Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 12 of 12 for “"Pollen limitation"”.
-
Pollination systems in Namaqualand : a response to a predictable winter rainfall regime
… of empirical data supporting the notion of pollen limitation, necessitates further research in the pollination ecology of the region. In particular, research should concentrate on finding evidence for a reduction in fruit set resulting from pollen limitation. By furthering our knowledge in …
-
Consequences of plant population size for pollinator visitation and plant reproductive success
… for sexual reproduction. For each species, pollen limitation was present in all or nearly all populations, but the relationship between pollen limitation and population size was only present in Ononis masquillierii. However, in Echium plantagineum, significant relationships between both …
-
The birds, the bees and Erica: vulnerability of plant-pollinator communities in fragmented fynbos landscapes
… on plants' reproductive success (e.g. through pollen-limitation). Agriculture, timber plantations, invasion by alien trees and the urbanisation of the southern Cape lowlands have transformed and fragmented large parts of the former distribution range of many Erica species. Recent evidence …
-
The Relative Roles of Herbivore- and Pollinator-mediated Selection on the Evolution of Floral Display in the Invasive Plant, Lythrum salicaria
… pathway. Using a split-plot design, I measured pollen limitation and reproductive output in experimentally manipulated plants in the presence and absence of simulated herbivore damage in order to quantify the effects of damage and pollination on natural selection for floral display. My results …
-
Pollination Ecology, Self-incompatibility and Genetic Diversity in the Herbaceous Eastern North American Spring Ephemeral, Erythronium americanum
… and hand pollinations were performed to examine pollen limitation and self-incompatibility. Novel molecular markers were developed and used to quantify genetic diversity, clonal diversity, and population structure. Hand pollination treatments (natural, hand supplemented and bagged flowers) showed …
-
Moth pollination, low seed set, and vestigialization of attractive floral traits in Abronia umbellata (Nyctaginaceae)
… the day. We integrate this work with tests of pollen and resource limitation of seed production and with seed set surveys of natural populations to address proximate and ultimate causes of low seed set, finding low rates of pollinator visitation, high pollen limitation of seed production in all …
-
Evolution of floral and mating system variation in Camissoniopsis cheiranthifolia (Onagraceae): An evaluation of patterns and processes
… Increased selfing appeared to alleviate pollen limitation (PL) because it was associated with higher and less variable fruit set and reduced florivory by a microlepidopteran. However, evidence that florivores preferentially attacked larger flowers was equivocal. LF experienced stronger PL …
-
The evolution of self-compatibility and its genetic consequences in Leavenworthia alabamica (Brassicaceae)
… response to its innate transmission advantage or pollen limitation, and that this mating system may endanger the long-term viability of populations through mutation accumulation. The purpose of this dissertation was to evaluate the costs and benefits of self-fertilization in the species …
-
Molecular phylogenetics, systematics, reproductive safeguarding and chromosome evolution of the genus Lachenalia (Asparagaceae: Scilloideae)
… is employed here to test the hypothesis that pollen limitation, resulting from a low abundance of insect pollinators, promotes the evolution of reproductive safeguarding traits (self compatibility, autonomous selfing, bird pollination and clonal propagation) in low insect abundance contexts …
-
Ecology of stingless bees (Apidae, Meliponini) in lowland dipterocarp forests in Sabah, Malaysia, and an evaluation of logging impact on populations and communities
… that used a large range of plant species as pollen sources. Nevertheless, different species of bees had rather distinct pollen diets, a findind that was independent of fluctuations in flowering activity in the habitat. At one particular point in time colonies of one species (Trigona …
-
Understanding the role and impact of introduced honey bees in a submontane indigenous forest ecosystem
… sites. Weinmannia racemosa had lowest levels of pollen limitation at sites of high hive density. The combination of W. racemosa responses at the high hive density site suggest that small-flowered species, such as W. racemosa, have the potential to benefit from increased pollination success in …
-
Effects of temperature and pollinator availability on plant reproductive success in the Indiana spring ephemeral community
… community diversity on the extent of pollen limitation experienced by the perennial herb <em>C. virginica</em>, a relatively abundant member of the spring ephemeral community. The study was conducted over two consecutive years that had markedly different spring temperature patterns. I …