Dissertations / Theses: 'Pollination ecology'

1

Scodanibbio, Lucia. "Pollination ecology of Mesembs." Bachelor's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/21944.

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Mesembryanthemaceae is one of the main plant families in the Succulent Karoo biome of South Africa. While its pollination ecology still remains largely unstudied, the system is thought to be overall generalised. This study sought to verify whether Mesemb species flowering during September and October in Vrolijkheit Nature Reserve have generalised or specialised pollination interactions. The determinants of insect choice to a particular plant species were investigated and possible mechanisms adopted by different plant species to prevent interspecific pollen transfer were explored. The system was found to have a generalisation level of 24.7%, indicating that one of four possible interactions actually took place. A relatively high degree of overlap in insect visitors was found between the three white-flowered species (Mesemhryanthemum longistylum, Phylloholus grossus and P. splendens). Colour was one of the main determinants of insect choice, whereby Drosanthemurn speciosum, the only red-flowered species in the study showed the highest degree of specialisation. Both scent and nectar production were relatively important in attracting flower visitors. Seasonality in flowering appeared to be a very important mechanism used to reduce overlap in insect visitors, especially among intrageneric species and those that had flowers of the same colour. Daily patterns in scent and nectar production also appeared to play a role in lowering pollinator-sharing. Given the general floral structure of most Mesemb flowers, these mechanisms are likely to be very important in contributing to species reproductive isolation and the low occurrence of hybrids recorded in natural conditions.

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2

Davila, Yvonne Caroline. "Pollination ecology of Trachymeme incisa (Apiaceae) understanding generalised plant-pollinator systems /." Connect to full text, 2006. http://hdl.handle.net/2123/1896.

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Thesis (Ph. D.)--School of Biological Sciences, Faculty of Science, University of Sydney, 2006.
Title from title screen (viewed 15 January 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Biological Sciences, Faculty of Science. Includes bibliographical references. Also available in print form.

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3

Davila, Yvonne Caroline. "Pollination ecology of Trachymene incisa (Apiaceae): Understanding generalised plant-pollinator systems." Thesis, The University of Sydney, 2006. http://hdl.handle.net/2123/1896.

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Abstract:

A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.

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4

Davila, Yvonne Caroline. "Pollination ecology of Trachymene incisa (Apiaceae): Understanding generalised plant-pollinator systems." University of Sydney, 2006. http://hdl.handle.net/2123/1896.

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Abstract:

Doctor of Philosophy (PhD)
A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.

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5

King, Caroline. "Putting pollination quality into analyses of floral ecology : testing syndromes through pollinator performance." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3219.

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Over recent years, the extent of specialised and generalised plant-pollinator relationships, and the predictive powers of floral traits (often grouped into “pollination syndromes”) as indicators of the most effective pollinators of plant species, have been questioned. Such studies, however, have used proxies such as visitation frequency rather than direct measurements of pollinator effectiveness (PE). The main objective of this thesis was to test the predictive powers of various pollination syndromes using a specific measure of PE: single-visit stigmatic pollen deposition (SVSPD). Six different classical pollination syndromes were tested, using 13 different plant species from tropical and temperate habitats, and in the case of flowers typical of the hummingbird, hoverfly, bee, oil flower and long-tongued insect syndromes, the expected pollinators were the most effective at a single-visit scale. For generalist pollination syndrome flowers, not all observed visitors were significant pollinators, and the species studied were not as broadly generalised as their visitor assemblages would suggest. In all 13 plant species, pollinator performance could appear consistent within functional visitor groups but was variable between visitor species, and in almost all cases not all of the observed visitors were effective pollinators. The pollinator performance proxies of visit duration and feeding behaviour were neither significantly, nor consistently, related to PE. Visit duration was not an accurate indicator of pollinator performance on its own, though it was useful when combined with SVSPD to define pollinator performance at a given time scale, for example per hour, per day or per season. My findings suggest that the results of recent “pollination” networks and webs, based on visitors but not necessarily pollinators, should be treated with caution. SVSPD therefore proved to be an effective and relatively simple direct measure of PE, confirming the predictive powers of pollination syndromes, and giving further insight into the extent of specialisation and generalisation.

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6

Raine, Nigel. "The pollination ecology of a Mexican Acacia community." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393473.

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7

Walsh, Ryan Patrick. "Pollination Ecology and Demography of a Deceptive Orchid." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1372097140.

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8

Letten, Andrew. "The ecology of rodent pollination in Liparia parva (Fabaceae)." Bachelor's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/26508.

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The evolution of non-flying mammal pollination has given rise to a broad suite of adaptive plant traits including dull coloured and geoflorous flowers, copious sucrose rich nectar, nocturnal anthesis and nectar production and a musky odour. The Fynbos endemic, Liparia parva (Fabaceae) has been recognised to exhibit several of these traits. Based on this observation, field studies were carried out on the Cape Peninsula, South Africa, to investigate the prediction that L. parva is rodent pollinated. Several lines of evidence indicate that flowers of L. parva are visited by rodents. These include; the presence of Liparia pollen in the faeces of live trapped rodents; observations of captive rodents selectively foraging at flowers of L. parva; floral debris underneath L. parva plants; and video footage captured of a rodent visiting L. parva flowers in the field. However, a strong plant-pollinator relationship was apparent only in the Cape spiny mouse, Acomys subspinosis. Captive Acomys foraged non-destructively at flowers of L. parva, becoming visibly dusted with pollen. The exclusion of rodents from flowers resulted in a significant reduction in seedpod set, indicating rodents do contribute to pollination success in L. parva. Additional evidence that L. parva is adapted to pollination by rodents includes nocturnal floral anthesis and large amounts of total nectar in inflorescences. The findings of this study provide substantial evidence for rodent pollination in L. parva and thus represent the first report of rodent pollination in a legume.

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9

Scaccabarozzi, Daniela. "Pollination Ecology and Pollination Evolutionary Processes with Relevance in Ecosystem Restoration – Pollination Biology of Diuris: Testing for Batesian Mimicry in Southwestern Australia." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/77285.

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The thesis demonstrates a unique pollination system in the Australian orchid genus Diuris via floral mimicry of multiple pea plants (Faboideae). In order to frame the pollination ecology of the putative model pea plants, we also verify the type of pollinator interactions (generalised vs specialized), occurring in communities of pea plants in the southwestern Australian Floristic Region (SWAFR). Our findings support one of the rare confirmed case of guild mimicry in plant world.

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10

Stout, Jane Catherine. "The foraging ecology of bumblebees." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299266.

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11

Prescott, Matthew. "The pollination ecology of a south-eastern Australia Acacia community." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422674.

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12

Levin, Rachel Ann. "Relationships among fragrance, phylogeny and pollination in southwestern Nyctaginaceae." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280128.

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Fragrances appear to act in conjunction with visual cues to attract specific pollinators. Besides the ecological influence of pollinator type on fragrance, as with many other attributes of organisms, phylogenetic history may also affect fragrance composition. In this dissertation I examine the quality and quantity of floral and vegetative fragrance, and explore the relationships among fragrance, pollinators, and phylogenetic history in the plant family Nyctaginaceae. Using DNA sequence data, I inferred phylogenetic relationships among and within the Nyctaginaceae genera Acleisanthes, Selinocarpus, and Mirabilis. There is a high incidence of hawkmoth pollination within these genera, in addition to multiple pollinator transitions. Results suggest that neither Acleisanthes nor Selinocarpus are monophyletic, but that together they comprise a monophyletic lineage. Because of this finding, I have taxonomically combined these two genera into a single genus. Analyses of floral and vegetative fragrance from Acleisanthes, Selinocarpus, and Mirabilis species included in the phylogenetic study show that each species has a unique fragrance profile. Further, although there is substantial variation among individuals within species, intraspecific variation is significantly lower than interspecific variation in fragrance profiles. Fragrances are composed of 5--108 different compounds from at least seven different biosynthetic classes. Some species produce most of their fragrance vegetatively, while floral emissions are the sole source of volatiles in other taxa. Results show that neither total amount of volatiles nor the amount of floral volatiles per mug floral tissue is correlated with pollinator type. However, the emission of nitrogen-bearing compounds appears to have been lost in those lineages that have also lost moth pollination, suggesting that the presence of nitrogen-bearing compounds may be important for moth attraction. Although the phylogenetic signal in the fragrance data is not entirely congruent with the signal in the DNA sequence data, certain compounds and biosynthetic pathways do support the independent phylogeny inferred using the DNA data. However, it is also clear that many compounds are highly homoplastic, yielding limited phylogenetic information. Overall results suggest that phylogenetic relationships rather than pollinator affinities are better predictors of fragrance composition among these Nyctaginaceae species.

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13

Huda, Mohammed Kamrul. "Diversity, ecology, reproductive biology and conservation of orchids of south east Bangladesh." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327403.

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14

Randall, John L. "Pollination ecology of the simultaneously flowering Impatiens capensis and I. pallida." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/49929.

