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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The structure and functioning of flower-visiting insect communities on hay meadows

Dicks, Lynn V. January 2002 (has links)
No description available.
2

Conservation ecology of Frithia humilis, an endangered succulent of sandstone outcrops in Mpumalanga, South Africa / Esmé Harris

Harris, Esmé January 2015 (has links)
Translocation involves the movement of organisms, by human intervention, from one area to other suitable (receptor) habitats. In a conservation context, translocation can be employed to support species preservation, population restoration and/or for ecological research. Despite decades of internationally published research, translocation remains a controversial endeavour. However, due to continual degradation and fragmentation of natural habitats in the face of human development, translocation is becoming a vital component of conservation efforts. Prior to the development of an Exxaro coal mine in Mpumalanga, a population of an endangered Highveld succulent species, Frithia humilis Burgoyne (Aizoaceae/Mesembryanthemaceae), was saved from extirpation by means of translocation. Three receptor habitats were identified within the distribution range of the species. The largest part of the donor population was transplanted to sandstone outcrops of the Ecca Group (Karoo Supergroup), resulting in four subpopulations residing on geological substrates typical of the species’ habitat. The remaining portion of the donor population was experimentally translocated to two habitats containing non-native geologies, namely sedimentary outcrops of the Wilge River Formation (Waterberg Group) and (igneous) felsite oucrops of the Rooiberg Group (Transvaal Supergroup). A control population was identified, occupying Ecca and Dwyka Group (Karoo Supergroup) sediments, as a measure to compare the response of translocated populations. A monitoring programme, utilising a plant age classification system, was initiated in February of 2010 to elucidate demographic trends and to gauge the response of translocated populations to novel environments. Plant survival, plant growth, flowering, fruiting (representing reproductive response) and seedling emergence were chosen as indicators to measure translocation success over the short term. Furthermore, quantitative and qualitative entomological investigations into the identity of possible F. humilis pollinators, as well as the presence of pollinator species at receptor habitats, were made. A repeatable methodology for post-translocation monitoring and scientifically sound baseline data for future comparative purposes were successfully established. Initial results showed that F. humilis subpopulations replanted on Ecca standstones had positive responses to translocation: Subpopulations survived and all but one increased in size. Individual plant growth increased, higher reproductive output was evident and seedling emergence was pervasive. Positive responses indicated that F. humilis populations translocated onto typical geologies had the potential to establish and persist over three years. Knowledge of this early success is of immense value to the conservation of the species, as a limited number of known natural populations remain. Coal mining, targeting coal seams underlying typical F. humilis habitats, is also likely to remain a threat. The viability of translocating F. humilis populations to non-typical geological substrates has shown limited efficacy. Poor survival along with inferior reproductive response confirmed Wilge River Formation outcrops as poor receptor sites for translocated F. humilis populations. Rooiberg felsite outcrops also proved to be dubious receptor sites, primarily since there was a downward trend in seedling emergence over time, suggesting inferior germination conditions. Nevertheless, translocation to non-native geological substrates did not have disastrous short-term consequences for these populations, since flowering, fruit production and seedling emergence continued, albeit at reduced (or continually declining) rates. Potential pollinator species of F. humilis were not revealed through quantitative surveys of insect diversity. Qualitative surveys proved more efficient and accurate at pinpointing insect pollinator species. This study provided the first evidence of Apidae, Megachilidae (Hymenoptera) and Bombyliidae (Diptera) insect species pollinating F. humilis. The generalist nature of the plant-pollinator relationship, as well as the presence of generalist pollinator species at some receptor habitats, probably contributed to the initial positive response of F. humilis flowering and fruiting after translocation. Results from this study, however promising, should be viewed as initial indications of translocation success. The literature review revealed a plethora of literature recommending post-translocation monitoring programmes for five years to several decades. This study confirmed that successful establishment of F. humilis can be determined after three years, but that long-term monitoring is required to evaluate persistence. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
3

Conservation ecology of Frithia humilis, an endangered succulent of sandstone outcrops in Mpumalanga, South Africa / Esmé Harris

