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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Success of micropropagated woody landscape plants under northern growing conditions and changing environment

Pihlajaniemi, H. (Henna) 01 December 2009 (has links)
Abstract Plant registration and selection work aimed at identifying the best genotypes for northern landscaping has been carried out in Finland since the 1980’s. In the University of Oulu Botanical Gardens, micropropagation methods have been developed for several woody plant taxa registered during the POHKAS (Northern Hardy Plants) project. Micropropagation is an effective method to conserve valuable genetic characteristics and to produce plantlets from woody species with limited mother stock material and in a limited time period. In this study the long-term field phenology and success of 19 micropropagated shrub and tree taxa was followed in plant selection experiments. Experiments were conducted at four northern field sites presenting different climatic conditions. Of the phenological monitoring parameters, the onset of foliation and flowering in the field revealed a strong relation to spring time temperature, being obviously latest to occur in northernmost site. The gradient between southern and northern sites for autumn phenology was not so obvious. However, between the different genotypes, the greatest differences were observed in the timing of autumn colouration and defoliation. Winter hardiness also showed clear differences between genotypes. Of the success parameters, it was most decisive as winter hardy genotypes had a higher occurrence of flowers and ornamental appearance, for example in Rosa majalis ‘Tornedal’. Some of these hardy genotypes with known characteristics were introduced to northern tourism areas to create examples of sustainable landscaping. Further, a list of potential plants for different northern sites was compiled. Special forms with both scientific and ornamental value are occasionally found in wild species. One example of this is the red-leaved form of a pubescent birch, Betula pubescens f. rubra, which was studied in the plant selection experiments, and was used as a model tree to evaluate the role of anthocyanins in northern plants in a case study of northern birches. In the case study, the red-leaved pubescent birch showed some differences in flavonoid responses and growth rate in comparison to Betula pubescens and Betula pubescens ssp. czerepanovii. Phenology of the B. p. f. rubra was corresponding to that of the B. pubescens. For cultivated woody plants the most important selection criteria for the northern areas are the suitability to local climate i.e. timing of phenological events and winter hardiness. Foliar anthocyanins seem to increase adaptation to northern growing conditions with high light intensity and low temperature.
272

An analysis of spring bird migration phenology in Kansas

Patterson, Judd January 1900 (has links)
Master of Arts / Department of Geography / John A. Harrington Jr / In late summer and fall, many migratory birds journey south from the North American Great Plains to spend the winter in locations with greater food availability. As spring returns, a combination of genetics and environmental cues trigger these birds to return north to their breeding grounds. Several bird migration phenology studies from Europe, Australia, and the eastern/northern United States have discovered that some bird species are returning earlier in the spring, a change that has often been correlated with a warming climate. This study aimed to be the first to analyze possible changes in both spring bird migration phenology and regional spring climate change in Kansas. First arrival dates (FADs) were collected for thirty bird species, resulting in a database with over 6,000 FAD entries. For northeast Kansas, 1997-2007 median arrival dates were calculated and compared to dates published by Dr. Richard Johnston in 1965. In southcentral Kansas, 1997-2007 and 1947-1967 median arrival dates were calculated and compared. Temperature data from spring (February through May) were also obtained from the National Climate Data Center's United States Historical Climatology Network for all stations within northeast and south central Kansas and temporal trends were analyzed with linear regression analysis. A comparison between median arrival dates in northeast Kansas found that eleven species had altered their arrival date by a potentially significant number of days. Nine of these had advanced their arrival and two showed a delay. In south central Kansas, nine species were shown to have statistically significant differences in median arrival dates between time periods. Six of these showed an advance and three showed a delay. Five species showed the same trend between both regions, with four arriving earlier by an average 9.4 days and one delaying by an average of 4.5 days. Temperature trends for both subregions in Kansas showed significant warming of 1.8-2.6°F (1.0-1.4°C) over the last century, with the largest warming observed in February and associated strongly with increasing minimum temperatures. The results from this study provide the first evidence that some bird species have recently altered the timing of their arrival in Kansas, with a greater shift toward earlier arrival dates. While the majority of these shifts were correlated with spring warming in Kansas, additional research is necessary to determine the precise cause(s) of these phenological shifts. Still, given existing literature and Intergovernmental Panel on Climate Change predictions for continued warming in the next century, continued alterations to bird migration phenology seem likely.
273