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In mixed stands of the annual Impatiens capensis and I. pallida, bumblebees visit I. pallida almost exclusively even when the nutritional reward of I. pallida is removed. This phenomenon contradicts certain models proposed for foraging behavior in simultaneously flowering species and those dealing with optimal foraging. Such foraging behavior could have potentially devastating effects on the nonpreferred species, especially if the plant is an annual. Both Impatiens species share the same primary pollinators when they grow allopatrically, but when they grow sympatrically I. pallida continues to attract bumblebees while I. capensis depends on hummingbirds and small bees for pollination. Thus competition for pollinators between these Impatiens represents an important plant-plant and plant·pollinator interaction with potential consequences. When I. capensis is less frequented by bumblebees when sympatric with I. pallida, I. capensis exhibits reduced fecundity. Mechanisms of interference through improper pollen transfer are described for the Impatiens species. Pollen of I. pallida adheres to and germinates on the stigmas of I. capensis and the pollen tubes reach the ovules. In contrast, pollen of I. capensis adheres poorly to I. pallida stigmas and fails to germinate. No hybridization occurs between the species. Scanning electron micrographs of pollen and stigma surfaces of the two species revealed no morphological differences. Among the floral characteristics examined, only flower color appeared to influence bumblebee preference for I. pallida. Differences between the species in ultraviolet absorbance patterns, perianth size and shape, odor, and nectar quantity and quality did not affect the pollinator preference of bumblebees. Differences in nectar characteristics and production rate were found among Impatiens populations. However, nectar quantity, quality, and production rates did not differ within allopatric or sympatric populations, but both species had higher nectar volumes with lower solute concentrations in the morning, and lower nectar volumes with higher solute concentrations in the late afternoon. Differences in nectar volumes among populations appeared to be associated with environmental factors affecting population sites. I. capensis avoids competition and maintains itself in sympatric populations with I. pallida by depending on hummingbirds and insects other than bumblebees as pollinators, and has the ability to produce cleistogamous flowers and their subsequent progeny to ensure sexual reproduction. However, inbred progeny of I. capensis are competitively inferior to outcrossed stock. Nevertheless, I. capensis does persist in mixed stands of I. pallida despite the absence of bumblebee pollination and the presence of lower seed set.
Ph. D.
incomplete_metadata

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15

Chirango, Yolanda Tendai. "The pollination and scent ecology of selected Cape milkweeds (Apocynaceae: Asclepiadoideae)." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25205.

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Milkweeds (Asclepiadoideae, Apocynaceae) possess a complex floral morphology that has made them prime candidates for investigating the evolution of plant-pollinator relationships. In South Africa, the pollination ecology of this diverse group has largely been focused in the summer rainfall region. This study focused on Western Cape species in the winter and summer-winter rainfall transition zones. The aim was to determine the pollinators of the study species and assess, describe and quantify their floral attractants. Thus offering a basis of comparison with the previously studied summer rainfall species. The pollination systems of seven milkweed species occurring in the Western Cape were investigated by determining floral visitors and several floral traits that may act as attractants of these visitors. For each study species an attempt at pollinator observations was carried out in several sites across the Cape; floral scent samples were collected through headspace sampling and analysed using GC-MS (gas chromatography-mass spectrometry); floral colour was analysed using spectral reflectance measurements; and nectar was measured to quantify floral rewards. Some Cape milkweeds displayed a more generalized pollination system compared to their summer rainfall congeners. A diverse range of visitors were observed on two Gomphocarpus species, Gomphocarpus cancellatus and G. filiformis in the Fynbos and Succulent Karoo biomes respectively, in contrast to their summer rainfall congeners, which are exclusively wasp pollinated or much less generalized. These two Gomphocarpus species offered floral visitors nectar as a reward with a concentration of 53% in G. cancellatus and a lower 15% in G. filiformis. The species emitted very different scents, G. cancellatus produced a scent dominated by irregular terpenes while G. filiformis scent largely consisted of benzenoid compounds. Although visited by a variety of different insect families and lesser-double collared sunbirds, honeybees and Balbyter ants were found to be the most efficient at removing pollinaria from G. cancellatus and G. filiformis respectively. Eustegia minuta, a Cape endemic, is almost exclusively pollinated by bibionid flies. This is the first record of the pollinators for this monotypic genus, as well as the first for the tribe Eustegieae. Additionally, this study is the first record of a milkweed-bibionid pollination system. The flowers produced very low nectar volumes, displayed minimal visual cues but produced a strong pungent odour dominated by an unidentified compound. This strong scent is thought to play an important role in attracting bibionids while also deterring other potential visitors. The scent profiles of four other previously unstudied Cape milkweeds, namely Cynanchum obtusifolium, C. zeyheri, Fockea capensis and Secamone alpinii were also analysed and shown to be mainly dominated by monoterpenes and benzenoids. Their scent profiles differed markedly from each other as well as to their congeners. The presence of skatole in S. alpinii suggests that it may attract coprophagic flies, small Nematoceran flies were observed drinking nectar from its flowers. While F. capensis produced scent associated with moths. Further observations are needed to confirm true pollinators for both species. The two Cynanchum species produced scent that was very different to each other as well as their congeners. Cynanchum obtusifolium is known to be bee pollinated however its scent profile did not align with this. While C. zeyheri produced a benzenoid-dominated scent with compounds associated with moths. Scent appears to be the most prominent pollinator attractant in the study species compared to floral colour. The concentration and volume of nectar rewards may also be significant. The structural complexity of the flowers is suggestive of a strong floral filter in some species (e.g. Eustegia minuta). Morphologically similar species were found to employ vastly different floral chemical strategies to attract but possibly also deter and filter out floral visitors. The Cape milkweeds therefore offer many opportunities for further pollination studies.

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Teixeira-Martins, Kyle. "Pollination services are mediated by bee functional diversity and landscape context." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121418.

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Wild bees, which exhibit multiple functional traits enabling pollination of apples (Malus domestica Borkh), potentially can compensate for recent declines in domesticated honey bees (Apis mellifera Linnaeus) that are conventionally employed to ensure apple fruit and seed set. Whether compensation is possible will depend on functional diversity in the wild bee community and on the distribution of habitat and resources within the landscape surrounding an orchard that affect wild bee abundance. We studied pollination services and bee functional diversity in 20 apple orchards in southern Quebec, Canada. We evaluated pollinator efficacy by studying: apple visitation rates, approach (front or side-working), body size, foraging type (pollen or nectar foraging), sociality, temporal and climatic activity patterns, and pollen carrying habit. Pollination services were measured as apple fruit set and seed set. A distance-based measure of functional diversity, calibrated with bee traits and weighted by relative abundances in the wild bee community, was used to model pollination services. We correlated the landscape composition and configuration of surrounding natural (forest) and semi-natural (meadow) habitats with bee diversity and pollination services. The incidence of fruit set and seed set in orchards increased with bee functional diversity. Complementarity between managed versus unmanaged bees in traits associated with foraging and resource use drove this relationship. Seed set was also negatively correlated with both the mean distance from surrounding meadows and the total area of surrounding orchards. Bee functional diversity was positively associated with surrounding meadow and forest area. These two land classes complement each other in their seasonal provision of foraging resources for bees. Our models can be used to prescribe management and conservation objectives for meadow and forest habitats that promote bee functional diversity and in turn pollination services. We identify useful wild bee pollinators and discuss their needs in terms of landscape composition and configuration.
Les abeilles sauvages, qui possèdent plusieurs caractéristiques fonctionnelles contribuant à la pollinisation des pommiers (Malus domestica Borkh), ont le potentiel de compenser le déclin d'abeilles mellifères (Apis mellifera Linnaeus) qui sont normalement adoptées pour assurer la grenaison et la nouaison des fruits. Les facteurs qui rendront possible cette dite compensation dépendent de la diversité fonctionnelle de la communauté des abeilles sauvages, ainsi que de la répartition de leur habitat au sein du vaste paysage qui entoure les vergers. Nous avons étudié les services écosystémiques et la diversité fonctionnelle des abeilles dans vingt vergers situés au sud du Québec. Nous avons ensuite évalué l'efficacité des abeilles pollinisatrices en étudiant les paramètres suivants : la vitesse de butinage, la fréquence des contacts avec les stigmates, la taille des abeilles, le type de récolte (pollen ou nectar), la sociabilité, le seuil d'activité en fonction des paramètres climatiques et temporaux, et finalement, le mode de transport du pollen. Les services de pollinisation ont été mesurés en fonction de la nouaison et de la grenaison des pommes. La diversité fonctionnelle a été estimée en tenant compte des caractéristiques fonctionnelles et des valeurs d'abondance relative des abeilles, et cette estimation a été utilisée pour modéliser les services écosystémiques. La composition et la configuration des habitats naturels (boisés) et semi-naturels (en friche) dans les paysages autour des vergers étudiés ont été corrélées avec la diversité et les services de pollinisation fournis localement. L'incidence de la nouaison et la grenaison des pommes ont augmenté avec la diversité fonctionnelle des abeilles. La complémentarité dans l'utilisation des ressources entre les abeilles gérées et non gérées a été responsable de cette relation positive. La diversité fonctionnelle des abeilles a démontré une association positive avec la terre boisée et avec la terre en friche. La phénologie des espèces fleurissantes dans ces deux types de terrain se complète mutuellement dans leur fourniture des ressources pour les abeilles. Nous voulons mettre en place des objectifs de conservation des habitats boisés et en friche afin de favoriser la diversité fonctionnelle des abeilles sauvages et les services de pollinisation. Une identification des espèces d'abeille sauvage les plus utiles à la pollinisation a été entamée, et nous avons discuté de leurs besoins en fonction de la composition et de la configuration du paysage.

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17

Dicks, Lynn V. "The structure and functioning of flower-visiting insect communities on hay meadows." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249064.

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18

Coombs, Gareth. "Ecology and degree of specialization of South African milkweeds with diverse pollination systems." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1003758.