Harris, Esmé January 2015 (has links)
Translocation involves the movement of organisms, by human intervention, from one area to other suitable (receptor) habitats. In a conservation context, translocation can be employed to support species preservation, population restoration and/or for ecological research. Despite decades of internationally published research, translocation remains a controversial endeavour. However, due to continual degradation and fragmentation of natural habitats in the face of human development, translocation is becoming a vital component of conservation efforts. Prior to the development of an Exxaro coal mine in Mpumalanga, a population of an endangered Highveld succulent species, Frithia humilis Burgoyne (Aizoaceae/Mesembryanthemaceae), was saved from extirpation by means of translocation. Three receptor habitats were identified within the distribution range of the species. The largest part of the donor population was transplanted to sandstone outcrops of the Ecca Group (Karoo Supergroup), resulting in four subpopulations residing on geological substrates typical of the species’ habitat. The remaining portion of the donor population was experimentally translocated to two habitats containing non-native geologies, namely sedimentary outcrops of the Wilge River Formation (Waterberg Group) and (igneous) felsite oucrops of the Rooiberg Group (Transvaal Supergroup). A control population was identified, occupying Ecca and Dwyka Group (Karoo Supergroup) sediments, as a measure to compare the response of translocated populations. A monitoring programme, utilising a plant age classification system, was initiated in February of 2010 to elucidate demographic trends and to gauge the response of translocated populations to novel environments. Plant survival, plant growth, flowering, fruiting (representing reproductive response) and seedling emergence were chosen as indicators to measure translocation success over the short term. Furthermore, quantitative and qualitative entomological investigations into the identity of possible F. humilis pollinators, as well as the presence of pollinator species at receptor habitats, were made. A repeatable methodology for post-translocation monitoring and scientifically sound baseline data for future comparative purposes were successfully established. Initial results showed that F. humilis subpopulations replanted on Ecca standstones had positive responses to translocation: Subpopulations survived and all but one increased in size. Individual plant growth increased, higher reproductive output was evident and seedling emergence was pervasive. Positive responses indicated that F. humilis populations translocated onto typical geologies had the potential to establish and persist over three years. Knowledge of this early success is of immense value to the conservation of the species, as a limited number of known natural populations remain. Coal mining, targeting coal seams underlying typical F. humilis habitats, is also likely to remain a threat. The viability of translocating F. humilis populations to non-typical geological substrates has shown limited efficacy. Poor survival along with inferior reproductive response confirmed Wilge River Formation outcrops as poor receptor sites for translocated F. humilis populations. Rooiberg felsite outcrops also proved to be dubious receptor sites, primarily since there was a downward trend in seedling emergence over time, suggesting inferior germination conditions. Nevertheless, translocation to non-native geological substrates did not have disastrous short-term consequences for these populations, since flowering, fruit production and seedling emergence continued, albeit at reduced (or continually declining) rates. Potential pollinator species of F. humilis were not revealed through quantitative surveys of insect diversity. Qualitative surveys proved more efficient and accurate at pinpointing insect pollinator species. This study provided the first evidence of Apidae, Megachilidae (Hymenoptera) and Bombyliidae (Diptera) insect species pollinating F. humilis. The generalist nature of the plant-pollinator relationship, as well as the presence of generalist pollinator species at some receptor habitats, probably contributed to the initial positive response of F. humilis flowering and fruiting after translocation. Results from this study, however promising, should be viewed as initial indications of translocation success. The literature review revealed a plethora of literature recommending post-translocation monitoring programmes for five years to several decades. This study confirmed that successful establishment of F. humilis can be determined after three years, but that long-term monitoring is required to evaluate persistence. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
4

POLLINATION ECOLOGY OF PEDICULARIS SCEPTRUM-CAROLINUM : An investigation on flower visits in northern Sweden / Pollinationsekologi för Kung Karls spira : En undersökning av blombesök i norra Sverige

Närvä, Johan January 2022 (has links)
Pedicularis sceptrum-carolinum is threatened in much of its geographic range. As it reproduces vegetatively only to a limited extent, the species relies heavily on pollinators for reproduction. One aspect often overlooked in restoration efforts is the pollination ecology of flowering plants and their pollinators. To get a better understanding of the pollination ecology of P. sceptrum-carolinum in northern Sweden, their flower visitors were identified, and the number of flower visits was counted for flowering individuals at three different sites. The nearby flowering plant community was inventoried around each investigated P. sceptrum-carolinum. It was tested whether the number of flower visits were similar among sites, between large and small populations, and between populations with a majority of fresh flowers and populations with a majority of senescent flowers. To investigate whether the nearby plant community is important for the pollination of the species, the correlation between flower visits of P. sceptrum-carolinum and nearby flower abundance and diversity was analysed. No difference was found between sites, between large and small populations, or between populations where the majority of flowers were fresh and populations with a majority of flowers which had senesced. A moderate positive correlation was found between number of flower visits and nearby flower abundance and diversity respectively, if one site with an exceptionally large abundance of Trifolium pratense was excluded. As abundance and diversity of the nearby flowering plants were themselves highly correlated, their individual effect on flower visits of the studied P. sceptrum-carolinum could not be told apart in this study.
5

