1000 resultados para pollination efficiency


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Main conclusion Switches between pollination syndromes have happened frequently during angiosperm evolution. Using QTL mapping and reciprocal introgressions, we show that changes in reproductive organ morphology have a simple genetic basis. In animal-pollinated plants, flowers have evolved to optimize pollination efficiency by different pollinator guilds and hence reproductive success. The two Petunia species, P. axillaris and P. exserta, display pollination syndromes adapted to moth or hummingbird pollination. For the floral traits color and scent, genetic loci of large phenotypic effect have been well documented. However, such large-effect loci may be typical for shifts in simple biochemical traits, whereas the evolution of morphological traits may involve multiple mutations of small phenotypic effect. Here, we performed a quantitative trait locus (QTL) analysis of floral morphology, followed by an in-depth study of pistil and stamen morphology and the introgression of individual QTL into reciprocal parental backgrounds. Two QTLs, on chromosomes II and V, are sufficient to explain the interspecific difference in pistil and stamen length. Since most of the difference in organ length is caused by differences in cell number, genes underlying these QTLs are likely to be involved in cell cycle regulation. Interestingly, conservation of the locus on chromosome II in a different P. axillaris subspecies suggests that the evolution of organ elongation was initiated on chromosome II in adaptation to different pollinators. We recently showed that QTLs for pistil and stamen length on chromosome II are tightly linked to QTLs for petal color and volatile emission. Linkage of multiple traits will enable major phenotypic change within a few generations in hybridizing populations. Thus, the genomic architecture of pollination syndromes in Petunia allows for rapid responses to changing pollinator availability.

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蚂蚁和被子植物之间存在广泛、普遍和多样的关系,但蚂蚁为被子植物传粉的报道却很少。本文通过对分布于四川省黄龙寺自然保护区黄龙沟内鸟巢兰属和对叶兰属的三种花结构十分相似的植物(高山鸟巢兰Neottia listeroides、小叶对叶兰Listera smithii以及花叶对叶兰L. puberula var. maculata)的传粉生态学研究,首次在国内报道高山鸟巢兰和花叶对叶兰中蚂蚁参与的传粉现象,并探讨了蚂蚁参与的传粉系统中蚂蚁传粉的特点、传粉效率、蚂蚁活动特点与防止自花授粉的关系、以及蚂蚁传粉的作用等问题。同时通过蚂蚁参与传粉的高山鸟巢兰和花叶对叶兰以及没有蚂蚁参与传粉的小叶对叶兰的生境对比,初步分析了蚂蚁参与传粉的生境条件。 黄龙沟内小叶对叶兰、高山鸟巢兰和花叶对叶兰居群水平的花期分别可持续27 d、40 d和50 d,大量开花期(~60%)分别在6月下旬到7月上旬、7月中下旬和8月。这3种植物都具暴露的花蜜,花蜜位于唇瓣中央不明显蜜槽内,花蜜量很小。访问小叶对叶兰的昆虫非常少,2005年和2007年均没有观察到传粉者。在2005年,姬蜂和瘿蜂为花叶对叶兰主要传粉者。在2007年,蚂蚁(包括细胸蚁和立毛蚁)分别是高山鸟巢兰和花叶对叶兰最主要的传粉者,其单花访问次数、携粉次数以及授粉次数分别在这2种植物的所有访问昆虫中是最高的。蚂蚁沿唇瓣蜜槽取食花蜜,到达唇瓣基部后,在高山鸟巢兰上,一般情况下蚂蚁头部不能接触到蕊喙先端,只有当蚂蚁头部向上抬起,才能触碰到蕊喙,花粉团通过蕊喙先端释放的粘滴粘在蚂蚁头部最顶端;而在花叶对叶兰上,只要蚂蚁在唇瓣基部活动就可以触碰到蕊喙,花粉团粘在蚂蚁头部的前额处。当小叶对叶兰、高山鸟巢兰和花叶对叶兰的蕊喙先端被触碰后,立即向下运动盖住柱头,分别约9 h、21 h和23 h重新抬起至药帽位置。蕊喙的这种运动可以避免因蚂蚁的重复访问而引起自花授粉的发生。繁育系统实验表明,这3种植物是自交亲和的,但必须依靠昆虫进行传粉。自然条件下,小叶对叶兰的自然结实率在2005和2007年分别为18.03%和14.42%,花叶对叶兰在2005和2007年分别为17.05%和43.20%,高山鸟巢兰在2007年为19.77%。 细胸蚁和立毛蚁在高山鸟巢兰和花叶对叶兰上的访问频率差异不大,前者略低于后者,但高山鸟巢兰的结实率却远低于花叶对叶兰。这主要是由于高山鸟巢兰与细胸蚁和立毛蚁之间形态上的不完全适应,而花叶对叶兰与2种蚂蚁之间形态上却较为适应的缘故。虽然2007年2种蚂蚁是高山鸟巢兰和花叶对叶兰最有效的传粉者,但这种传粉关系可能只是在特定时间和独特生态环境中出现的。生境干旱可能是导致蚂蚁访花和传粉的重要因素。我们的研究结果也初步表明当环境变化导致原有的主要传粉者缺失时,蚂蚁可以起到补充传粉的作用。