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Like orchids, the complexity of flowers found in asclepiads (Asclepiadoideae, Apocynaceae) and the fact that pollen is presented as pollinaria, offers excellent opportunities to study various aspects of plant-pollinator interactions. In this thesis I investigated two broad themes: ecological aspects of the pollination biology of hymenopteran and fly-pollinated asclepiads as well as the degree of specialization to certain pollinators in these species. Colonizing plants often reproduce through self-pollination, or have highly generalized pollination systems, or both. These characteristics facilitate establishment in small founding populations and generates the prediction that reproductive success should be independent of population size in these species. Chapter one examines the pollination biology of Gomphocarpus physocarpus, an indigenous, weedy species and investigates the relationship between reproductive success and population size. In this species, there is no evidence of an Allee effect and reproductive success is not correlated with population size. In addition G. physocarpus is not capable of self-pollination, suggesting it is completely reliant on pollinators for seed set. The lack of a relationship between pollination success and population size is therefore likely explained by the generalized wasp pollination system of this species. Several milkweeds are invasive outside of their native ranges. Invasive species either need to co-opt native pollinators in order to reproduce or reduce their reliance on pollinators through having the ability to self-pollinate. Co-opting native pollinators is expected to be easier in species that have generalized pollination systems, alternatively species with specialized flower morphologies need to rely on similar functional groups of pollinators to be present within the invaded range. Chapter two investigates the pollination biology and pollination success of the invasive milkweed, Araujia sericifera, and finds that in South Africa, this species is visited mainly by native honeybees and nocturnal moths. Moths however contribute little to pollen removal, and deposition. Based on the apparent morphological mismatch between the flower of A. sericifera and native honeybees, I propose that the native pollinators of this species are likely to be larger Hymenoptera (e.g. Bumblebees). Data from a breeding system study, indicated that this species is not capable of automatic self-pollination, but could set fruit from geitonogamous self-pollinations pointing to the importance of native pollinators for successful reproduction. The pollinaria of milkweeds can accumulate on pollinators to form pollen masses large enough to physically interfere with the foraging behaviour of pollinating insects. In chapter three I describe the pollination biology of Cynanchum ellipticum and find that this species is mainly pollinated by honeybees although this species is visited by several other members of Hymenoptera, Lepidoptera and Diptera. Due to the structure of the pollinaria, these chain together relatively efficiently and frequently form large pollinarium loads on the mouthparts of honeybees. However there is little evidence that these pollinarium loads influence the foraging times of pollinators and only a few individual honeybees exhibited longer foraging times and most honeybees were unaffected by the presence of large pollinarium loads. Within the genus Cynanchum there is large variation in the gynostegium structure that may influence the pattern of pollinarium loading on pollinators as well as pollen reception as shown in chapter three. In Chapter four, the pollination biology of Cynanchum obtusifolium is examined, and like that of C. ellipticum, this species is visited by a wide diversity of pollinators but honeybees appear to be the primary pollinators. More importantly this species is shown to be andromonoecious and produces two morphologically different flower types, that may be distinguished based on differences in the gynostegium structure. These two types of flower could mainly be distinguished by the length of the anther wings. I found that flowers with short anther wings function as male flowers by only exporting- and rarely receiving pollinia. Flowers with longer anther wings function as hermaphrodite flowers and can both export and receive pollinia. The ratio of male to hermaphrodite flowers varied at different times during the flowering season, but preliminary data suggested that this was not related to levels of pollination success. The genera Stapelia and Ceropegia are well known for their intricate floral adaptations that mimic the brood and feeding substrates of pollinating flies. Despite several studies that have documented the various adaptations to fly pollination in different species, there is a lack of natural history studies documenting different flower visitors, pollen loads and long term levels of pollination success in these species. In Chapter six I document the pollination biology of Ceropegia ampliata by documenting different pollinators and quantifying average levels of pollination success and the nectar reward. I also experimentally manipulated the trapping hairs of this species to determine whether trapping hairs influence average levels of pollen export and receipt. I show that Ceropegia ampliata is pollinated by a generalist guild of flies (mainly Tachinidae, Sarcophagidae, Muscidae and Lauxaniidae) and produces minute quantities of relatively dilute nectar as a reward. Pollination success was generally low in this species and increases periodically suggesting that the abundance of pollinators is patchy. I found that flowers with trapping hairs that had already wilted had higher levels of pollinarium removal than flowers with erect hairs, however experimentally removing the hairs had no significant effect on pollen export and receipt. In Chapter seven, I document the pollinators, pollen loads and long term levels of pollination success in Stapelia hirsuta var. bayllissi, a rare sapromyiophilous stapeliad. I find that, in contrast to C. ampliata, this species was specialized to pollination by small flies of the family Anthomyiidae. Similar to the results from Chapter seven, I find that long term levels of pollination success were typically low but could increase periodically, although such increases were generally unpredictable. There are currently very few records documenting pollinator interactions in the Periplocoideae. Many species within this subfamily exhibit open-access flowers suggestive of pollination by short-tongued insects. I investigated the pollination biology of Chlorocyathus lobulata, a rare species with a highly localized distribution. I aimed to determine the pollinators, average levels of pollination success and demography of this species in order to determine whether this rare species is suffering from the collapse of a highly specialized pollinator mutualism. I also quantified the high incidence of flower herbivory caused by larvae of the moth, Bocchoris onychinalis. I find that C. lobulata has a highly generalized fly pollination system and average levels of pollination success suggested that a large proportion of flowers had pollen removed and deposited suggesting that this species is not experiencing pollination failure. The large numbers of juveniles present also indicated that recruitment is taking place.

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Boyd, Amy Elizabeth. "Evolution of floral traits: Biogeography, pollination biology and phylogenetics in Macromeria viridiflora." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279781.

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Macromeria viridiflora is an herbaceous perennial in which floral traits vary geographically. In my dissertation research, I analyzed geographic variation in plant morphology and pollinator assemblages. I conducted experiments to determine the breeding system of the plants, and used visitation rate and pollen deposition to compare effectiveness of floral visitors as pollinators. I analyzed aspects of pollinator attractants and rewards in the flowers and placed this into the context of pollinator syndromes. In addition, I used phylogenetic analysis of the genus to determine polarity of change in corolla size within the species. Analysis of morphometric data from eight sites across the range of the species revealed significant among-population variation in vegetative and floral traits. Flower size variation is particularly strong and follows a latitudinal cline. Hawkmoths and hummingbirds were the main floral visitors throughout the range. The large-bodied hummingbirds visiting plants in the southern regions are not present in the northern regions, where flowers are visited by hummingbirds with barely half the body size and much shorter bills. This difference in bill size of hummingbird pollinators mirrors the geographic variation in flower size in M. viridiflora, suggesting that pollinator-mediated selection may be acting upon the species. Flowers of M. viridiflora have several characteristics that fit both the hummingbird and hawkmoth pollinator syndromes, namely copious sucrose-rich nectar and long floral tubes. However, they also have characteristics that correspond with a single major pollinator. This plant therefore presents a compromise floral syndrome that attracts two classes of pollinators. Breeding system studies showed that whereas plants are self-compatible and occasionally produce seed autogamously, pollinators are important for reproductive success in the plants. Combining visitation rate and pollen deposition as measures of pollinator effectiveness, hummingbirds were found to be the most effective pollinators at both sites. Phylogenetic analysis produced a single most parsimonious tree that supports the monophyly of the genus. Mapping of corolla size onto the phylogeny indicates that floral size has changed many times within the genus, and that very large corolla size in southern populations of Macromeria viridiflora has been derived from a smaller-flowered ancestor.

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Robart, Bruce W. Armstrong Joseph E. "The systematics of Pedicularis bracteosa morphometrics, development, pollination ecology, and molecular phylogenetics /." Normal, Ill. Illinois State University, 2000. http://wwwlib.umi.com/cr/ilstu/fullcit?p9986730.

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Thesis (Ph. D.)--Illinois State University, 2000.
Title from title page screen, viewed May 9, 2006. Dissertation Committee: Joseph E. Armstrong (chair), Roger Anderson, Angelo Capparella, Christopher Horvath, Diane Byers. Includes bibliographical references (leaves 223-234) and abstract. Also available in print.

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Lloyd, Samantha M. "The pollination ecology and reproductive success of the Australian shrub Grevillea macleayana." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20070322.163537/index.html.

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22

Heiduk, Annemarie [Verfasser], and Stefan [Akademischer Betreuer] Dötterl. "Chemical ecology of pollination in deceptive Ceropegia / Annemarie Heiduk ; Betreuer: Stefan Dötterl." Bayreuth : Universität Bayreuth, 2017. http://d-nb.info/1144364981/34.

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23

Solis-Montero, Lislie. "Pollination ecology and mating system of Solanum rostratum (Solanaceae) in North America." Thesis, University of Stirling, 2013. http://hdl.handle.net/1893/20352.

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Buzz-pollination or pollination by vibration occurs in several families of angiosperms including some important commercial crops such as potatoes and tomatoes. Buzz-pollinated flowers release pollen via small pores or slits on the anther’s tip that require the use of vibrations by specialized pollinators, usually bees, to remove the pollen. Some buzz-pollinated species have elaborate floral morphologies including dimorphic anthers within the same flower (heteranthery), and mirror-image flowers (enantiostyly) where the style is reciprocally deflected to either the left or right side of the floral axis. The complex floral morphology and buzz-pollination syndrome seen in these species require a close physical interaction between the sexual organs of the flowers and the bodies of insect visitors. Despite the broad taxonomic distribution of buzz-pollination in angiosperms (more than 60 families are buzz-pollinated) relatively few studies have described the pollination ecology of these species under natural conditions. The main goal of the present work was to characterize the pollination biology, mating patterns and antagonistic interactions (e.g. pollen theft) in natural populations of a buzz-pollinated species. For this purpose, I studied Solanum rostratum (Solanaceae), a buzz-pollinated, self-compatible, annual weed with complex floral morphology (both enantiostylous and heterantherous flowers). This species usually grows in disturbed areas in its native range (Mexico) and has become invasive around the world. My research was divided into three components. First, I characterized the pollination and reproductive biology of natural populations in Mexico. I performed floral manipulations in six natural populations of S. rostratum to estimate fruit and seed set. In three of these populations, I carried out 115 hours of pollinator observations and quantified the incidence of pollinators versus pollen thieves. I also measured the efficiency of a subset of floral visitors in triggering fruit set after single visits. Second, I investigated whether morphological correspondence between the size of the pollinator’s body and floral morphology influences pollen transfer. In experimental arrays, I exposed flowers of S. rostratum that varied in the distance between their sexual organs, to bumblebees (Bombus terrestris) of different sizes, and recorded pollen deposition and fruit and seed production. Finally, I determined the mating system (i.e. the proportion of self- and cross-fertilized offspring) of natural populations in Mexico and of introduced populations in the United States of America, using newly developed microsatellite markers. My results show that S. rostratum is visited by a wide range of bees of different sizes (0.9–9.8 mm in thorax diameter), but that only a small subset of these visitors act as pollinators. Most visitors act as pollen thieves, consuming pollen while effecting little or no pollination. I also found that correspondence between a pollinator’s size and the separation of the S. rostratum sexual organs determines pollen deposition and fruit production; pollen deposition decreased when bees were small relative to the distance between the sexual organs visited the flowers. My genetic analyses show that natural populations of S. rostratum maintain a relatively high outcrossing rate (tm = 0.75 ± 0.03) across the native and introduced range. Furthermore, genetic diversity is reduced in invasive populations, but this is not accompanied by changes in mating system. My work shows that the morphological fit between the pollinator and the flowers is important in determining the dynamics of pollen transfer and fruit production in this buzz-pollinated plant. Distinguishing between pollinators and pollen thieves in buzz-pollinated plants is essential for understanding the evolution of buzz-pollination, as pollen theft could be a major selective force for these species.