Does the Matrix Matter? A Comparison on Phenology and Habitat utilization of Two Treefrog Species in the Big Cypress National Preserve

Isola, Monica 09 December 2011 (has links)
Habitat loss and fragmentation are some of the causes of biodiversity decline. Naturally fragmented landscapes serve as analogues to anthropogenically fragmented landscapes. Recent studies have shown that the matrix between patches has an important role in the dynamics of patch-dwelling species. I studied phenology and habitat utilization of Hyla cinerea and Hyla squirella, the two most common yet understudied frogs, in two patchy landscapes of the Big Cypress National Preserve. Frogs were sampled in five domes and in their adjacent matrix, monthly, between 2006 and 2008. Using nighttime visual encounter surveys, specimens encountered were identified to species, and perch type, perch height and capture location were recorded. Analysis showed differences in abundance and habitat use patterns between patches and matrices for the two species across the two landscapes. These differences indicate that the matrix is important in shaping patterns of abundance and habitat use in fragmented landscapes.
274

Long-term Habitat Trends in Barren-ground Caribou

White, Lori January 2013 (has links)
Global and local climate patterns may affect barren-ground caribou (Rangifer tarandus groenlandicus) populations. I predicted global climate changes to be correlated with periods of population decline, and local changes to be more pronounced on the habitat of caribou with a declining population. In chapter 1, the Arctic Oscillation (AO), changes in normalized difference vegetation index and phenology were used as measures of global and local climate. In chapter 2 environmental variables and caribou presence points were used to build Maxent habitat models. There was no consistent correlation with the positive AO phase and periods of population decline, or phenology trends and the habitat of caribou with a declining population. Maxent models underestimated the amount of suitable habitat spatially and failed to model suitable habitat temporally. This thesis is the first to look at a range of density-independent variables over a long time period and model suitable habitat for multiple herds.
275

Temporal Ecology of a Subalpine Ecosystem: Plant Communities, Plant-Pollinator Interactions, and Climate Change

CaraDonna, Paul James, CaraDonna, Paul James January 2016 (has links)
Ecological systems are inherently dynamic, and a primary way in which they are dynamic is through time. Individual organisms, populations, communities, species interactions, and ecosystem functions all follow a temporal progression from the past, to the present, and into the future. This temporal progression can occur over the course of minutes, hours, days, weeks, months, years, decades, or various other timescales. In this sense, temporal dynamics are an intrinsic property of all biological systems. In fact, one of the most prominent signals of recent global climate change is the significant change in the timing of biological events for a diversity of organisms. In light of this widespread pattern, there is a renewed interest in understanding the multifaceted importance of time in ecology. In this dissertation, I investigate the temporal ecology of a subalpine ecosystem, specifically focusing on flowering plant communities and plant-pollinator interactions. I examine the temporal dynamics of this system over multiple decades in response to ongoing climate change as well as over shorter time scales within a growing season. Using a 39-year record of flowering phenology, I show that species-specific shifts in the timing of flowering in response to climate change can substantially reshape a subalpine plant community over this time period. Community phylogenetic analyses reveal that these changes are largely independent of evolutionary history. Using a laboratory experiment, I show that the timing of an important harsh abiotic event-low temperatures that cause frost damage to plants-can differentially affect flowering plant species, with implications for plant demography, community structure, and interactions with pollinators. Finally, I show that plant-pollinator interactions exhibit substantial within-season temporal turnover, and that this temporal flexibility of plant-pollinator interactions from one week to the next is consistent and predictable across years. Taken together, this dissertation provides a multifaceted investigation of the temporal ecology of plant communities and plant-pollinator interactions, revealing the important consequences of ecological timing at short-term and longer-term scales.
276

Colonization and adaptations of Ficus in Taiwan / Colonisation et adaptations de figuiers à Taïwan