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Em áreas experimentais das Fazendas de Ensino e Pesquisa da UNESP/Campus de Ilha Solteira e Jaboticabal foram selecionadas e marcadas 20 plantas hermafroditas e 20 femininas dos cultivares Sunrise Solo, Improved Sunrise Solo cv.72/12 e Baixinho de Santa Amália. As sementes provenientes dos frutos selecionados foram plantadas para analisar-se a eficiência da autofecundação e a freqüência dos sexos nas progênies. Posteriormente, amostras de tecido foliar jovem das plantas matrizes foram coletadas para a extração de DNA. Foram construídas cinco bibliotecas enriquecidas de seqüências microsatélites, utilizando-se as sondas (TCA)10, (TC)13, (GATA)4, (CAC)10 e (TGAG)8. Foi possível o desenvolvimento de primers somente com a biblioteca que utilizou a sonda (TCA)10 . Esta permitiu o desenho de 32 pares de primers. Destes, 31 apresentaram padrão de banda única em agarose Metaphor e em acrilamida. Para o primer S36 foram observadas 2 bandas, mas sem polimorfismo para diferenciação da forma sexual na cultura do mamoeiro. No entanto, estes primers poderão ser testados na investigação de outras características em populações segregantes desta espécie e de espécies afins, análises de germoplasma, identificação de cultivares, evolução parental e marcas em melhoramento assistido.

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The role of mutualisms in contributing to species invasions is rarely considered, inhibiting effective risk analysis and management options. Potential ecological consequences of invasion of non-native pollinators include increased pollination and seed set of invasive plants, with subsequent impacts on population growth rates and rates of spread. We outline a quantitative approach for evaluating the impact of a proposed introduction of an invasive pollinator on existing weed population dynamics and demonstrate the use of this approach on a relatively data-rich case study: the impacts on Cytisus scoparius (Scotch broom) from proposed introduction of Bombus terrestris. Three models have been used to assess population growth (matrix model), spread speed (integrodifference equation), and equilibrium occupancy (lattice model) for C. scoparius. We use available demographic data for an Australian population to parameterize two of these models. Increased seed set due to more efficient pollination resulted in a higher population growth rate in the density-independent matrix model, whereas simulations of enhanced pollination scenarios had a negligible effect on equilibrium weed occupancy in the lattice model. This is attributed to strong microsite limitation of recruitment in invasive C. scoparius populations observed in Australia and incorporated in the lattice model. A lack of information regarding secondary ant dispersal of C. scoparius prevents us from parameterizing the integrodifference equation model for Australia, but studies of invasive populations in California suggest that spread speed will also increase with higher seed set. For microsite-limited C. scoparius populations, increased seed set has minimal effects on equilibrium site occupancy. However, for density-independent rapidly invading populations, increased seed set is likely to lead to higher growth rates and spread speeds. The impacts of introduced pollinators on native flora and fauna and the potential for promoting range expansion in pollinator-limited 'sleeper weeds' also remain substantial risks.