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Schmucki, Reto. "Demography and pollination ecology of «Trillium grandiflorum» in hedgerow corridors and forest patches." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32367.

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Hedgerows are assumed to provide suitable habitats and dispersal corridors in agricultural landscapes for forest herbs, but these functions have rarely been tested. Assuming that hedgerows can sustain viable populations solely from vegetation survey can be misleading since it does not take into account extinction lag and demographic processes. I address the question of hedgerow's suitability for forest herbs by comparing the demography and pollination biology of Trillium grandiflorum in hedgerow corridors and forest patches of an agricultural landscape. Specifically I ask: Do population structure and individual performance of T. grandiflorum differ between hedgerows and forests? Are pollination services comparable in hedgerows and forests? How do variations in growth, survival, and reproduction influence demography in hedgerows and forests? Individual plant performance and population structure was determined from field observations and experiments conducted in a system of hedgerows connected to forests. I conducted pollination and transplantation experiments to test for variation in pollination and reproduction among habitats and with increasing isolation. Populations monitored for three years in hedgerows and forests were used to construct transition matrix models and to compare their dynamics. Populations in hedgerows were characterized by lower proportion of seedling and juvenile per mature plant, but also by better flower and ovule production than in forests. Pollen limitation was comparable between habitats, suggesting that pollination services in hedgerows are at least as good as in forests. Pollination varied at the landscape scale and over time, and declined wi
Présumer que les haies peuvent servir de corridors de dispersion et contenir des populations d'herbacées forestières viables sur la seule base d'inventaires de la végétation peut être biaisé puisque ceux-ci ne tiennent pas compte du délai d'extinction ni des processus démographiques. J'aborde la question de la qualité des haies en tant qu'habitat en comparant la démographie et la pollinisation de Trillium grandiflorum dans des haies et des forêts. Est-ce que la structure des populations et la performance individuelle diffèrent dans les haies des forêts? Est-ce que les services de pollinisation sont comparables entre haies et forêts? Comment des variations dans la croissance, la survie, et la reproduction influencent la démographie dans chacun de ces habitats? La performance individuelle et la structure des populations ont été dérivées d'observations et d'expériences effectuées en haies et en forêts. Des expériences de pollinisation et de transplantation ont été utilisées pour tester les effets d'habitats et d'isolement sur la pollinisation et la reproduction. Des suivis, effectués en haies et en forêts, durant trois ans ont servi à construire des matrices de transitions et comparer la dynamique des populations. Dans les haies, les semis et les juvéniles sont retrouvés en moins grandes proportions, bien que la production de fleurs et d'ovules y soit plus élevée qu'en forêt. La limitation de pollen ne diffère pas, suggérant que la pollinisation dans les haies est équivalente à celle des forêts. La pollinisation varie à l'échelle des paysages et du temps, ainsi qu'avec l'isolement. La faible survie des premiers stades affecte nég

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25

Jacobs, Jennifer H. "The birds and the bees : pollination of fruit-bearing hedgerow plants and consequences for birds." Thesis, University of Stirling, 2008. http://hdl.handle.net/1893/1319.

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Hedgerow fruits provide a food resource for several UK farmland bird species from late summer, through winter and into spring. This project aims to develop the understanding of the interactions between fruit-bearing hedgerow flowers, their pollinators, hedgerow fruits and frugivorous birds. Experiments revealed that flowers of blackthorn, hawthorn and ivy all benefited from insect visits in order to develop fruit. The flowers of bramble and dog rose showed little requirement for insect pollination, and produced fruit when insects were excluded. There was evidence that for the hedges under study, the pollination service provided by insects to blackthorn and hawthorn flowers was inadequate since the flowers of these plants were pollen limited. The relative abundance of different insect groups foraging on blackthorn flowers was highly variable between hedges, suggesting that the contribution of a particular insect group to blackthorn pollination may vary according to their local density. Bumblebees, bristly flies and solitary bees were considered to have the greatest value for pollinating blackthorn flowers, based on foraging attributes (bumblebees and solitary bees), and abundance (bristly flies), but their activity did not correlate with the proportion of flowers that set fruit. Solitary bee activity correlated with hawthorn pollination, and there was strong evidence that social wasps were the best pollinators of ivy flowers on the hedges studied. Environmental factors such as hedge aspect did not significantly affect the activity of most pollinators (with the exception of solitary bees) or the proportion of blackthorn flowers that set fruit. Equally, the presence of the mass-flowering, attractive forage source, oilseed rape in fields adjacent to hedgerows, did not significantly influence the activity of most pollinators or the proportion of hawthorn flowers that set fruit. The abundance of some frugivorous birds, in particular the migratory thrushes (redwings and fieldfares) was positively related to the yield of fruits, including sloes and haws in hedges. So the evidence suggests that on these farms, pollinator communities are important for ensuring some hedgerow shrubs provide copious fruit, which may be vital for birds during winter months when invertebrate food is scarce. These links between flowers, pollinators, fruits and birds are discussed, alongside suggestions for safeguarding the fruit supply for farmland birds in the future.

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26

Guezen, Jessica. "Past Floral Resources as a Predictor of Present Bee Visits in Agroecosystems." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/37051.

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Relying on wild bees for pollination services has become necessary as the global demand for crops dependent on animal pollination increases. If wild bee populations are to establish and persist in agricultural landscapes, there must be sufficient floral resources over time and space. This study examines the relationship between bee visits in agroecosystems and the spatiotemporal availability of floral resources over one season. I expected that landscapes with greater floral resources earlier in the season would subsequently experience more bee visits than landscapes with fewer early-season floral resources, and that the spatiotemporal scale of this effect would differ among taxa. I measured bee visitation rate and floral resource density over three spatial scales and during four time-periods spanning one season, in 27 agricultural sites across Ontario and Québec, Canada. The present abundance of floral resources at a local scale positively influenced bee visits across all sampling periods. However, differences in the temporal scale of bees’ response to floral resources were observed at landscape scales. Past and present floral resources were positively or negatively associated with bee visits depending on the time of season and which taxon was examined. The number of visits by Andrenidae, honey bees, and bumble bees increased with floral resource abundance in previous time-periods, while other taxa exhibited a negative association with past floral resources, suggesting possible dilution of bee populations at a landscape scale. Understanding the scales at which bee taxa are influenced by floral resources can allow development of land management strategies that could enhance crop pollination and conserve species threatened by agricultural intensification.

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Delnevo, Nicola. "Conospermum undulatum: insights into population genetics and pollination ecology of a threatened species." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2398.

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Fragmentation of natural vegetation is currently one of the largest threats to biodiversity. Within the southwest Australia global biodiversity hotspot, the Swan Coastal Plain was historically cleared for agriculture and forestry and is now experiencing extensive land clearing for urbanisation. The wavy-leaved smokebush Conospermum undulatum is a rare species endemic to the Swan Coastal Plain, and its future persistence is threatened by urban expansion. Throughout this research, I investigated the pollination ecology of this species and found a specific association between C. undulatum and native bees for pollination. I also demonstrated that C. undulatum has evolved pollen with resistance to the usually negative effect of ant secretions on pollen grains, with ants providing effective pollination services to this threatened species. Native pollinators were drastically reduced in small populations, and urbanisation limited the movement of pollen across built-up areas surrounding remnant bushland. This lack of both pollinators and inter-population pollen flow is severely limiting the production of healthy seeds in smaller populations. I then performed molecular investigations combined with an ecological characterisation of the recently fragmented distribution range of C. undulatum to quantify the genetic structure and levels of genetic diversity across the entire distribution of the species. Despite the current intense fragmentation, I found levels of genetic diversity similar across populations and a weak spatial genetic structure. Since habitat fragmentation is recent and many adult plants are likely to be several decades old, they mainly reflect pre-fragmentation conditions. Therefore, the detailed characterization of fragmentation over time has shown how the low levels of genetic fixation can be attributed to pervasive gene flow through the pre-fragmented landscape, which mostly influenced the current adult cohort. Early signals of the negative effects of habitat fragmentation were found during my study of contemporary gene flow through the paternity assignment of seedlings sampled at the end of the 2017 flowering season. Although gametes of C. undulatum could flow unimpeded through large expanses of unfragmented bushland, inter-population pollen flow was non-existent between fragments surrounded by built-up areas. This study supports the need for an understanding of contemporary mating patterns to detect early signals of gene flow failure in fragmented remnants. Lastly, I found evidence for hybridisation occurring at the edge of the distribution of C. undulatum between this rare and threatened plant and two other related species. This adds to the threats posed by habitat fragmentation to the conservation of C. undulatum. My research highlighted the importance of native pollinators for plants that coevolved with them and adds to the limited research on the effect of habitat fragmentation on native plants that rely exclusively on native insects for pollination. Such pollinators appeared unable to maintain an adequate inter- population pollen flow in heavily fragmented landscapes. Therefore, the often negative effects of habitat fragmentation can be exacerbated in small and isolated populations of plants that rely on species-specific pollinators for sexual reproduction. Outcomes of my research will inform recovery plans to enhance the future persistence of C. undulatum over the long term.

