477 research outputs found
Ecology of flowering and fruiting in Lotus corniculatus L.
Lotus corniculatus L. (Legtuninosae), is a perennial herb common throughout Britain. Its main pollinators are bumblebees (Bombus spp., Apidae: Hymenoptera). This is a study of the ecological factors which are important to flowering and fruiting in the species, and some of their evolutionary implications. The work was carried out at Wytham Estate, Oxfordshire, U.K., mainly in an ex-arable field (Upper Seeds) and a more established grassland (Lower Seeds Reserve).
The literature on self-incompatibility in L. corniculatus is reviewed; there are conflicting reports, but wild material is fundamentally self-incompatible.
Plants in Upper Seeds are larger than in Lower Seeds Reserve. Comparative data on soil nutrients in the two sites suggests that the cause is the persistence of phosphorus from inorganic fertiliser.
There is a positive, linear relationship between plant size, flower production and fruit production. The species regulates investment in flowers mainly at the level of the whole inflorescence, rather
than altering number of flowers per inflorescence. Within individuals, there are no consistent trade-offs between number of fruit per infructescence, numbers of seeds per fruit and seed weight.
Weather patterns only partially explain the flowering phenology of L. corniculatus. Timing of first flowering and peak flowering are correlated but are variable between individuals, and between years for the same individuals. They are not correlated with flowering synchrony. An individual's flowering pattern does not consistently affect fruit-set; the overriding determinant of fruit production is plant size. Selection is therefore unlikely to be acting on flowering time in this species.
The production of large numbers of self-incompatible flowers does not seem to reduce fruit-set; pollinators do not visit enough flowers per foraging trip (perhaps because nectar production is low) for geitonogamy to become a problem.
Seed predation by larvae of a chalcid wasp, a weevil and a moth differs between individual plants, but not consistently so between years. Seed predation is not consistently correlated with plant size, mean flowers per inflorescence, number of seeds per fruit or seed size. There is no evidence for selection acting on these traits through seed predation. Partially predated seeds are often viable, which may have implications for seedling demography. Seed predation and flowering phenology are not defmitively linked, strengthening the argument that flowering time is not adaptive in this species
Extinctions of aculeate pollinators in Britain and the role of large-scale agricultural changes
Pollinators are fundamental to maintaining both biodiversity and agricultural productivity, but habitat destruction, loss of flower resources, and increased use of pesticides are causing declines in their abundance and diversity. Using historical records we assessed the rate of extinction of bee and flower-visiting wasp species in Britain, from the mid 19th century to the present. The most rapid phase of extinction appears to be related to changes in agricultural policy and practice beginning in the 1920s, before the agricultural intensification prompted by the Second World War, often cited as the most important driver of biodiversity loss in Britain. Slowing of the extinction rate from the 1960s onwards may be due to prior loss of the most sensitive species and/or effective conservation programs
The macroecology of animal versus wind pollination: ecological factors are more important than historical climate stability
Background: The relative frequency of wind and animal pollinated plants is non-randomly distributed across the globe and numerous hypotheses have been raised for the greater occurrence of wind pollination in some habitats and towards higher latitudes. To date, however, there has been no comprehensive global investigation of these hypotheses. Aims: Investigating a range of hypotheses for the role of biotic and abiotic factors as determinants of the global variation in animal versus wind pollination. Methods: We analysed 67 plant communities ranging from 70Âş North to 34Âş South. For these we determined habitat type, species richness, insularity, topographic heterogeneity, current climate and Late-Quaternary climate change. The predictive effects of these factors on the proportion of wind- and animal-pollinated plants were tested using correlations, ordinary least squares (OLS) and logistic regression analyses with information-theoretic model selection. Results: The proportion of animal-pollinated plant species was positively associated with plant species richness and current temperature. Furthermore, in forest, animal pollination was positively related to precipitation. Historical climate was only weakly and idiosyncratically correlated with animal pollination. Conclusion: Results were consistent with the hypothesised reduced chance for wind-transported pollen reaching conspecific flowers in species-rich communities, fewer constraints on nectar production in warm and wet habitats, and reduced relative effectiveness of wind dispersal in humid areas. There was little evidence of a legacy of historical climate change affecting these patterns
Mission in a Welsh Context: Patterns of Nonconformist Mission in Wales and the Challenge of Contextualisation in the Twenty First Century
This thesis considers aspects of contextualisation in the mission of local churches in twenty-first century Wales. Welsh Nonconformity rose rapidly to a dominant position in Welsh society and culture in the nineteenth century, but has subsequently declined equally rapidly. By the beginning of the twenty-first century its total demise is predicted. The research examines the contextual factors in this decline, and their relevance for possible recovery. Contextualisation is an essential part of missiology, in calibrating appropriate mission to the distinctives of a particular nation or locality. Wales is shown to be a distinctive context for mission, both nationally and regionally, in relation to specific aspects: religious, geographic, ethnic, linguistic, cultural, social and political. Contextual studies have been done for other mission contexts, but not for Wales. This research seeks to address this lack. The thesis first outlines the development of the main approaches in global mission, their underlying assumptions, and their outworking in the mission of local churches in the West. The approaches have been identified as Evangelistic, Lausanne, Missio Dei, Liberal and Emergent. Drawing on hundreds of questionnaire responses and extensive interviews with Nonconformist leaders, the research examines how the different approaches to mission have been expressed in Wales, and how each approach adjusted to each aspect of context. The growth trends of the different approaches, patterns of church and mission, and adjustments to Welsh contexts in the first decade of the twenty-first century, or not, are then examined. The resulting analysis enables good practice to be identified, and approaches for effective mission suggested for the coming decades