Bain, Anthony 16 December 2011 (has links)
L'ile de Taiwan est apparue, il y a deux millions d'années. Nous avons étudié les figuiers de Taiwan afin de comprendre comment l'ile fut colonisée et comment l'insularité a pu affecter les espèces colonisatrices. Le genre Ficus est caractérisé par son association mutualiste avec des insectes pollinisateurs extrêmement dispersifs. De plus les figues, inflorescences fermées des Ficus, sont consommés par un grand nombre d'espèces qui elles aussi dispersent efficacement les graines. Nous avons développé une série de marqueurs génétiques afin de pouvoir étudier plusieurs espèces avec les mêmes outils. Ensuite nous avons analysé la structure génétique dans Taiwan d'un groupe de quatre espèces. Une espèce présenta une différenciation génétique claire dans le Sud de Taiwan au climat plus chaud, suggérant la possibilité un début de spéciation écologique chez une espèce hautement dispersive. Une seconde espèce a montré des indices de processus de sélection en cours dans le Sud de Taiwan. A une échelle plus étendue, nous avons montre que les données microsatellites et spécifiquement les R statistiques donnent un premier aperçu de la phylogéographie des figuiers. Pour plusieurs espèces, l'Asie continentale semble être la trame de fond génétique de ces espèces malgré une forte différenciation parmi les populations. Pour Ficus variegata, nous avons montré que la colonisation de Taiwan a pour origine les Philippines et nous n'avons pas détecté de trace de flux génétique venant du continent. L'étude de la phénologie reproductive des Ficus suggère que seulement des espèces produisant de fréquentes récoltes ont colonisé l'ile. Ces travaux ouvrent de nombreuses perspectives sur la réponse des figuiers à l'insularité. / The Island of Taiwan appeared some two million years ago. We investigated the Ficus species of Taiwan in order to understand how the island was colonized and how insular conditions affected the colonizing species. Genus Ficus is characterized by its mutualistic association with highly dispersive pollinating wasps. Further figs, the closed inflorescences of Ficus, are consumed by a large number of highly efficient seed dispersers. We developed a set of portable genetic markers in order to analyze several species using a single set of markers. We then analyzed genetic structuring within Taiwan in a set of four species. One species presented clear genetic differentiation in the warm south Taiwan, suggesting the possibility of incipient ecological speciation in a highly dispersive species. Another species presented indications of ongoing selective processes also in south Taiwan. On a broader scale we show that microsatellite data and notably R statistics provide useful insights into Ficus phylogeography. In several species, continental Asia seems to correspond to a single genetic background despite strong genetic differentiation among populations. For Ficus variegata, we show that it colonized Taiwan from the Philippines and we detect no trace of gene flow from the continent. An investigation of Ficus reproductive phenology suggests that only species producing frequent fig crops have established on the island. This work opens up a series of perspectives on the response of Ficus to insular conditions.
277

Sorghum phenolic extracts : their storage stability and antioxidant activity in sunflower oil

Sikwese, Fred Edington 21 July 2008 (has links)
Whole grain and bran samples of two Malawian sorghums, Phatafuli, (a brown-coloured condensed tannin variety) and Shabalala, (a white-coloured condensed tannin-free variety) were analysed for their content of total phenols, condensed tannins and antioxidant activities. The effect of oxidizing conditions during extraction, and the storage stability of a freeze-dried crude phenolic extract (CPE) from the condensed tannin sorghum bran as influenced by packaging, storage temperature and length of storage, in relation to its content of total phenols, condensed tannins and antioxidant activity was also investigated. Antioxidant activity of the CPE, in comparison with tertiary butyl hydroquinone (TBHQ), was then evaluated in sunflower oil at concentrations of 1000, 1500 and 2000 ppm in the absence or presence of ferric ions at 2.2 and 4.4 ppm in the dark at 65oC.Progression of oxidation was monitored by measurement of peroxide values (PV) and anisidine values (AV) during a 14-day storage period. Phatafuli contained higher content of total phenols and antioxidant activity than Shabalala both in the whole grain and the bran, probably due to the presence of condensed tannins in Phatafuli sorghum, which were not detected in Shabalala sorghum. For both sorghum varieties, the bran contained higher levels of total phenols and antioxidant activity than the whole grain, confirming that phenolic compounds in sorghum are largely concentrated in the bran. Antioxidant activities of the sorghum varieties correlated highly with their total phenol and condensed tannin contents, suggesting that the phenolic compounds were largely responsible for the antioxidant activities of the sorghum grains. Bubbling of oxygen into the liquid crude phenolic extract did not have any significant effect on the parameters tested. Similarly, vacuum-packed samples did not differ significantly in the parameters tested from the samples that were not vacuum-packed. CPE samples stored at –20oC had significantly higher levels of total phenols, condensed tannins and antioxidant activity than those stored at 25oC during some days of storage. Storage time was however the major factor influencing the levels of total phenols, condensed tannins and antioxidant activity of the CPE from Phatafuli sorghum during storage, which suggested that CPE from condensed tannin sorghum bran might need to be used shortly after extraction to ensure optimum antioxidant activity. There was an insignificant correlation between the antioxidant activities of the CPE and their phenolic contents during storage, which could have been due to the formation of new compounds with a lower antioxidant capacity. The CPE inhibited oxidation of sunflower oil as shown by lower peroxide values and anisidine values compared to control samples. The CPE was however less effective in reducing peroxide values compared to TBHQ, but was similar to TBHQ in reducing anisidine values. In the presence of ferric ions, the CPE appeared to be less effective in reducing peroxide values compared to TBHQ, but appeared to be more effective than TBHQ in reducing anisidine values. The results showed that the tannin sorghum bran CPE appeared to act as both lipid radical scavengers and metal chelators. The CPE however imparted colour to the sunflower oil, which could limit its application as a natural antioxidant in edible oils. / Dissertation (MSc(Agric) Food Science and Technology)--University of Pretoria, 2008. / Food Science / unrestricted
278

