Orientador: Marlies Sazima / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-10T19:00:29Z (GMT). No. of bitstreams: 1 Fracasso_CarlaMagioni_D.pdf: 3322816 bytes, checksum: 1ea062a574a452d00e5822ab7f58976b (MD5) Previous issue date: 2008 / Resumo: Esse trabalho traz informações sobre a fenodinâmica reprodutiva, as relações entre polinizadores e flores e o sistema reprodutivo em espécies de Melastomataceae ocorrentes no Parque Nacional da Serra da Canastra, em Minas Gerais. A sazonalidade expõe as plantas a mudanças periódicas na qualidade e abundância de recursos. Havia espécies em flor ao longo do ano com extensa sobreposição de floradas, porém o pico de intensidade dessa fenofase concentrou-se em curtos períodos. Não houve correlações significativas entre os fatores climáticos e essa fenofase, indicando que a floração dessas espécies provavelmente seja restringida por características filogenéticas do grupo. estames dos dois verticilos não têm distinção funcional e a disposição do androceu confere à flor simetria radial ou zigomorfa. De maneira geral, os polinizadores possuem tamanho corporal suficiente para agarrar o conjunto de elementos reprodutivos e, ao mesmo tempo, contatar o estigma antes da coleta de pólen. Todas as espécies são homogâmicas, contudo o pólen é liberado gradualmente durante a antese e o estigma, receptivo por longo período, pode receber pólen exógeno em mais de uma visita, aumentando potencialmente a quantidade de grãos aderidos às papilas estigmáticas, e conseqüentemente de óvulos fertilizados. Mudanças de cor foram resultantes da senescência floral e não induzidas pela polinização. Não houve frutificação por autopolinização espontânea, nem por agamospermia. As espécies são auto-compatíveis em variados graus, exceto Microlicia viminalis, cujos dados são insuficientes para determinar seu sistema reprodutivo. Tanto em flores manipuladas quanto sob condições naturais ocorreu alta taxa de sementes viáveis. As abelhas visitantes apresentaram comportamento de forrageio e adequação morfológica às flores de Melastomataceae, com exceção de Trigona sp. que não vibra e corta as anteras pilhando o pólen. As abelhas maiores são polinizadoras de flores de todos os tamanhos, ao contrário das abelhas menores que atuam polinizando flores pequenas, mas pilham flores maiores. Em uma segunda visita à mesma flor, todas as abelhas foram responsáveis pelo aumento na formação de frutos e principalmente, no número de sementes. A eficiência específica como polinizador de cada abelha, bem como sua freqüência são fatores indispensáveis para que seja possível determinar a contribuição real de cada visitante, bem como para caracterizar sua atuação como polinizador ou pilhador. Em Macairea radula ocorrem três formas florais, duas delas com reciprocidade nas alturas de um dos verticilos de estames e estilete. A terceira forma floral apresenta características intermediárias aos outros dois morfos. A hercogamia é considerada o principal modo de promover a polinização cruzada e, até o presente estudo, não havia relatos de heteromorfismo floral em Melastomataceae. Os morfos ocorrem em proporções semelhantes e a freqüência de visitas das abelhas entre eles é similar. A deposição diferenciada de pólen no corpo dos polinizadores aumentaria a chance de transferência eficiente inter-morfos, resultando em polinização cruzada / Abstract: This study examines the reproductive phenology, pollination ecology, and mating systems of 10 species of Melastomataceae that occur in the Serra da Canastra National Park, Minas Gerais. Seasonality exposes plants to periodic changes in quality and abundance of resources. Flowers of many species can be found throughout the year, but there are well-defined peaks of abundance. There are species with extensive flowering periods throughout the year, but the peaks are short. There are no significant correlations between climatic factors and phenology, which suggests that flowering, may be constrained by phylogeny. Stamens in the two whorls lack a functional distinction, and their arrangement confers radial or zygomorphic symmetry to the flowers. Generally, pollinators are large enough to grasp the stamens and stigma simultaneously before vibrating to collect pollen. Anther dehiscence and stigma receptivity are synchronous, but pollen is released gradually and stigmas remain receptive for an extended period, thereby increasing pollination and fruit-set. Flower color changes with age (senescence) and is not hastened by pollination. There was no production of fruit either by self-pollination or agamospermy. Except for Microlicia viminalis (for which data are insufficient to determine its mating system), all species are self-compatible. High values of viable seeds were obtained from both hand-pollinated flowers and those pollinated under natural conditions. The visiting bees showed morphological and behavioral adaptations to pollinate the flowers of Melastomataceae, except Trigona sp., which did not vibrate, but rather pierced anthers to steal pollen. In general, larger bees are pollinators of large and small flowers, whereas smaller bees pollinate small flowers but rob large flowers of pollen. For all bee species, second visits to the same flower increased fruit-set and seed number. To determine the actual effectiveness of each visitor, it is necessary to measure its efficiency and frequency, as well as its behavior as a pollinator or pollen robber. Three flower morphs occur in Macairea radula, two of which show reciprocal heights of one of the stamen whorls and style. The third morph displays intermediate characteristics. This is the first report of floral heteromorphism in Melastomataceae. The morphs occur in similar frequencies and bees visit them at similar rates. Differential pollen deposition on the bodies of pollinators promotes pollen transfer between morphs, resulting in cross-pollination / Doutorado / Doutor em Biologia Vegetal