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Natural selection mediated by pollinators has influenced the evolution of floral diversity of the flowering plants (angiosperms). The scope of this thesis was to study: 1) phenotypic selection, 2) mating systems, and 3) floral shifts involved in plant speciation. Model plant species were Platanthera bifolia and P. chlorantha (Orchidaceae). These orchids are moth-pollinated, strictly co-sexual (bisexual flowers), and produce a spike that displays 10-20 white flowers. I explored the influence of characters on plant fitness by using multiple linear regressions. Pollen removal (male fitness) and fruit set (female fitness) increased with more flowers per plant in three P. bifolia populations. There was selection towards longer spurs in a dry year when average spur length was shorter than in normal-wet years. Female function was sensitive to drought, which enabled an application of the male function hypothesis of floral evolution (Bateman's principle). The results show that selection may vary between populations, years, and sex-functions. I examined inbreeding by estimating levels of geitonogamy (self-pollination between flowers of an individual) with an emasculation method in two P. bifolia populations. Geitonogamy did not vary with inflorescence size. Levels of geitonogamy was 20-40% in the smaller, but non-significant in the larger population. This may relate to lower number of possible mates and pollinator activity in the smaller population. Platanthera bifolia exhibits the ancestral character state of tongue-attachment of pollinia on the pollinator. Its close relative P. chlorantha attaches its pollinia onto the pollinator's eyes. To explore the mechanism of a floral shift, pollination efficiency and speed was compared between the two species. The results showed no differences in pollination efficiency, but P. chlorantha had faster pollen export and import. Efficiency of pollination in terms of speed may cause floral shifts, and thus speciation.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This research focuses on reproductive biology and pollination ecology of entomophilous angiosperms, with particular concern to reproductive success in small and isolated populations of species that occur at their distribution limits or are endemic. I considered three perennial herbs as model species: Primula apennina Widmer, Dictamnus albus L. and Convolvulus lineatus L. I carried out field work on natural populations and performed laboratory analyses on specific critical aspects (resource allocation, pollen viability, stigmatic receptivity, physiological self-incompatibility, seed viability), through which I analysed different aspects related to plant fitness, such as production of viable seed, demographic structure of populations, type and efficiency of plant-pollinator system, and limiting factors.

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The aim of this study was to determine the collection efficiency of ultrafine particles into an impinger fitted with a fritted nozzle tip as a means to increase contact surface area between the aerosol and the liquid. The influence of liquid sampling volume, frit porosity and the nature of the sampling liquid was explored and it was shown that all impact on the collection efficiency of particles smaller than 220 nm. Obtained values for overall collection efficiency were substantially higher (~30–95%) than have been previously reported, mainly due to the high deposition of particles in the fritted nozzle tip, especially in case of finer porosity frits and smaller particles. Values for the capture efficiency of the solvent alone ranged from 20 to 45%, depending on the type and the volume of solvent. Additionally, our results show that airstream dispersion into bubbles improves particle trapping by the liquid and that there is a difference in collection efficiencies based on the nature and volume of the solvent used.

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The main objective was to compare the environmental impacts of a building undergoing refurbishment both before and after the refurbishment and to assist in the design of the refurbishment with what is learned.

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This paper describes the process adopted in developing an integrated decision support framework for planning of office building refurbishment projects, with specific emphasize on optimising rentable floor space, structural strengthening, residual life and sustainability. Expert opinion on the issues to be considered in a tool is being captured through the DELPHI process, which is currently ongoing. The methodology for development of the integrated tool will be validated through decisions taken during a case study project: refurbishment of CH1 building of Melbourne City Council, which will be followed through to completion by the research team. Current status of the CH1 planning will be presented in the context of the research project.

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This paper will summarise the findings from a study that explored the link between dwelling design, or type, and energy efficiencies in sub-tropical climates. An increasing number of government and private sector development companies are initiating projects that aim to deliver enhanced environmental outcomes at both sub-divisional and dwelling levels. The study used AccuRate, a new thermal modelling tool developed by CSIRO that responds to the need to improve ventilation modelling. The study found that dwellings developed in conjunction with the Departments of Housing and Public Works have set the benchmark. It provides a snapshot of the energy efficiency of a range of dwelling types found in recent subdivisions. However, the trend toward increasing urban densities may reduce the likelihood that cooling breezes will be available to cool dwellings. The findings are relevant to regulators, designers and industry in all states interested in reducing the energy used to cool dwellings in summer.

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The ability to assess a commercial building for its impact on the environment at the earliest stage of design is a goal which is achievable by integrating several approaches into a single procedure directly from the 3D CAD representation. Such an approach enables building design professionals to make informed decisions on the environmental impact of building and its alternatives during the design development stage instead of at the post-design stage where options become limited. The indicators of interest are those which relate to consumption of resources and energy, contributions to pollution of air, water and soil, and impacts on the health and wellbeing of people in the built environment as a result of constructing and operating buildings. 3D object-oriented CAD files contain a wealth of building information which can be interrogated for details required for analysis of the performance of a design. The quantities of all components in the building can be automatically obtained from the 3D CAD objects and their constituent materials identified to calculate a complete list of the amounts of all building products such as concrete, steel, timber, plastic etc. When this information is combined with a life cycle inventory database, key internationally recognised environmental indicators can be estimated. Such a fully integrated tool known as LCADesign has been created for automated ecoefficiency assessment of commercial buildings direct from 3D CAD. This paper outlines the key features of LCADesign and its application to environmental assessment of commercial buildings.