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28

Burdine, Justin D. "Factors influencing bee communities and pollination services across an urban environment." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1554460864439054.

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29

Wethington, Susan Marie. "Some effects of variability in nectar renewal-rates on the hummingbird-foraging/plant-pollination mutualism." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284254.

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How does variability in nectar secretion rates affect the interaction between hummingbirds and the plants that: they pollinate? Other researchers have suggested that variability may influence pollinators to leave a plant earlier, thus increasing the potential for cross-pollination. My dissertation asks the following questions: Does variability in nectar secretion rates influence hummingbird visitation at a flower patch? Does it do so in a manner that is likely to increase; cross-pollination? And, does variability in these rates benefit the hummingbird by improving their foraging efficiency? By asking if variability benefits both plants and hummingbirds, I implicitly ask the question: Can variability in nectar secretion rates be a mechanism that helps keep this potentially antagonistic interaction positive? I developed an artificial flower that simulates nectar secretion. Using patches of these artificial flowers, I varied renewal rates of flowers found within a patch. The appendices describe the results of my studies. The aviary experiment (Appendix A) investigates how Broad-billed hummingbirds (Cynanthus latirostris) forage given variability in nectar renewal-rates. The field experiment (Appendix B) investigates how hummingbird visitation to patches with different renewal-rates might affect cross-pollination. Appendix C describes the hummingbird community at the study site. Appendix D identifies the plants visited by these hummingbirds. In the aviary experiment, Broad-billed hummingbirds changed their foraging when exposed to high variability and limited nectar. They visited a higher percentage of rewarding flowers, foraged more systematically, and significantly decreased their foraging time. These changes made their foraging more efficient. In the field experiment, increased renewal-rate variability was associated with hummingbirds visiting fewer artificial flowers per foraging bout. These results suggest cross-pollination may be increased. However, levels of renewal-rate variability did not affect the visitation rates to the flower patch or the distribution of nectar within the patch. Hummingbirds spent significantly more time probing the last flower in a foraging bout than other flowers, and preferentially ended foraging bouts on a rapidly renewing flower. I suggest that the energetic cost of hovering flight likely influenced this behavior. My results support the hypothesis that variability in nectar secretion rates may benefit both partners in this pollination mutualism.

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Brand, Mariette Rieks. "Pollination ecosystem services to onion hybrid seed crops in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86238.

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Thesis (PhD)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Insect pollination contributes in various degrees toward the production of a variety of agricultural crops that ensure diversity and nutritional value in the human diet. Although managed honeybees (Apis mellifera L.) are still the most economically valuable pollinators of monoculture crops cultivated globally, wild pollinator communities can contribute substantially toward crop pollination through pollination ecosystem services sourced from neighbouring natural habitats. Pollination ecosystem services are thus valuable and can motivate for the protection of natural ecosystems hosting diverse insect pollinator communities. F1 onion hybrid seed production is entirely dependent on high insect pollinator activity to ensure cross pollination, seed set and profitable seed yields. Data was collected on 18 onion hybrid seed crops grown in the semi‐arid Klein Karoo and southern Karoo regions of the Western Cape, South Africa. These two main production regions are located within the Succulent Karoo biome, recognized as a global biodiversity hotspot of especially high plant diversity. It is also habitat to the indigenous Cape honeybee (Apis mellifera capensis Esch.). Sites selected varied in the percentages of available natural habitat and managed honeybee hives stocking density. Diverse anthophile assemblages were sampled with pan traps within all the onion fields, regardless of the percentage of available natural habitat near the crop. Crop management practices significantly affected the diversity of anthophile species caught within onion fields, although less than 20% of this diversity was observed actually visiting onion flowers. The honeybee (managed and wild) was by far the most important pollinator because of its high visitation frequency and regular substantial onion pollen loads carried on their bodies. Honeybee visitation significantly increased onion hybrid seed yield, while anthophile diversity and non‐Apis visitation had no effect on seed yield. Neither managed hive density, nor percentage natural habitat were important in determining honeybee visitation or seed yield. Total annual rainfall was the only significant factor determining honeybee visitation. Secondary factors caused by rainfall variability, such as wild flower abundance or soil moisture, may have significantly affected honeybee visitation. In addition, the positive correlation between honeybee visitation and the diversity of hand‐sampled insects from onion flowers; indicate that either or both onion varietal attractiveness and/or pollinator population size may have had significant effects on overall insect visitation. Honeybees showed marked discrimination between hybrid onion parental lines and preferred to forage on one or the other during single foraging trips. Hybrid onion parents differed significantly in nectar characteristics and onion flower scent which would encourage selective foraging through floral constancy. Interspecies interactions were insignificant in causing increased honeybee pollination because of the scarcity of non‐Apis visitors. Most farming practices are subjected to favourable environmental conditions for successful production. However, and especially in the South African context, the dependence of onion hybrid seed crops on insect pollination for successful yields, increase its reliance on natural ecosystem dynamics that may deliver abundant wild honeybee pollinators, or attract them away from the crops. Nevertheless, this dependence can be mitigated effectively by the use of managed honeybee colonies to supplement wild honeybee workers on the flowers.
AFRIKAANSE OPSOMMING: Insek bestuiwing dra in verskillende grade by tot die produksie van landbou gewasse wat variteit en voedingswaarde in die mens se dieet verseker. Al is die heuningby (Apis mellifera L.) steeds die waardevolste ekonomiese bestuiwer van verboude enkelgewasse, kan wilde bestuiwers wesenlik bydra tot gewasbestuiwing deur middel van ekosisteem dienste afkomstig van natuurlike habitatte. Bestuiwing ekosisteem dienste is daarom waardevol en kan dus die bewaring van natuurlike ekosisteme, wat diverse gemeenskappe huisves, regverdig. F1 basterui saadproduksie is totaal afhanklik van hoë insek‐bestuiwer aktiwiteit om kruisbestuiwing, saadvorming en winsgewende saadopbrengste te verseker. Data is ingesamel op 18 basterui saad aanplantings in die half‐droë Klein Karoo en suid‐Karoo streke van die Weskaap, Suid‐Afrika. Hierdie twee hoof produksie streke is geleë binne die Sukkulente Karoo bioom wat erken word as ŉ globale biodiversiteits “hotspot” met hoë plant diversiteit. Dit is ook die habitat van die inheemse Kaapse heuningby (Apis mellifera capensis Esch.). Aanplantings is gekies om verskillende grade van beskikbare natuurlike habitat en bestuurde heuningby korf digthede te verteenwoordig. Diverse versamelings blom‐besoekers is versamel met water‐wippe in al die aanplantings, ongeag die persentasie natuurlike habitat beskikbaar by elke aanplanting. Gewas bestuurspraktyke het die diversiteit van blombesoekers betekenisvol beïnvloed. Tog is minder as 20% van hierdie diversiteit as aktiewe besoekers op die uiekoppe waargeneem. Heuningbye (bestuur of wild) was oorwegend die belangrikste bestuiwers as gevolg van hoë besoek frekwensies en wesenlike ladings uiestuifmeel op hulle liggame. Heuningby besoeke het saadopbrengs betekenisvol verhoog, maar blom‐besoeker diversiteit en nie‐Apis besoeke het geen effek op saadopbrengs gehad nie. Bestuurde korf digtheid en persentasie natuurlike habitat was nie belangrik in die bepaling van heuningby besoeke of basterui saadopbrengste nie. Totale jaarlikse reënval was die enigste betekenisvolle faktor wat heuningby besoeke bepaal het. Sekondêre faktore wat versoorsaak word deur reënval veranderlikheid, soos veldblom volopheid of grondvog, kon betekenisvolle effekte op die aantal heuningby besoeke gehad het. Bykomend, dui die positiewe korrelasie tussen heuningby besoeke en die diversiteit van hand‐versamelde insekte vanaf die uiekoppe op die moontlike betekenisvolle effek van elk of beide basterui variteit aantreklikheid en/of bestuiwer populasie grote op algehele insek besoeke. Heuningbye het noemenswaardige diskriminasie getoon tussen die basterui ouerlyne en het verkies om op een of die ander te wei tydens enkele weidingstogte. Basterui ouerlyne het betekenisvol verskil in nektar eienskappe en blomgeur wat die selektiewe weiding van heuningbye, toegepas deur blomkonstantheid, sal aanmoedig. Tussen‐spesie interaksies was onbetekenisvol in die verhoging van heuningby bestuiwing omdat nie‐Apis besoekers baie skaars was. Meeste boerdery praktyke is onderhewig aan gunstige omgewings toestande vir suksesvolle produksie. Maar, en veral in die Suid‐Afrikaanse konteks, omdat basterui saad aanplantings afhanklik is van insek bestuiwing vir suksesvolle opbrengste, word daar meer staat gemaak op natuurlike ekosisteem dinamika wat volop wilde heuningby bestuiwers kan voorsien, of selfs bestuiwers van die aanplanting kan weg lok. Nietemin, hierdie afhanklikheid kan effektief verlaag word deur die gebruik van bestuurde heuningby kolonies om die aantal wilde heuningby werkers op die blomme aan te vul.

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Jenkins, Miriam M. "Density Effects on Competition for Pollination between Two Wetland Plants." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1405376639.

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32

Holmén, Bränn Kristina. "Pollination processes - maternal and offspring performance." Doctoral thesis, Stockholm University, Department of Botany, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6709.