Biologia floral, reprodutiva e cariótipos de espécies de Pseudobombax Dugand (Bombacoideae, Malvaceae) do sudeste do Brasil / Floral biology, reproductive and kariotypes of species Pseudobombax Dugand (Bombacoideae, Malvaceae) of southeastern Brazil

Nasario, João Paulo Sardin, 1990- 24 August 2018 (has links)
Orientador: Eliana Regina Forni Martins / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T09:37:20Z (GMT). No. of bitstreams: 1 Nasario_JoaoPauloSardin_M.pdf: 1858989 bytes, checksum: 1fd7e7dcb1a5473c4ff7fb12d1cd1a15 (MD5) Previous issue date: 2014 / Resumo: Tradicionalmente incluso na extinta família Bombacaceae, Pseudobombax Dugand pertence à subfamília Bombacoideae, Malvaceae sensu lato. Abrange cerca de 29 espécies, das quais 16 ocorrem em território brasileiro e nove são endêmicas. No Brasil, a maioria das espécies é encontrada no sudeste, planalto central e nordeste. As espécies possuem considerável valor comercial, por serem utilizadas no mundo todo, principalmente na ornamentação e arborização urbana. Estudos sobre o sistema reprodutivo e citogenéticos são raros para o gênero. Com este trabalho, objetivou-se o estudo da biologia floral e reprodutiva, assim como a análise cariotípica de três espécies de Pseudobombax da região sudeste do Brasil. As espécies de Pseudobombax são importantes fontes de pólen e néctar para seus visitantes florais, especialmente por florescerem na estação seca. Algumas diferenças foram observadas entre os períodos de floração e frutificação durante os dois anos de estudo, as quais podem estar relacionadas a diferentes quantidades de chuva antes do início da floração. As flores apresentam antese crepuscular/noturna, com características que se encaixam na síndrome da quiropterofilia. As flores de P. tomentosum são significativamente diferentes das demais espécies (maior comprimento da flor, das pétalas, do ovário e do cálice), porém a forma e o indumento dos frutos é a principal característica que podemos utilizar para separar taxonomicamente as três espécies. Os estudos reprodutivos das três espécies evidenciaram alta porcentagem de fecundação cruzada, indicando alogamia. A eficácia reprodutiva manteve-se alta, confirmando a necessidade de polinização cruzada e, consequentemente, de seus polinizadores. As análises citogenéticas mostraram contagens inéditas, com 2n=88 para Pseudobombax sp. (nova) e P. tomentosum e 2n=84 para P. grandiflorum. O número básico sugerido para as espécies de Pseudobombax é x=44. Foi confirmado mais de um número cromossômico no gênero, o que sugere a derivação por disploidia, decorrente de possíveis rearranjos cromossômicos. Pseudobombax sp. (nova) e P. grandiflorum, espécies muitas vezes confundidas entre si, possuem números cromossômicos diferentes (2n=88 e 2n=84, respectivamente) sendo este um caráter adicional importante na separação taxonômica das duas espécies. O bandamento CMA/DAPI evidenciou um padrão conservado dentro do gênero, com seis bandas CMA+ nas três espécies. Os valores métricos dos cromossomos das espécies em estudo indicaram um comprimento do complemento cromossômico pequeno, nas quais o menor tamanho cromossômico foi de 0,3 µm em P. grandiflorum e o maior foi de 3,5 µm em P. tomentosum. O diferente número cromossômico, bem como algumas características morfológicas florais e do fruto podem ser utilizadas na separação taxonômica das três espécies de Pseudobombax em estudo, evidenciando assim a existência de uma nova espécie para o gênero / Abstract: Traditionally included in the extinct family Bombacaceae, Pseudobombax Dugand belongs to the Bombacoideae subfamily, Malvaceae sensu lato. Composed by about 29 species, of which 16 occur in Brazilian territory and nine are endemic. In Brazil, most species are found in the southeast, northeastern and central plains. Species have considerable commercial value, for being used worldwide, especially in ornamentation and urban forestry. Studies on the reproductive system and cytogenetics are rare for the genus. This work aimed to study the floral and reproductive biology, as well as analysis of karyotype of three species of Pseudobombax from southeastern Brazil. The Pseudobombax species are important sources of pollen and nectar for their floral visitors, especially by flourishing in the dry season. Some differences were observed between the periods of flowering and fruiting during the two years of study, which may be related to different