Pedicularis sceptrum-carolinum is threatened in much of its geographic range. As it reproduces vegetatively only to a limited extent, the species relies heavily on pollinators for reproduction. One aspect often overlooked in restoration efforts is the pollination ecology of flowering plants and their pollinators. To get a better understanding of the pollination ecology of P. sceptrum-carolinum in northern Sweden, their flower visitors were identified, and the number of flower visits was counted for flowering individuals at three different sites. The nearby flowering plant community was inventoried around each investigated P. sceptrum-carolinum. It was tested whether the number of flower visits were similar among sites, between large and small populations, and between populations with a majority of fresh flowers and populations with a majority of senescent flowers. To investigate whether the nearby plant community is important for the pollination of the species, the correlation between flower visits of P. sceptrum-carolinum and nearby flower abundance and diversity was analysed. No difference was found between sites, between large and small populations, or between populations where the majority of flowers were fresh and populations with a majority of flowers which had senesced. A moderate positive correlation was found between number of flower visits and nearby flower abundance and diversity respectively, if one site with an exceptionally large abundance of Trifolium pratense was excluded. As abundance and diversity of the nearby flowering plants were themselves highly correlated, their individual effect on flower visits of the studied P. sceptrum-carolinum could not be told apart in this study.

Among terrestrial orchids, and particularly among the subtribe Orchidinae, flies are underrepresented as pollinators. The European Neotinea ustulata, which developed specialized pollination by tachinid flies, is known to produce high relative concentrations of the floral cuticular alkenes (Z)-11-tricosene and (Z)-11-pentacosene (referred to as (Z)-11-C23/C25enes), which seem to be uncommon among orchid flowers. If the evolution of tachinid pollination is related to that of (Z)-11-C23/C25enes, we can expect that closely related species have a different floral chemical pattern and significantly small or no production of (Z)-11-C23/C25enes, independently of their pollinator guild identity (e.g., bees, flies, moths). We chemically compared the floral cuticular composition among Neotinea species, performed electrophysiological analyses, reconstructed the phylogenetic Orchidinae tree, and identified the evolutionary history of pollinator guild and (Z)-11-C23/C25enes production within the Orchidinae. Neotinea ustulata has evolved a markedly different floral cuticular composition compared to other Neotinea and produces both compounds ((Z)-11-C23/C25enes) in high relative quantities (i.e., above 8% in combination), which are detectable by tachinid antennae. Moreover, most Orchidinae taxa have minimal or no production of these alkenes, independently of the identity of their pollinator guild. Our ancestral reconstruction suggested that (Z)-11-C23/C25enes production was an evolutionary exaptation in Neotinea, whereas tachinid pollination was a unique evolutionary innovation for N. ustulata. Floral cuticular composition and, in particular, the combined production of (Z)-11-C23/C25enes at relatively high concentrations is intimately linked to the evolution of tachinid pollination within the Orchidinae.

Difficulties in pollen transfer have adversely affected seed production of hybrid onion (Allium cepa L.) in the United States. Six onion cultivars were examined for differential attractiveness to the honey bee (Apis mellifera L.). Honey bees clearly discriminated between the onion cultivars in both open plots and caged plots. Nectar secretion, nectar sugar concentration, nectar sugar composition, mectar potassium content, and flower phenology were correlated with honey bee visitation. Nectar secretion rates ranged from 0.54 to 0.84 ul per floret per day. Onion cultivars also demonstrated differential flowering potential. The cultivars produced from 176 to 359 flowers per umbel with 32 to 74 umbels per 30 onions. All onion cultivars examinaed contained viscous nectar with sugar concentrations ranging from 51 to 65% of total dissolved solids. Onion nectar was analyzed by gas chromatography to determine qualitative sugar differences among onion cultivars. All cultivars were hexose dominant with an approximately 1:1 fructose:glucose ratio. However, fructose was slightly more abundant than glucose. Sucrose was much less abundant than the hexose sugars. Atomic absorption spectrophotometry revealed little difference in potassium content among the A. cepa cultivars. Nectar potassium levels ranged from 5,300 ppm to 6,900 ppm. Cultivars with higher nectar potassium levels had fewer honey bee visits. Two honey bee bioassays were conducted. The first bioassay simulated the sugar and potassium composition of each onion cultivar. The honey bees selectively foraged on simulated nectars with low potassium and high sugar concentrations. The second bioassay was designed to test honey bee response to "phenolic-rich" solutions. The natural compounds tested were dilutions of salt cedar (Tamarix pentandra Pall.) honey, almond (Prunus dulcis Mill.) honey, and aloe (Aloe littoralis L.) nectar. The pure synthetic compounds tested were caffeic acid and genestic acid. Generally, honey bees foraged preferentially on the lower phenolic concentrations, indicating that compounds high in phenolic composition inhibit honey bee foraging. Finally, seed yields of each of the cultivars were compared. Wide variations in yields were correlated with honey bee visitation, sugar composition, potassium levels, and flower phenology.