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Pollination is one of the most important factors determining the reproductive success of plants. This thesis examines processes associated to varying pollination, with focus on plant responses. The first aim was to examine the possibility and constraints for short-term evolution of flower size in Raphanus raphanistrum. The results showed that there exists a possibility for pollinator-mediated short-term evolution of flower size in the study species. Flower size was strongly correlated to plant size. Since flower size cannot evolve separately from plant size, this correlation may constitute a constraint to the evolution of flower size. The second aim was to determine how varying pollen load affects later flowering, reproduction and growth of maternal plants. High pollen load treatment resulted in larger or more flowers on late flowers, which may enhance pollen dispersal and reproductive success, while the total seed mass was the same between treatments. The results indicate that the study species R. raphanistrum, Sinapis arvensis and Brassica napus have plastic responses in floral traits according to the present pollination level. The third aim was to determine how varying pollen load affects seed quality and offspring vigor. The results suggest that high pollen load had no positive effects on seed quality or offspring vigor due to pollen competition. Instead, seed mass determined seed quality and offspring vigor in the three study species and low pollen load treatment resulted in highquality offspring due to heavier seeds. The fourth aim was to examine causes and consequences of variation in reproductive success of Succisa pratensis on a regional scale. The results suggest that the most important variables, on a regional scale, for reproductive success were population size and habitat quality. The results showed that seed weight variation might be important when assessing reproductive success. In this study, seed weight variation did not seem to be adaptive.

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33

Bobiwash, Kyle. "Pollination ecology of lowbush blueberry (Vaccinium angustifolium) - The role of introduced pollinator communities, self-fertilization and somatic mutations on fruit set response." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114589.

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This thesis examines fruit yield variation and its causes in the lowbush blueberry (Vaccinium angustifolium). I found that yields exhibits significant variability in fruit within and between fields. An experiment involving controlled introductions of the three pollinator species commonly used in blueberry production—the honeybee (Apis mellifera), the bumblebee (Bombus spp.) and leafcutter bee (Megachile rotundata)—was also conducted. Increasing the abundance or diversity of the introduced pollinator community did not systematically increase fruit set across the experimental populations. There is weak evidence to suggest the combination of bumblebee and leafcutter bee may be more effective at increasing fruit yield than honeybee alone. The behaviour of introduced pollinator species differed between fields depending on the combination of pollinator species present, however, none of these changes was correlated with increased fruit set. As part of this work, self-pollinations and cross-pollinations were conducted in a large number of clones and variation in inbreeding depression of yield was detected among clones. To evaluate whether differences in accumulated deleterious mutations among clones were responsible for variation in inbreeding depression, a follow-up experiment manipulating access to self pollen was undertaken. In addition, differential genetic load was measured, using clone size as a proxy for somatic cell division. Neither clonal size nor self pollen access sufficiently explained the interclonal variation in self fruit set. Within the same fields, geitonogamously-pollinated fruit set was greater than autogamously-pollinated fruit set. These differences suggest the presence of somatic mutations, cell lineage selection, mitotic recombination, or epigenetic changes within lowbush blueberry clones, and they mirror results from studies of several perennial plant species that have revealed autogamy depression to be a significant factor in plant fertility. These results suggest that self-fertilization is an important element limiting fruit set that should be addressed in attempts to increase lowbush blueberry yield.
Ce thèse explore la variance du rendement de fruit et les causes des différences dans le rendement vue dans l'espèce de bleuet Vaccinium angustifolium. J'ai trouvé qu'il existe une variabilité dans le rendement de fruit entre les champs et entre les individus du champs. Une expérience visant l'introduction des trois espèces pollinisateur utilisé le plus fréquement (Apis mellifera, Bombus spp., Megachile rotundata) au Nouveau-Brunswick a aussi eu lieu. Lors de l'augmentation de la diversité ou l'abondance il n'y avait aucun gain conséquent dans le rendement de fruit. Il y a un faible temoignage qui suggère que le rendement de fruit est plus élevé dans les champs qui inclut la combinaison pollinisateur de Bombus et Megachile comparé au champs seulement avec Apis introduit. Les mesures de comportement des pollinisateur introduit ont aussi varié entre les champs dépendant des espèces présent dans les champs, mais ces changements en comportement n'ont pas été lié au différences dans le rendement de fruit. Comme partie de cette recherche, des auto- pollinisations et des pollinisations croisée ont eu lieu dans plusieurs clones, avec une variabilité dans la dépression de consanguinité vue entre individus. Pour evaluer si des différences dans l'accumulation des mutations somatiques entre individus sont responsable pour la variabilité dans la dépression de consanguinité, une expérience qui a but de modifié accès de auto pollen a suivie. Pour mésurer la différence en charge génétique, la taille des clones a été utilisé pour représenter la division cellulaire somatique. Ni la taille des clones ou l'accès à l'auto pollen fut capable d'expliquer la variation de rendement de fruit entre les clones. Ces mêmes champs on aussi produit un taux de rendement de fruit plus élevé dans les fleurs fécondé avec le pollen geitonogamous comparé au fleurs fécondé avec le pollen autogame. Ces différences suggèrent la présence des mutations somatiques, la sélection lignée cellulaire, la recombinaison mitotique, ou des changement épigénétique dans les clones de bleuets, et ces résulats reflète d'autres études des espèces de plantes vivaces qui indique que la dépression autogame est une force significative dans la fertilié des plantes. Nos résultats suggèrent que l'auto pollinisation joue un rôle important dans la limitation du rendement de fruit et dois être considéré lorsqu'on essai d'augmenter le rendement de fruit chez le bleuet V. angustifolium.

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Wong, Sato Akira Armando. "Diverse adaptations to increase pollination success in zoophilous plants." Kyoto University, 2018. http://hdl.handle.net/2433/232377.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第21176号
人博第848号
新制||人||203(附属図書館)
29||人博||848(吉田南総合図書館)
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授加藤眞, 教授市岡孝朗, 教授瀬戸口浩彰
学位規則第4条第1項該当

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35

Hatjina, F. "The use of 'temporary confinement' and 'pollen transfer devices' to increase pollination potential of honey bees." Thesis, Cardiff University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250390.

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36

Davidson, Jacob B. "Natural History and Breeding System of Maguire Primrose." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/696.

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The goal of this thesis was to examine the breeding system and natural history of the Maguire primrose (Primula cusickiana var. maguirei). Maguire primrose is an endemic, threatened subspecies found only along a narrow corridor within Logan Canyon in northern Utah, USA. This plant displays distinct flower distyly, with clear distinction of pin and thrum morphologies (morphs). The timing of Maguire primrose flower blooms was disparate between upper and lower canyon populations, and the flowers experienced cool temperatures occasionally. I captured eight different species of flying insects visiting Maguire primrose flowers, and made 67 observations of insect visitation. Inter-morph outcrossing hand pollinations were the most successful hand pollinations performed, but were usually not as successful as those that were naturally pollinated. Selfing rates were quite low compared to outcrossing reproductive scenarios. Morph-specific fecundity differences were detected in my hand pollinations, but not in the naturally pollinated maternal plants. I did not observe clear fecundity differences based on the canyon location of Maguire primrose.

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Lewis, Matthew B. "Roads and the Reproductive Ecology of Hesperidanthus suffrutescens, an Endangered Shrub." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1449.

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I investigated the pollination ecology ofHesperidanthus suffrutescens, an endangered Utah shrub, as well as the effects that road dust and local plant density may have on successful reproduction. The breeding system study included four pollination treatments to determine the degree of self-compatibility. Flower visitors were collected and probable pollinators were identified. To determine the effects of road dust on reproduction, I measured dust deposition, plant size, and reproduction in plots of increasing distance from an unpaved road. I also measured dust effects on pollination success and stomatal conductance. I determined the number of individuals per plot and the relative isolation of individuals, and measured their reproductive success to determine any significant effects. Reproduction was measured as total fruit set per plant as well as estimates of total plant seeds and plant seed weight (mg). The results of the pollination treatments and the identity of pollinators are described in Chapter 2. Both autogamy and geitonogamy (selfing treatments) produced substantially and significantly fewer fruits, seeds, and seeds per fruit than xenogamy (outcrossing treatment). Additionally, outcrossed flowers produced significantly more fruits, seeds, and seeds per fruit than did open control flowers with no difference in mean seed weight. In total, 77 flower visitors were collected over the course of the study. Probable pollinators include severalAndrena,Halictus, andDialictusbees. The effects of road dust on the reproductive success ofH. suffrutescensare discussed in Chapter 3. Dust deposition decreased with increased distance from the road and was significantly correlated with decreased fruit set for plants of a given size. Other reproductive metrics showed the same negative patterns although not significantly. The results suggest that dust may disrupt pollination and affect the physiology of plants, resulting in decreased reproduction. Dust deposition did not decrease pollination success of dusted flowers but did negatively impact stomatal conductance of leaves. The main effects of patch size and relative isolation on reproductive success are discussed in Chapter 4. Both patch size and relative isolation had no significant impacts on reproductive success. Increased patch size did indicate negative patterns on reproductive metrics, although not significantly. Similarly, increased isolation indicated increased reproductive success, although not significantly.

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Barker, Cory. "Impacts of an Urbanization Gradient on Pollination Services to a Bee-Pollinated Plant." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38310.