“Why Can’t I Play?”: Transdisciplinary Learnings for Children with Disability’s Sport Participation
This article explores the constraints to mainstream sports participation of children with disability in community sports clubs and schools through their lived experiences and the perceptions of parents, teachers, coaches, and club officials. It does so by administering an open-ended survey instrument to a sample of participants recruited from schools, sporting facilities, and disability organizations in New South Wales and Victoria, Australia. The data were analysed through a transdisciplinary conceptual framework which brought together the social model of disability (disability studies) with the leisure constraints framework (leisure studies), which have been encouraged by both academics and practitioners. The findings identified ableist and disablist practices, creating an enabled understanding of the facilitators for social inclusion. Participants perceived that interrelated intrapersonal, interpersonal, and structural constraints excluded children from their desired sporting activities. Through applying the social model of disability to the leisure constraints framework, the findings and discussion showed that a great deal of what had been considered intrapersonal constraints of the child with disability could be reinterpreted as interpersonal and structural constraints through enabling socially inclusive practices. The implications are that a social model of disability brings a new social lens to understanding constraints to sport participation for children with disability and can produce effective strategies for inclusion in sport at schools and community sport clubs.</jats:p
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Assessment of the response of pollinator abundance to environmental pressures using structured expert elicitation
Policy-makers often need to rely on experts with disparate fields of expertise when making policy choices in complex, multi-faceted, dynamic environments such as those dealing with ecosystem services. For policy-makers wishing to make evidence-based decisions which will best support pollinator abundance and pollination services, one of the problems faced is how to access the information and evidence they need, and how to combine it to formulate and evaluate candidate policies. This is even more complex when multiple factors provide influence in combination. The pressures affecting the survival and pollination capabilities of honey bees (Apis mellifera), wild bees, and other pollinators are well documented, but incomplete. In order to estimate the potential effectiveness of various candidate policy choices, there is an urgent need to quantify the effect of various combinations of factors on the pollination ecosystem service. Using high-quality experimental evidence is the most robust approach, but key aspects of the system may not be amenable to experimentation or may be prohibitive based on cost, time and effort. In such cases, it is possible to obtain the required evidence by using structured expert elicitation, a method for quantitatively characterizing the state of knowledge about an uncertain quantity. Here we report and discuss the outputs of the novel use of a structured expert elicitation, designed to quantify the probability of good pollinator abundance given a variety of weather, disease, and habitat scenarios
How can an understanding of plant-pollinator interactions contribute to global food security?
Pollination of crops by animals is an essential part of global food production, but evidence suggests that wild pollinator populations may be declining while a number of problems are besetting managed honey bee colonies. Animal-pollinated crops grown today, bred in an environment where pollination was less likely to limit fruit set, are often suboptimal in attracting and sustaining their pollinator populations. Research into plant-pollinator interactions is often conducted in a curiosity-driven, ecological framework, but may inform breeding and biotechnological approaches to enhance pollinator attraction and crop yield. In this article we review key topics in current plant-pollinator research that have potential roles in future crop breeding for enhanced global food security
Bird pollination of Canary Island endemic plants
The Canary Islands are home to a guild of endemic, threatened bird pollinated plants. Previous work has suggested that these plants evolved floral traits as adaptations to pollination by flower specialist sunbirds, but subsequently they appear to be have co-opted passerine birds as sub-optimal pollinators. To test this idea we carried out a quantitative study of the pollination biology of three of the bird pollinated plants, Canarina canariensis (Campanulaceae), Isoplexis canariensis (Veronicaceae) and Lotus berthelotii (Fabaceae), on the island of Tenerife. Using colour vision models, we predicted the detectability of flowers to bird and bee pollinators. We measured pollinator visitation rates, nectar standing crops, as well as seed set and pollen removal and deposition. These data showed that the plants are effectively pollinated by non-flower specialist passerine birds that only occasionally visit flowers. The large nectar standing crops and extended flower longevities (>10days) of Canarina and Isoplexis suggests that they have evolved bird pollination system that effectively exploits these low frequency non-specialist pollen vectors and is in no way suboptimal. Seed set in two of the three species was high, and was significantly reduced or zero in flowers where pollinator access was restricted. In L. berthelotii, however, no fruit set was observed, probably because the plants were self incompatible horticultural clones of a single genet. We also show that, while all three species are easily detectable for birds, the orange Canarina and the red Lotus (but less so the yellow-orange Isoplexis) should be difficult to detect for insect pollinators without specialised red receptors, such as bumblebees. Contrary to expectations if we accept that the flowers are primarily adapted to sunbird pollination, the chiffchaff (Phylloscopus canariensis) was an effective pollinator of these species
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