amounts of rainfall before flowering. The flowers have crepuscular/nocturnal anthesis, with features that fit in the chiropterophily syndrome. The flowers of P. tomentosum are significantly different from the other species (greater length of the flower petals, the ovary and the cup), but the shape and indumentum of the fruit is the main feature that we can use to separate the three species taxonomically. Reproductive studies of the three species showed a high percentage of outcrossing, indicating outcrossing. The reproductive efficiency remained high, confirming the necessity of cross-pollination and, therefore, their pollinators. Cytogenetic analysis showed unprecedented chromosome counts, with 2n=88 to Pseudobombax sp. (new) and P. tomentosum and 2n=84 for P. grandiflorum. The basic chromosome number suggested to Pseudobombax is x=44. We confirmed more than one chromosome number in the genus, which suggests derivation by disploidy, due to possible chromosomal rearrangements. Pseudobombax sp. (new) and P. grandiflorum, species often confused with each other, presented different chromosome numbers (2n=88 or 2n=84 , respectively) which is an important taxonomic character for the separation of the two species. The CMA/DAPI banding showed a conserved pattern within the genus, with six CMA+ bands in all species. The metric values of the chromosomes of the species under study indicated a small chromosomal complement length, wherein the smallest chromosome size was 0.3 µm in P. grandiflorum and the largest was 3.5 µm in P. tomentosum. The different chromosome numbers, as well as some floral and fruit morphological characteristics can be used for taxonomic separation of the three Pseudobombax species under study Pseudobombax, thus revealing the existence of a new species for the genus / Mestrado / Biologia Vegetal / Mestre em Biologia Vegetal
279

Influence of Habitat on the Reproductive Ecology of the Amazonian Palm, Mauritia flexuosa, in Roraima, Brazil

Khorsand Rosa, Roxaneh S 21 March 2013 (has links)
Although Mauritia flexuosa (Arecaceae) plays a pivotal role in the ecology and economy of the Amazon, and occurs in a variety of habitats, little is known about the influence of habitat on the reproductive biology of this palm. My dissertation focuses on the reproductive biology of M. flexuosa in three habitats in Roraima, Brazil: undisturbed forest, undisturbed forest-savanna ecotone, and savanna disturbed by plantations of the exotic tree, Acacia mangium. First, I calculated sex ratios and linked precipitation patterns with phenology. Sex ratios were female-biased. Precipitation was negatively associated with flowering, and positively associated with fruiting. Habitat appears to have no significant influence on phenology of M. flexuosa, although short-term climate variation may affect phenology of this species. Second, I examined floral biology, observed floral visitors, and performed exclusion experiments to determine the pollination system of M. flexuosa. Fruit set did not differ significantly between the visitor exclusion treatment and the control, but was significantly lowest in the wind + visitor exclusion treatment, suggesting that this dioecious palm is anemophilous, independent of habitat. Third, I identified the abiotic and biotic factors explaining variation in fruit mass, seed mass, seed number per fruit, and total fruit yield among habitats. Soil moisture and flooding during the wet season were the best predictors of fruit and seed output. The number of leaves, diameter at breast height, and height were all accurate predictors of reproductive output, but crown volume did not accurately predict fruit yields. Results re-evaluate traditional assumptions about wind-pollination in the tropics, and highlight abiotic and biotic factors responsible for variation in reproductive output of M. flexuosa, with implications for effective management of this palm. Finally, I interviewed harvesters and vendors to document the traditional knowledge and market dynamics of the fruit of M. flexuosa, buriti. Traditional knowledge corroborated results from scientific studies. Vendors argued that the price of buriti must increase, and must fluctuate with varying supply. With appropriate economic incentives to vendors/harvesters, Roraima may expand its market infrastructure for buriti, effectively stimulating the regional economy and practicing sustainable harvesting.
280