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The vast majority of flowering plants rely on pollinators for outcrossed reproduction. Unfortunately, many species of pollinators are in decline. Pollinators face a number of challenges, including shifting land use, climate change and pesticides. In addition, pollinator habitat may be altered or eliminated through urbanization. Fragmented urban landscapes may lengthen the distances among foraging patches, limit resources in a given patch, and reduce the availability of pollinator nesting sites. Here, I examine the effects of urbanization on pollination services by addressing the following questions: (1) Does bee species richness and/or abundance change along an urbanization gradient?; (2) Does the pollen limitation of a focal species vary along the same gradient?; (3) Do plants with a mixed mating system produce more selfed seeds in more urban environments? Using the percentage of impervious land cover in the space immediately surrounding the site as a proxy for site urbanization, 15 study sites were set up across the city of Ottawa to span a range from minimal percent impervious surface (mostly green space) to mostly impervious surface (little green space) at a range of spatial scales. At each site I set up an array of 20 potted Impatiens capensis plants as well as six pan traps in order to collect data on pollen limitation, seed production, and the number of selfed progeny, in addition to information about local pollinator species richness and abundance. Plants in the arrays were randomly assigned to either a hand or open pollination treatment in order to assess the level of pollen limitation. Surprisingly, pollinator species richness and abundance were not correlated with urbanization. Pollen limitation declined with urbanization, however, so did overall seed set, making it difficult to detangle the effects of resource limitation and hand pollination treatments. The number of selfed seeds produced by a plant was also significantly correlated with site urbanization. Further investigation is required to better understand the dynamics of pollination services in urban environments. I recommend that future studies explore how the presence of individual bee species in rural and urban habitats could be influencing pollen limitation and selfing in I. capensis.

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Nachev, Vladislav Nikolaev [Verfasser], York [Akademischer Betreuer] Winter, Bernhard [Akademischer Betreuer] Ronnacher, and Sue [Akademischer Betreuer] Healy. "Cognition mediated floral evolution : pollinator decision making in a virtual pollination ecology paradigm / Vladislav Nikolaev Nachev. Gutachter: York Winter ; Bernhard Ronnacher ; Sue Healy." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://d-nb.info/1046386328/34.

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40

Bataw, Ali A. M. "Pollination ecology of cultivated and wild raspberry (Rubus idaeus) and the behaviour of visiting insects." Thesis, University of St Andrews, 1996. http://hdl.handle.net/10023/14205.

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Floral morphology and anthesis were studied in commercial and in wild populations of raspberry (Rubus idaeus). Young flowers offered both nectar and pollen, but medium and old flowers offered nectar only, in diminishing quantity. All the three types had similar ageing patterns and diurnal patterns of nectar secretion, but they differed significantly in the nectar standing crop. Variation in nectar secretion rates within the raspberry cultivars was examined; Glen Moy produced more nectar per flower, and more flowers per meter, than Glen Prosen and wild raspberry flowers. There was significant daily variation in secretion rate, individual flowers in all cultivars showing variable rates of secretion even on the same branch. Time of sampling, effects of insect visitors, flower age and weather conditions all showed significant relationships to nectar availability. The three raspberry types have in common certain insect species as visitors, the most abundant being bumble bees (Bombus lapidarius, B. lucorum, B. terrestris, B. pratorum and B. pascuorum). Apis mellifera, Andrena species and hover flies. Bumble bees were responsible for about 60% of all visits, with honey bees, Andrena and hover flies making up most the remaining visits. Bombus species were more abundant through the particular observation days and through the different seasons, and they were present at almost all times of observations irrespective of climatic conditions in the studied area. The foraging behaviour and activity patterns, pollen loads and pollinating efficiency of the Bombus spp., Apis and Andrena spp. were analysed in relation to plant phenology, anthesis and dehiscence and to climatic variables. All bees had substantial pollen deposited on their bodies during visits, though few specifically collected it. Bombus species were found to strongly select young flowers, especially early in the morning when pollen was most abundant, while Apis and Andrena species visited unselectively. Bumble bees also foraged over substantially longer periods of the day, and in poorer weather, and they visited more flowers per minute than Apis and Andrena species. Bombus species also carried more pollen grains on their bodies than Apis and Andrena species, and deposited more pollen on raspberry stigmas; and because they foraged over longer range, they transferred pollen grains for longer distance than Apis mellifera. The flight directionality of Bombus, Apis and Andrena species among the flowers of Glen Moy and Glen Prosen was analysed. Pollen flow was also studied using fluorescent dyes, in field experiments during 1993 and 1994. Bombus and Apis transferred dye particles (pollen mimics) to different extents in different directions in the field. All the three visitors showed a strong tendency to move in the south-north direction (the direction of the raspberry rows); this would lead to increase in the gene flow within the same row in the presence of pollen carry-over. Pollen was carried up to 60m by Bombus species and 35m by honey bees. The work presented in this thesis provides evidence that (at least in Scotland) bumble bees are likely to be more important as pollinators of raspberries than other visitors. Reason why Bombus may be the preferred insect pollinators in wild and cultivated areas are discussed.

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Pascall, David John. "The diversity and distribution of multihost viruses in bumblebees." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/31597.

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The bumblebees (genus Bombus) are an ecologically and economically important group in decline. Their decline is driven by many factors, but parasites are believed to play a role. This thesis examines the factors that influence the diversity and distribution of multihost viruses in bumblebees using molecular and modelling techniques. In Chapter 2, I performed viral discovery to isolate new multihost viruses in bumblebees. I investigated factors that explain prevalence differences between different host species using co-phylogenetic models. I found that related hosts are infected with similar viral assemblages, related viruses infect similar host assemblages and related hosts are on average infected with related viruses. Chapter 3 investigated the ecology of four of the novel viruses in greater detail. I applied a multivariate probit regression to investigate the abiotic factors that may drive infection. I found that precipitation may have a positive or negative effect depending on the virus. Also, we observe a strong non-random association between two of the viruses. The novel viruses have considerably more diversity than the previously known viruses. Chapter 4 investigated the effect of pesticides on viral and non-viral infection. I exposed Bombus terrestris colonies to field realistic doses of the neoticotinoid pesticide clothianidin in the laboratory, to the mimic pulsed exposure of crop blooms. I found some evidence for a positive effect of uncertain size on the infection rate of pesticide exposed colonies relative to non-pesticide exposed colonies, a potentially important result. Chapter 5 explored the evolution of avirulent multihost digital organisms across fluctuating fitness landscapes within a discrete sequence space. Consistent with theory, I found that evolution across a fluctuating discrete landscape leads to a faster rate of adaptation, greater diversity and greater specialism or generalism, depending on the correlation between the landscapes. A large range of factors are found to be important in the distribution of infection and diversity of viruses, and we find evidence for abiotic, biotic and anthropogenic factors all playing a role.

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42

Cant, Elizabeth Tamzyn. "Do roads and hedges influence patterns of pollinator foraging movement and consequent plant gene flow in a UK agricultural landscape?" Thesis, University of Northampton, 2005. http://nectar.northampton.ac.uk/2999/.

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This thesis investigates the influence of hedges and roads (linear landscape features) on the patch-to-patch foraging movements of insect pollinators and consequent pollen- mediated gene flow in white clover, Trifolium repens. Experimental arrays were located within the lowland UK agricultural landscape incorporating a range of patch separation distances from 25m to 250m (using both artificial and natural linear features). Mark-re-sight, “residence” (the number of visits per foraging bout) and pollen transport observations were used to observe pollinator movement characteristics between experimental patches and re-parameterise an existing model of patch-to-patch gene flow. Levels and directions of plant gene flow were observed with phenotypic and isozyme markers, allowing validation of model predictions. Harmonic radar technology was used for the first time to track butterfly flight paths; data support the hypothesis of a 150 to 200m perceptual range, and non-random flight direction but limited association to wind direction, hedges, tracks or fence lines. Mark-re-sight observations indicated similar levels of patch visitation regardless of patch location, and trap-lining by Bombus spp. only between patches 50m or less apart. A single track road significantly enhanced gene flow between connected patches and was not a barrier to gene flow across it. In contrast, a hedge did not facilitate enhanced gene flow between connected patches and was a partial barrier where it occurred between patches. Model predictions of gene flow (1.3%, range 0.8 to 2.5%) agreed well with observed levels (ranging from 0.2 to 31.4%). It is proposed that pollinator movement observations alone could not provide an accurate means of estimating low level gene flow unless the variables of residence and pollen carryover were also considered. The possible influence of spatial and temporal variables including the role of hetero-specific forage on pollinator foraging movements and consequent plant gene flow from the local to landscape scale is also discussed

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Watts, Stella. "Plant-flower visitor interactions in the Sacred Valley of Peru." Thesis, University of Northampton, 2008. http://nectar.northampton.ac.uk/3000/.

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The structural organisation of species-rich plant-pollinator networks is important to understanding their ecology and evolution and is essential for making informed conservation and restoration decisions. This thesis reports on a study located at different altitudes in nine tributary valleys of the Sacred Valley, Vilcanota Highlands, Peru. The assemblages of flower visitors were described and the plant-flower visitor matrices were analysed and compared to those found from other montane systems. Additionally, the thesis also addressed how the European honeybee (Apis mellifera) fits into these communities. Previous studies have predicted that abundance, diversity, and importance of hymenopterans as pollinators decrease with increasing altitude, where they are replaced by Lepidoptera and Diptera. Contrary to other temperate montane areas, Hymenoptera were more diverse at higher elevations. Diptera was the most abundant functional group overall but did not significantly increase in abundance with altitude as predicted. Species richness of visited plants reached a maximum at the highest altitudes. Using ordination analysis, hummingbirds, honeybees, flies and beetles were identified as major functional groups of flower visitors with significantly different visitation profiles. Nestedness analysis revealed that the plant-flower visitor networks had a similar structure to other published networks, consisting of core groups of generalist plants and animals which interacted with one another and with specialised flower visitors and plants, respectively. The core species varied in identity between valleys, but were usually the species in greatest abundance, implying that the networks were abundance structured. In addition, 85% of the interactions were observed only in single valleys. This context specificity may have implications for the conservation of plant-pollinator interactions in the Sacred Valley. Comparisons of the pollinator efficiencies of honeybees, hummingbirds, native bees and moths to Duranta mandonii (Verbenaceae) demonstrated significant variation among flower visitors in rates of visitation, pollen removal ability and contribution to fruit set. This variation was not correlated: hummingbirds were by far the most frequent visitors but removed virtually no pollen and did not contribute to fruit set. Despite the taxonomic diversity of flower visitors, the main pollinators were large native bumblebees and honeybees. Results highlighted the importance of measuring efficiency components when documenting plant-pollinator interactions, and also demonstrated that visitation rates may give little insight into the relative importance of flower visitors. Overall, the study showed that Apis was the most generalist flower visitor and a dominant core species within networks. However, although Apis visited a relatively large proportion of the flora compared to native taxa, they only intensively utilised a small proportion of available plant species. No evidence was found from the surveys to suggest that honeybees used interference competition and displaced other species. It was suggested that because specialised rare species are frequently dependent on a core of generalist taxa honeybees may play an important role for the possibilities of rare species to persist. However, perhaps the greatest threat to biodiversity and the persistence of plant-flower visitor communities in the Sacred Valley is from the destruction and fragmentation of habitats and from facilitative interactions between native and alien plants, mediated through visitation from honeybees

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Jones, Emily Isobel. "Evolutionary Dynamics of Mutualism: The Role of Exploitation and Competition." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193583.