No description available.

In contrast to the wealth of knowledge concerning sucrose-rewarded learning mechanisms, the question of what bees learn when they collect pollen from flowers has been little addressed. Pollen-rewarded learning is of interest not only in furthering our understanding of associative conditioning pathways in the insect brain, it may also shed light on the role that cognitive processes may have played in shaping the early evolutionary relationship between plants and their pollinators, given that pollen is thought to have been the ancestral reward for flower visitors. Thus the central aim of this thesis was to demonstrate the conditions under which pollen may reinforce learning of floral features in two model species, the honeybee (Apis mellifera) and bumblebee (Bombus terrestris). Having developed a number of paradigms for the study of pollen-rewarded learning, here I ask what bees might learn during pollen collection, both in terms of the sensory characteristics of pollen itself and additional cues paired with this reward. Freely flying bees were shown to be sensitive to differences in the type of pollen offered for collection and were able to associate the presence of a coloured stimulus with both the availability and quality of the pollen reward. The sensory pathways involved in the evaluation of pollen were also investigated. When bees were restrained, in order to more tightly control exposure to the reward, pollen was not found to support learning in an olfactory conditioning task. Furthermore, when delivered in solution with sucrose, pollen was found to inhibit learning relative to bees rewarded with sucrose alone. It seems that pollen contains compounds which are perceived as distasteful by bees and that through the contamination of nectar, pollen may influence bees foraging decisions via differential learning and recognition of floral cues.

Insect pollination is a vital ecosystem service, essential for both wild and domesticated plants, yet to-date there are no standardised national schemes to monitor its status. Thus this PhD focused on assessment of pollination provision in UK urban green spaces, using a combination of citizen science and field/laboratory methods. Each of the following thesis chapters considers a specific pollination-related theme: The need for pollination. Demonstrating how much gardeners need insect pollination is important to underpin public support for pollinator conservation. During 2014-2015, online questionnaires were used to collect information about the crops grown in domestic green spaces and gardening practices used. Participants highly valued ‘growing their own', and three of five crops grown by the majority (tomatoes, apples, strawberries) have high requirements for insect pollination. A ‘garden shop calculator' spreadsheet was also tested (positively) as a quick way to calculate the equivalent bought-value of garden crops and the proportion directly attributable to insect actions. Assessment of pollination provision. Citizen science volunteers undertook a simple direct pollination experiment (exclusion, hand pollination, local), requiring treatment randomisation and accurate yield recording. The main ‘Bees ‘n Beans' projects used Vicia faba to monitor bumblebee pollination, detecting no national deficit during 2014-2016. This suggests that the domestic pollination needs of V. faba are currently met, and that urban populations of long-tongued bumblebees are sufficient to provide it. The potential of using other plants to cover wider pollinator populations was also explored, identifying Allium hollandicum as suitable. The effects of companion planting. Using tomato plants to examine whether co-planting crops with flowering plants boosts pollination provision (‘magnet species' effects), or distracts insects. Provided plants were hosted in volunteered gardens and school grounds in Brighton in 2015 & 2016. No effect (improved or detrimental) of co-flowering plants was found on tomato yields at either site type. Using citizen science to monitor pollination services. This chapter combined findings from other chapters and a final questionnaire, which focused on participants' motivations and willingness to make behavioural changes after taking part. It concludes that the projects have demonstrated volunteers' ability and willingness to follow experimental protocols under guidance, to collect meaningful data at otherwise-impractical geographical scales. Suggested protocol. This details the finalised Bees ‘n Beans approach and how it relates to other potential pollination monitoring methods. I propose that this style of project is suitable for incorporation into national monitoring scheme development.

No description available.

Thesis (Ph.D.) - Simon Fraser University, 2005. / Theses ( Dept. of Biological Sciences) / Simon Fraser University. Includes bibliographical references. Also issued in digital format and available on the World Wide Web.

Thesis (M. Sc.)--York University, 2001. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 89-94). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ67744.