Reproductive strategies in Melastomataceae = study cases with different approaches = Estratégias reprodutivas em Melastomataceae: estudos de caso com diferentes abordagens / Estratégias reprodutivas em Melastomataceae : estudos de caso com diferentes abordagens

Brito, Vinícius Lourenço Garcia, 1985- 26 August 2018 (has links)
Orientador: Marlies Sazima / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T20:24:29Z (GMT). No. of bitstreams: 1 Brito_ViniciusLourencoGarcia_D.pdf: 4957816 bytes, checksum: 940ef8f4522f7c83d44d482b1e307c27 (MD5) Previous issue date: 2015 / Resumo: Uma estratégia reprodutiva pode ser entendida como um conjunto de características morfo-fisiológicas que são determinantes para a reprodução do organismo e, consequentemente, para sua aptidão. Como a maioria das espécies da família Melastomataceae apresenta anteras poricidas e apenas pólen como recurso, esses grãos de pólen devem cumprir uma dupla função: ser a unidade de transporte do gameta masculino da planta e alimento para os visitantes florais. Assim, em plantas desta família, diferentes estratégias reprodutivas podem ter sido favorecidas como solução para o que ficou conhecido como "dilema de pólen". Nesta tese descrevemos algumas estratégias reprodutivas e discutimos suas possíveis causas e consequências em quatro estudos de caso que envolvem: 1) a fenologia reprodutiva das espécies de Melastomataceae ocorrentes em áreas de Mata Atlântica e Cerrado; 2) a dinâmica de néctar e pólen em Miconia theizans e seu papel no aumento do espectro de visitantes florais e consequente incremento do sucesso reprodutivo feminino; 3) a estrutura e diversidade genética em populações da mesma espécie ocorrente em extremos de um gradiente de altitude com diferentes dinâmicas de polinização e; 4) a mudança de cor em Tibouchina pulchra considerando o aparato visual-cognitivo das abelhas polinizadoras. Além disso, também apresentamos uma revisão sobre a ecologia cognitiva da polinização como um anexo ao quarto estudo. Os resultados obtidos separadamente em cada um destes trabalhos são discutidos em um contexto ecológico-evolutivo e podem ser extrapolados para outros grupos de plantas em que predomina o sistema de polinização dependente de abelhas baseado na oferta de apenas pólen como recurso / Abstract: A reproductive strategy could be understood as complex of morphological and physiological traits involved in plant reproduction and, therefore, in its fitness. As the majority of species of the family Melastomataceae has poricide anthers and offers just pollen as reward to flower visitors, this pollen may face a double fate: be the male reproductive transport unit and food for flower visitors. Therefore, in plants belonging to this family, different reproductive strategies should have been favoured to solve this "pollen dilemma". In this thesis, we describe some reproductive strategies and discuss their possible causes and consequences in four different study cases. The first one is about the reproductive phenology of species of Melastomataceae occurring in the Atlantic rainforest and Cerrado formations. The second study describes the nectar and pollen dynamics in Miconia theizans and its role in favouring the increase of visitor spectra and female reproductive success. The third describes the genetic structure and diversity of populations of Tibouchina pulchra occurring in extremes of an elevational gradient with different pollination dynamics. The fourth is concerned with the floral colour change phenomenon in the same species when considering the visual apparatus of the bees. We also present a review about the cognitive ecology of pollination as an appendix to the fouth study. The results of each study case are discussed in an eco-evolutionary context and may be extrapolated to other angiosperm groups that rely on bees for their pollination and offer just pollen as reward / Doutorado / Biologia Vegetal / Doutor em Biologia Vegetal

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