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Species exist in complex biotic environments, engaging in a variety of antagonistic and cooperative interactions. While these interactions are generally recognized to be context-dependent, varying in outcome in the presence of other interactions, studies tend to focus on each interaction in isolation. One of the main classes of species interaction is mutualism, in which partner species gain a net benefit from their interaction. However, mutualisms are beset by a variety of species that can reduce or even eliminate the benefits of mutualism through exploitation of and competition for the resources and services offered by mutualists. These exploiter species potentially threaten the ecological stability of mutualisms and may alter selection on mutualistic traits. Thus, understanding the ecology and evolution of mutualisms requires consideration of interactions with exploiter species. In this dissertation, I investigated the effects of exploiter species on mutualisms between plants and pollinators using a combination of eco-evolutionary modeling, optimization theory, and behavioral studies. Using two adaptive dynamics models of coevolution in exploited pollinating seed parasite mutualisms, I found that exploiters reduce mutualist densities and select for more parasitic mutualists. Nevertheless, the models demonstrate that intraspecific competition for host resources and host defense of those resources restrict the ecological conditions that lead to extinction of the mutualism, as well as the chances of evolution to extinction. Thus, exploiters are unlikely to be the threat to mutualisms that has been assumed previously. On the other hand, in another type of exploitation, exploitative predators may pose a greater threat to investment in mutualism than has been presumed. Through both optimal foraging theory and behavioral experiments on bumble bees, I found that the risk from ambush predators can change pollinator floral preferences when predators preferentially use high-quality flowers to locate their prey. This research suggests that predators of mutualists may have important top-down effects and that further research is needed to investigate the effects of exploitative predators on selection on mutualist traits.

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Hensel, Lisa E. "The Ecology and Evolution of Pollinator-mediated Interactions Among Spring Flowering Plants." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20186.

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Pollinator sharing in mixed species communities is expected to significantly contribute to mating patterns in contemporary populations but may also affect the evolutionary trajectory of traits associated with plant mating. In this thesis, I considered how the spring environment and pollinator sharing may contribute to the widespread convergence in traits among spring flowering species using comparative biology. The proposed correlation between a spring flowering phenology and white or light floral colour, fleshy fruits, woody growth forms and understory occupation is confirmed. In addition, I examined the effects of pollinator responses to community and population traits to determine the relative importance of inter- and intraspecific interactions in pollinator mediated reproductive success of a spring flowering species, Trillium grandiflorum. In this study, the reproductive success of T. grandiflorum was pollen limited. However, the magnitude of pollen limitation was influenced only by intraspecific density and varied independently of community diversity. The results of this thesis contribute significantly to our understanding of pollinator-mediated interactions in spring flowering communities but also highlight future avenues of investigation.

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Hamston, Tracey Jane. "Evolutionary relationships and reproductive ecology of endemic Sorbus species in south west UK : implications for conservation." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/26715.

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The genus Sorbus is an example of a taxonomically complex group (TCG) with diversity derived from hybridisation, polyploidy and apomixis. The focus of this study was to elucidate the evolutionary relationships among nine Sorbus species including endemics of the Devon and north Somerset region of the south west UK, determine main routes of polyploid formation and investigate reproductive sustainability in order to make recommendations for Sorbus conservation. Molecular analysis showed that genetic structure patterns and genotypic diversity support the hypothesis that the study polyploids are a product of rare interspecific hybridisation, of single origins and are maintained through apomictic reproduction. PCoA, Neighbour Joining analysis and parental simulations reveal a reticulated relationship, with diversification the result of hybridisations between sexual diploid Sorbus torminalis and both tetraploid and triploid species. Hybridisation between S. torminalis and tetraploid Sorbus margaretae (subgenus Aria) have likely given rise to the study members of subgenus Tormaria through production of a triploid which has subsequently backcrossed to Sorbus torminalis to form further tetraploids. The discovery of a cryptic hybrid in subgenus Aria also suggests occasional hybridisation events among tetraploids are a possible route for further tetraploid formation These events illustrate key routes of polyploid formation, both illustrating the role of triploids in tetraploid formation via the triploid bridge and the key role in sexual diploids in diversification in Sorbus. Hand pollination experiments showed that self-incompatibility in the triploid species (Sorbus subcuneata) means reliance on congeneric pollen from sympatric tetraploid species for seed production. Reproductive sustainability in this species is severely compromised through spatial isolation from compatible congeners. Our findings are strong support for the development of conservation strategies that aim to safeguard current diversity through actions that increase reproductive sustainability and recruitment opportunities, and promote opportunities for on-going hybridisation for future diversification of Sorbus in this region.

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Nicholson, Charles C. "No Farm Is An Island: Pollinators And Pollination In Agricultural Landscapes." ScholarWorks @ UVM, 2018. https://scholarworks.uvm.edu/graddis/985.

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Productive, resilient and sustainable agricultural systems are required to meet the immediate needs of a burgeoning human population, while avoiding ecosystem collapse. Agriculture provides food, fiber, fuels and other products for our current population of 7 billion and is still the major livelihood for 40% of people worldwide. By replacing natural habitat and employing chemical inputs, agriculture also negatively impacts biodiversity and impairs the provision of ecosystem services. This poses a challenge for agriculture as these impacted services are often those required for high yielding and high-quality crop production. Evidence is accumulating that agricultural management can safeguard biodiversity and ecosystem services while maintaining production, but critical questions remain concerning how management actions are shaped by broader landscape pattern and how these actions influence service-providing organisms across space and time. Through a combination of observational, experimental and modeling approaches, my dissertation examines relationships between management actions, landscape pattern and service-providing organisms using crop pollination by wild bees as a model system. First, I investigate how local management and landscape pattern interact to affect pollination services and the abundance and diversity of native bees in Vermont, USA. I then use two established models of pollinator foraging to investigate whether one popular intervention, enhancing floral resources, improves crop visitation, and whether pollinator traits and landscape pattern influence this effect. Next, I use a national data set of native bee diversity to test whether habitat enhancements increase taxonomic and functional diversity of native bee communities. Finally, I investigate whether resource continuity provided by consecutively blooming crops benefits wild bee communities. These four chapters contribute ecological knowledge of plant-animal interactions in anthropogenic landscapes. My findings also provide land managers with clear information about the effects of landscape conservation and farm management on crop pollinators.

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Gess, Sarah Kathleen. "Ecology and natural history of the Masarid wasps of the world with an assessment of their role as pollinators in southern Africa (Hymenoptera : Vespoidea : Masaridae)." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005354.

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The worldwide knowledge of the ecology and natural history of the masarid wasps, those wasps which bee-like provision their nest cells with pollen and nectar, is synthesized and discussed putting into context the investigations concerning nesting and flower visiting by southern African masarids conducted by the present author. Masarids are found mostly to favour warm to hot areas with relatively low rainfall and open scrubby vegetation. At the generic level the masarids of the Nearctic, Neotropical and Australian regions are distinct from each other and from those of the Palaearctic and Afrotropical regions combined. No species are shared between regions. Southern Africa is apparently the area of greatest species diversity. In this region, at least, there is a high incidence of narrow endemism. Masarids are associated with a relatively small range of plant families. Where sufficient records are available distinct major preferences are shown between zoogeographical regions. Relatedness of plant preferences between zoogeographical regions is apparent when relatedness of plant taxa is considered. Within a region there is marked overlap in masarid generic preferences for flower families. At the specific level there is marked oligolecty and narrow polylecty. The majority of nesting studies indicate that nest construction, egg laying and provisioning are performed by a single female per nest, however, nest sharing has been alledged for two species. No parasitic masarids have been recorded. Egg laying precedes provisioning. Mass provisioning is the rule. According to species, nests are sited in the ground, in non-friable soil or friable soil, in earthen vertical banks, on stones or on plants. Seven nest types are defined. Three bonding agents, water, nectar and self-generated silk are used. Masarids are evaluated as potential pollinators of their forage plants in southern Africa. The "masarid pollination syndrome", though less broad is shown to fall within that designated melittophily. The case studies considered make it clear that, whereas the masarids visiting some flower groups are members of a guild of potential pollinators, the masarids visiting others are probably their most important pollinators. Increasing land utilization is shown to threaten the existence of narrowly endmic masarid species.

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Ratnayake, R. M. C. S. "Phenology, pollination ecology and breeding systems of Polyalthia coffeoides, P. korinti and Xylopia championii (Annonaceae) in SriLanka." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31547308.

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Stokes, Richard L. "Pollination Ecology, Self-incompatibility and Genetic Diversity in the Herbaceous Eastern North American Spring Ephemeral, Erythronium americanum." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353089025.

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Dissertations / Theses on the topic 'Pollination ecology'

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