The long-term decline of wild and managed insect pollinators is a threat to both agricultural output and biodiversity, and has been linked to decreasing floral resources. Further insight into the ...temporal relationships of pollinators and their flowering partners is required to inform conservation efforts. Here we examined the phenology of British: (i) pollinator activity; (ii) insect-pollinated plant flowering; and (iii) extinct and endangered pollinator and plant species. Over 1 million records were collated from the historical databases of three British insect monitoring organisations, a global biodiversity database and an authoritative text covering the national flora. Almost two-thirds (62%) of pollinator species have peak flight observations during late-summer (July and August). This was the case across three of the groups studied: aculeate wasps (71% of species), bees (60%), and butterflies (72%), the exception being hoverflies (49%). When species geographical range (a proxy for abundance) was accounted for, a clear late-summer peak was clear across all groups. By contrast, there is marked temporal partitioning in the flowering of the major plant groups: insect-pollinated tree species blossoming predominantly during May (74%), shrubs in June (69%), and herbs in July (83%). There was a positive correlation between the number of pollinator species on the wing and the richness of both flowering insect-pollinated herbs and trees/shrubs species, per calendar month. In addition, significantly greater extinctions occurred in late-summer-flying pollinator species than expected (83% of extinct species vs. 62% of all species). This trend was driven primarily by bee extinctions (80% vs. 60%) and was not apparent in other groups. We contend that this is principally due to declines in late-summer resource supplies, which are almost entirely provisioned by herbs, a consequence of historical land-use change. We hypothesize that the seasonality of interspecific competition and the blooming of trees and mass-flowering crops may have partially buffered spring-flying pollinators from the impacts of historical change.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
Background and aims
Assessing the resilience of plant–animal interactions is critical to understanding how plant communities respond to habitat disturbances. Most ecosystems experience some ...level of natural disturbance (e.g. wildfires) to which many organisms are adapted. Wildfires have structured biotic communities for millennia; however, the effects of fire on interactions such as pollination have only recently received attention. A few studies have shown that generalist plants can buffer the impact of fires by pollinator replacement, suggesting that the resilience to disturbance could depend on the level of specialization of the interactions. Here, we hypothesize that (1) fires could impose negative effects on plants with specialized pollination systems, and (2) in large wildfires, these negative effects will be stronger with increasing distance inside the burnt area because pollinators will need more time to recolonize.
Methods
These questions were tested in the specialized pollination system of a widespread Mediterranean palm, Chamaerops humilis. The post-fire pollination resilience was assessed in replicated wildfires representing three post-fire ages by measuring the abundance of beetle pollinators and by estimating fruit set (i.e. the proportion of flowers setting fruits) in burnt and unburnt areas. To test for distance effects, plants were sampled along transects inside the burnt area.
Key Results
Despite a marked post-fire decline in the specialist pollinator, exacerbated by the distance from the fire’s edge, the palm’s fruit set was barely affected. The temporary replacement by a sap beetle at burnt sites – an effective pollinator that had not been previously recognized – provided post-fire reproductive resilience.
Conclusions
Differential pollinator responses to disturbance can ensure plant success even in plants with only two functionally similar pollinators. This highlights the importance of pollinator replacement and dynamics for the resilience of interactions and ultimately of plant reproduction in disturbance-prone ecosystems.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
With many plant–pollinator interactions undergoing change as species’ distributions shift, we require a better understanding of how the addition of new interacting partners can affect plant ...reproduction. One such group of floral visitors, nectar robbers, can deplete plants of nectar rewards without contributing to pollination. The addition of nectar robbing to the floral visitor assemblage could therefore have costs to the plant´s reproductive output. We focus on a recent plant colonist, Digitalis purpurea, a plant that in its native range is rarely robbed, but experiences intense nectar robbing in areas it has been introduced to. Here, we test the costs to reproduction following experimental nectar robbing. To identify any changes in the behavior of the principal pollinators in response to nectar robbing, we measured visitation rates, visit duration, proportion of flowers visited, and rate of rejection of inflorescences. To find the effects of robbing on fitness, we used proxies for female and male components of reproductive output, by measuring the seeds produced per fruit and the pollen export, respectively. Nectar robbing significantly reduced the rate of visitation and lengths of visits by bumblebees. Additionally, bumblebees visited a lower proportion of flowers on an inflorescence that had robbed flowers. We found that flowers in the robbed treatment produced significantly fewer seeds per fruit on average but did not export fewer pollen grains. Our finding that robbing leads to reduced seed production could be due to fewer and shorter visits to flowers leading to less effective pollination. We discuss the potential consequences of new pollinator environments, such as exposure to nectar robbing, for plant reproduction.
