy fields that originated from wetland habitat had a high nestedness ratio, whereas paddy fields that were largely consolidated had a high turnover ratio. Thus, we could divide the community assembly processes in human-mediated land use based on original habitat conditions and human activities. This concept could help land managers establish conservation and/or restoration plans that take into account community assembly.

scholarly journals The factors influencing the pollinators visitation of the oilseed rape cultivars

2019 ◽  
Vol 65 (No. 12) ◽  
pp. 574-580
Author(s):  
Jan Kazda ◽  
Aneta Bokšová ◽  
Martina Stejskalová ◽  
Tomáš Šubrt ◽  
Jan Bartoška ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Oilseed Rape ◽  
Honey Bees ◽  
Bumble Bees ◽  
Major Influence ◽  
Winter Oilseed Rape ◽  
Pollinator Visitation ◽  
Factors Influencing ◽  
Visitation Rates ◽  
The Individual

Currently, the hybrid cultivars are predominant in the cultivation of winter oilseed rape in Europe. Cultivation of hybrid cultivars instead of the traditional line can affect the visitation of pollinators. Beekeepers and farmers claim that hybrid cultivars are not visited by pollinators as much as the line. Ten yellow and one white flowering oilseed rape cultivars were used to compare the visitation rates of pollinators (Apis mellifera L. and Bombus sp.) during flowering in the years 2015–2017. At the same time, the visitation of hybrid and line cultivars by pollinators was evaluated. Visitation of pollinators on each cultivar was calculated from observed visitations to flowering oilseed rape plants in an area 2.1 m<sup>2</sup> from the edge of single plots for 20 s. The results from this study clearly show that the individual cultivars, whether hybrids or lines, did not have a major influence on the pollinators’ visitation, either by honey bees or bumble bees. It is thus proved that hybrid cultivars do not affect the pollinator visitation and there is no need to worry about the prevalence of these cultivars in the Czech fields. However, a more significant effect for both pollinator groups appears to have been the color of the flower.

scholarly journals Threatened bryophytes of the neotropical rain forest: a status report

1992 ◽  
Vol 6 (1) ◽  
pp. 83-93 ◽  
Author(s):  
S. Rob Gradstein
Keyword(s):  
Rain Forest ◽  
Southeastern Brazil ◽  
Status Report ◽  
Greater Antilles ◽  
Species Loss ◽  
Rain Forests ◽  
Local Loss ◽  
Critical Areas ◽  
Neotropical Rain Forest ◽  
Threatened Bryophytes

Tropical deforestation, inevitably, leads to the local loss of bryophyte species. Recent studies show that the degree of species loss may vary considerably and depends on the scale or amount of habitat change that has occurred. Predictably, the shade epiphytes are most seriously affected by disturbance. An estimated 10% of the bryophyte species of neotropical rain forests are under threat. Based on data from recent monographs, a first list of 19 endangered and 27 rare species of these forests is presented. Critical areas for threatened species include Costa Rica and Panama, the Greater Antilles, the Chocó, southeastern Brazil, and parts of Amazonia. Protection of as much as possible of the remaining natural rain forest area seems the best approach to the conservation of the tropical bryophyte flora.

scholarly journals Impact of Urbanization to an Island and the Continent: Species Turnover and Nestedness in Neotropical Bird Assemblages

2021 ◽  
Vol 9 ◽  
Author(s):  
Sabina A. Caula ◽  
Virginia Sanz D'Angelo
Keyword(s):  
Negative Impact ◽  
Species Turnover ◽  
Bird Species ◽  
Urban Environments ◽  
Individual Species ◽  
Similar Species ◽  
Urban Gradient ◽  
Building Density ◽  
Urbanized Areas ◽  
Urban Matrix

Islands are well-known as particular and vulnerable ecosystems with evolutionary histories, environmental characteristics, and original communities different from those of continents. On the contrary, urban environments are recent, artificial, and structurally similar among distant regions. To assess the relative importance of regional and local processes on urban biota, we chose two urban environments, i.e., one on the mainland and another on an island in the same ecoregion. We asked whether the urbanization process affects the avian biodiversity of the ISLAND in the same way as in the continent. We defined an urban gradient with three levels of building density, namely, patches of native vegetation (remnant woodlands in the urban matrix), medium density urbanized areas that maintain vegetation along the streets and gardens, and residential areas with less vegetation cover and higher building density. In each geographical locality, we selected three sites (replicates) for each level of the urban gradient and did bird surveys. We found two times as many species in the urban landscape of the continent (69) as on the island (35), with the analogous richness decrease along the gradient in both regions. Species similarity was higher between urbanized sites of both regions compared with the similarity between woodlands and urbanized sites, showing that urban matrix filters similar species of each pool regionally. Individual species responded to urban structure in different ways. We found 32% of bird species were urban exploiters, 48% urban tolerant, and 20% urban avoiders in both regions. However, some species showed different frequencies of occurrence on the island and the continent. Species turnover contributed more than richness differences to species dissimilarity along the urban gradient on the continent. Contrarily, the nestedness component (i.e., species being a strict subset of the species at a richer site) was higher on the island. We concluded that the negative impact of highly urbanized areas on birds was stronger on the island than on the continent. Our results may help to assess the implications of beta-diversity loss, especially on islands.

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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