Assessment of the condition and relationships of the western honey bee, Apis mellifera mellifera, in northern Sweden

Valeria, Ciurcina January 2021 (has links)
Honey bees play an important role in pollination ecology but the conditions of health and genetic purity in North Sweden are not very clear because most honey bees are not native to boreal environments. Emerging studies on insect microbiomes are focusing on the role of lactobacillus as a health factor, given its connection with nectar digestion processes. The aim of this thesis is an assessment of the genetic purity of the western honey bee (Apis mellifera mellifera) and the understanding of implications between non-pathogenic microorganisms and the honey bee's health status. Additionally, the relationships between hive’s colony size, environment, and health status are tested to understand any possible linkages, following the idea that different environments might affect the quantity of lactobacillus and thus immunity and resistance patterns in honey bees. For this project, 15 beehives were sampled in the region of Västerbotten in the summer of 2019/2020, in different types of habitats, with different purposes: analyzing the genetic purity with the wing morphometry method, cultivating the microorganisms that are present in the guts of bees, and comparing the results between urban and agricultural environments. The wing morphometry genetic assessment results showed that up to 80% of the bee keepers who took part in this study breed the subspecies A. mellifera mellifera with no significant level of hybridization with other subspecies. Therefore, honey bee purity status depends on the beekeeper’s choices. Microscopy and the analysis of the microbiomes showed the presence of lactobacillus and minor microorganisms. Cultivable lactic acid bacteria are more present in healthy honey bees in locations with higher plant biodiversity. In fact, the bacillus microbiomes are present in both agricultural and semi-urban areas but are more abundant and diverse in long-lived honey bees from hives in semi-urban area. This could depend on the higher plant diversity in these sites. Finally, the purity of subspecies does not influence adaptive responses or resistance in boreal environments.
6

Bees By The Interstate: The effectiveness of interchange greenspace restoration for bee conservation

McMahon, Kiersten 09 January 2023 (has links)
No description available.
7

Polinační ekologie \kur{Impatiens sakeriana} / Pollinatieon biology of \kur{Impatiens sakeriana}

PATÁČOVÁ, Eliška January 2011 (has links)
The pollination biology of Impatiens sakeriana was studied in Northwest province, Cameroon. The most efficient way of reproduction was examined, futhermore nectar production was neasured and bird pollinators was observed.
8

Floral Color Properties of Serpentine Seep Assemblages Depend on Community Size and Species Richness

LeCroy, Kathryn A., Arceo-Gómez, Gerardo, Koski, Matthew H., Morehouse, Nathan I., Ashman, Tia L. 08 January 2021 (has links)
Functional traits, particularly those that impact fitness, can shape the ecological and evolutionary relationships among coexisting species of the same trophic level. Thus, examining these traits and properties of their distributions (underdispersion, overdispersion) within communities can provide insights into key ecological interactions (e.g., competition, facilitation) involved in community assembly. For instance, the distribution of floral colors in a community may reflect pollinator-mediated interactions between sympatric plant species, and the phylogenetic distribution of color can inform how evolutionary contingencies can continue to shape extant community assemblages. Additionally, the abundance and species richness of the local habitat may influence the type or strength of ecological interactions among co-occurring species. To evaluate the impact of community size and species richness on mechanisms shaping the distribution of ecologically relevant traits, we examined how floral color (defined by pollinator color vision models) is distributed within co-flowering assemblages. We modeled floral reflectance spectra of 55 co-flowering species using honeybee (Apis mellifera) and syrphid fly (Eristalis tenax) visual systems to assess the distributions of flower color across 14 serpentine seep communities in California. We found that phylogenetic relatedness had little impact on the observed color assemblages. However, smaller seep communities with lower species richness were more overdispersed for flower color than larger, more species-rich communities. Results support that competitive exclusion could be a dominant process shaping the species richness of flower color in smaller-sized communities with lower species richness, but this is less detectable or overwhelmed by other processes at larger, more speciose communities.
9

Pollination Ecology, Self-incompatibility and Genetic Diversity in the Herbaceous Eastern North American Spring Ephemeral, Erythronium americanum

Stokes, Richard L. January 2012 (has links)
No description available.
10

Pollination Ecology and Demography of a Deceptive Orchid

Walsh, Ryan Patrick 07 August 2013 (has links)
No description available.

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