We test whether the addition of nectar robbers into the environment of a flowering plant (Digitalis purpurea) can lead to costs for reproduction. Following experimental robbing, we found a significant decline in the visitation rate and visit duration of the bumblebee pollinators, as well as a reduction in the number of seeds produced by fruits. The addition of new floral visitors to plant systems is likely to happen more often as humans influence the ranges of plants and pollinators, and here, we show how these changes can come with costs to the reproduction of the plant.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Plants might be under selection for both attracting efficient pollinators and deterring wasteful visitors. Particular floral traits can act as exploitation barriers by discouraging the unwelcome ...visitors. In the genus
Penstemon
, evolutionary shifts from insect pollination to more efficient hummingbird pollination have occurred repeatedly, resulting in the convergent evolution of floral traits commonly present in hummingbird-pollinated flowers. Two of these traits, a reduced or reflexed lower petal lip and a narrow corolla, were found in a previous flight-cage study to affect floral handling time by bumble bees, therefore potentially acting as “anti-bee” traits affecting preference. To test whether these traits do reduce bumble bee visitation in natural populations, we manipulated these two traits in flowers of bee-pollinated
Penstemon strictus
to resemble hummingbird-adapted close relatives and measured the preferences of free-foraging bees. Constricted corollas strongly deterred bee visitation in general, and particularly reduced visits by small bumble bees, resulting in immediate specialization to larger, longer-tongued bumble bees. Bees were also deterred—albeit less strongly—by lipless flowers. However, we found no evidence that lip removal and corolla constriction interact to further affect bee preference. We conclude that narrow corolla tubes and reduced lips in hummingbird-pollinated penstemons function as exploitation barriers that reduce bee access to nectaries or increase handling time.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The seeming ubiquity of spatio-temporal variation in pollination regime suggests that flowers ought to be adapted to a wide range of pollinators, yet many comparative biologists perceive that in ...groups with complex flowers there is considerable specialization onto pollination syndromes. Statistical documentation of such syndromes has been presented for very few groups of flowers. Accordingly, we measured, for 49 species of Penstemon and close relatives, both the morphology of the flowers and visitation by pollinators. We describe the mechanics of pollination for representative species. Ordinations show a distinct difference between hummingbird-pollinated species and hymenopteran-pollinated species. Flower color is particularly good at separating hummingbird- from hymenopteran-flowers. Other characters are also correlated with this dichotomy. Within the hymenopteran-pollinated species, there are additional relationships between floral morphology and the size of the principal pollinators. Flowers frequented by large bees, such as Xylocopa, have large open vestibules and relatively short floral tubes. Flowers frequented by smaller bees, such as Osmia, have long narrow floral tubes. Unlike nectar-collecting bees, pollen-collecting bees tend to be attracted to flowers of the hummingbird syndrome. The overarching pattern was that syndrome characterizations were successful at predicting pollination by hummingbirds versus Hymenoptera, two types of animals that are profoundly different, but less successful at predicting visitation by one kind of bee versus another.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Male‐male competition in plants is thought to exert selection on flower morphology and on the temporal presentation of pollen. Theory suggests that a plant’s pollen dosing strategy should evolve to ...match the abundance and pollen transfer efficiency of its pollinators. Simultaneous pollen presentation should be favored when pollinators are infrequent or efficient at delivering the pollen they remove, whereas gradual dosing should optimize delivery by frequent and wasteful pollinators. AmongPenstemonandKeckiellaspecies, anthers vary in ways that affect pollen release, and the morphology of dried anthers reliably indicates how they dispense pollen. In these genera, hummingbird pollination has evolved repeatedly from hymenopteran pollination. Pollen production does not change with evolutionary shifts between pollinators. We show that after we control for phylogeny, hymenopteran‐adapted species present their pollen more gradually than hummingbird‐adapted relatives. In a species pair that seemed to defy the pattern, the rhythm of anther maturation produced an equivalent dosing effect. These results accord with previous findings that hummingbirds can be more efficient than bees at delivering pollen.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
After two decades of meta-analyses on plant traits, we can now look for global emergent patterns in plant evolutionary ecology. Hundreds of meta-analyses have focused on the effects of specific ...selection pressures on plant fitness, and the buildup of such results allows us to ask general questions regarding selection pressures and plant responses, a major focus of evolutionary ecology. Plant traits are affected by both abiotic and biotic factors. For example, biotic pressures like herbivory may affect physiological (i.e. secondary defences) and reproductive (i.e. seed predation) traits. Similarly, abiotic pressures such as increased CO
2
may affect both plant physiology and reproduction. We tested whether biotic or abiotic selective pressures are more important for plant traits, and if the strength of the response to those pressures depends on the plant trait studied by meta-analyzing published meta-analyses on plant responses. We classify meta-analyses according to the type of response variable studied (fitness and non-fitness traits) and the type of selective pressure examined (biotic or abiotic). Our database showed biases in the meta-analysis literature, for example that the majority of studies are focused on non-fitness traits, i.e. on traits that are not directly related to reproduction or survival, and furthermore, on non-fitness traits under abiotic selection pressures. The meta-meta-analysis showed that the strength of responses to selection depends on the nature of selection (stronger for biotic than for abiotic factors) but, unexpectedly, not on the type of trait under study as previously found. The stronger responses to biotic factors can be explained if biotic selection is more variable in space and time, driven by interactions with other organisms. The relative importance of biotic versus abiotic factors on plant traits has been little studied in the past, and would benefit from more studies and reviews that fill the under-represented combinations of selective pressures and plant traits (i.e. abiotic factors on fitness traits).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Summary
Plants can evolve rapidly after pollinator changes, but the response of different floral traits to novel selection can vary. Floral morphology is often expected to show high integration to ...maintain pollination accuracy, while nectar traits can be more environmentally sensitive. The relative role of genetic correlations and phenotypic plasticity (PP) in floral evolution remains unclear, particularly for nectar traits, and can be studied in the context of recent pollinator changes.
Digitalis purpurea shows rapid recent evolution of corolla morphology but not nectar traits following a range expansion with hummingbirds added as pollinators. We use this species to compare PP, heritability, evolvability and integration of floral morphology and nectar in a common garden.
Morphological traits showed higher heritability than nectar traits, and the proximal section of the corolla, which regulates access to nectar and underwent rapid change in introduced populations, presented lower integration than the rest of the floral phenotype. Nectar was more plastic than morphology, driven by highly plastic sugar concentration. Nectar production rate showed high potential to respond to selection.
These results explain the differential rapid evolution of floral traits previously observed in this species and show how intrafloral modularity determines variable evolutionary potential in morphological and nectar traits.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Introduction. The aim of the present study was to determine the effects of vitamins D and E on the proliferation, morphology, and differentiation of human dental pulp stem cells (hDPSCs). Methods. In ...this in vitro experimental study, hDPSCs were isolated, characterized, and treated with vitamins D and E, individually and in combination, utilizing different doses and treatment periods. Changes in morphology and cell proliferation were evaluated using light microscopy and the resazurin assay, respectively. Osteoblast differentiation was evaluated with alizarin red S staining and expression of RUNX2, Osterix, and Osteocalcin genes using real-time RT-PCR. Results. Compared with untreated cells, the number of cells significantly reduced following treatment with vitamin D (49%), vitamin E (35%), and vitamins D + E (61%) after 144 h. Compared with cell cultures treated with individual vitamins, cells treated with vitamins D + E demonstrated decreased cell confluence, with more extensive and flatter cytoplasm that initiated the formation of a significantly large number of calcified nodules after 7 days of treatment. After 14 days, treatment with vitamins D, E, and D + E increased the transcription of RUNX2, Osterix, and Osteocalcin genes. Conclusions. Vitamins D and E induced osteoblastic differentiation of hDPSCs, as evidenced by the decrease in cell proliferation, morphological changes, and the formation of calcified nodules, increasing the expression of differentiation genes. Concurrent treatment with vitamins D + E induces a synergistic effect in differentiation toward an osteoblastic lineage.
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CMK, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
OBJETIVO: Analisar a acessibilidade de famílias negras de bairro popular aos serviços de atenção básica à saúde. MÉTODOS: Estudo etnográfico, ancorado na antropologia de base interpretativa, ...realizado com 18 famílias selecionadas de um bairro popular de Salvador, BA, no período de dois anos. Os critérios de inclusão foram residência no bairro e autoclassificação como negros. A análise se baseou na antropologia interpretativa e considerou as categorias: autorreferência étnico-racial; experiências de discriminação nos serviços; percepção sobre acessibilidade na atenção básica; e barreiras de acessibilidade. RESULTADOS E DISCUSSÃO: Identificaram-se os seguintes aspectos: a) identidade étnico-racial e saúde: percepção dos usuários de que as barreiras organizacionais e de acesso se devem a um amplo contexto social que produz cidadãos "de primeira e de segunda categorias", mais do que a um racismo institucional; b) acessibilidade no Sistema Único de Saúde (SUS): acesso problemático, permeado pela demora no atendimento, falta de compromisso dos profissionais de saúde, omissão dos gestores no controle e correção dessas situações; c) acessibilidade na atenção básica: visão sobre o contexto mais geral do SUS e apoio na descrição dos entrevistados sobre o acesso aos serviços de atenção básica. CONCLUSÕES: Há barreiras de acessibilidade econômicas, organizacionais e culturais que se interpõem entre a oferta de serviços e o atendimento efetivo e oportuno das necessidades da população estudada.
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