Thesis (M.Sc.)--York University, 2004. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 89-91). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11892

Thesis (M. Sc.)--York University, 2001. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 45-54, 144-151). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ66387.

Augochlorini (Halictinae) e um elemento comum na região Neotropical, e a historia natural das suas espécies e marcada pela plasticidade quando comparada a outras abelhas. A tribo e grupo-irmão de Halictini, e seus fosseis datam pelos menos do âmbar Dominicano (cerca de 20 milhões de anos). As relações entre os gêneros de Augochlorini foram reconstruídas de maneira insatisfatoria, sendo as hipóteses existentes em parte incongruentes, pouco robustas e baseadas apenas em dados morfológicos. Neste sentido, o presente estudo apresenta uma abordagem filogenética empregando dados moleculares. Para 76 terminais, foram obtidas sequências de DNA de quatro genes, 28S, Fator de Alongamento 1-alfa, Rodopsina Verde e wingless, somando 3043 pares de bases alinhadas. Análises de máxima parcimônia, máxima verossimilhança e inferência bayesiana foram conduzidas para os dados moleculares em conjunto, incluindo ou não regiões de alinhamento ambíguo (alças e íntrons). Os resultados, em consenso, apontam para a parafilia das duas subtribos de Augochlorini sensu Engel, com três grupos de gêneros, gr. Corynura, gr. Rhinocorynura e gr. Chlerogella formando uma politomia na base. Os demais gêneros formam um agrupamento que e dividido em três grandes clados, cujas relações não foram bem resolvidas. O primeiro e composto pelo grupo Megaloptidia e os gêneros Augochloropsis, Augochlorodes e Pseudaugochlora, o segundo pelo grupo Neocorynura mais Chlerogas, Paroxystoglossa e Temnosoma, e o terceiro pelo grupo Augochlora e Caenaugochlora, Megalopta e Thectochlora. As primeiras linhagens de Augochlorini se diversificaram entre 7060 milhões de anos atrás, sendo que desde 50 milhões de anos vem ocorrendo uma gradativa diversificação do grupo. A re-análise da morfologia externa do grupo não foi útil para entender melhor a evolução do grupo que em trabalhos anteriores, inclusive diminuindo o poder explicativo da hipótese gerada pela evidencia total. As hipóteses moleculares apresentaram novas evidencias que guiam futuros estudos para o grupo, para que se possa entender a evolução dentro de cada um dos seus clados. / Augochlorini (Halictinae) is a common element in the Neotropical region, and his natural history is known by their relatively plasticity when compared to other bees. Augochlorini is sister-group of Halictini, and its oldest fossils date from the Dominican amber (about 20 million years before present). The phylogenetic relationships among their genera were only superficially reconstructed, the competing hypothesis are not entirely congruent nor robust and were based only on morphological data. With this background, this study aims to present a molecular phylogeny to Augochlorini. It was obtained, for 76 terminals, DNA sequences of four genes, 28S, Elongation Factor 1-alpha, Green Rodopsin and Wingless, giving a 3043 base pair alignment. Maximum parsimony, maximum likelihood and Bayesian inference analyses were carried out for the molecular data, including or excluding regions of ambiguous alignment (loops and introns). The results, based on consensus trees, suggest the paraphyly of both Augochlorini subtribes (sensu Engel), with three groups of genera, gr. Corynura, gr. Rhinocorynura e gr. Chlerogella forming a basal polytomy with a clade containing the remaining genera. This clade has three subgroups, whose phylogenetic relationships were not well stabilized. The first group consists of gr. Megaloptidia and Augochloropsis, Augochlorodes, and Pseudaugochlora, the second group of gr. Neocorynura plus Chlerogas, Paroxystoglossa, and Temnosoma, and the third group consists of gr. Augochlora and Caenaugochlora, Megalopta, and Thectochlora. The first Augochlorini lineages diversified by 70 to 60 million years ago, and since 50 mya there has been a gradual diversification of the group. The reanalysis of augochlorines external morphology was not helpful for understanding the evolution of the group, and also reduced the explanatory power of the total evidence hypothesis. The molecular hypothesis brought new evidences to guide future studies for the group, and positively favored the conception about the evolution of Augochlorini main clades.

Augochlorini (Halictinae) e um elemento comum na região Neotropical, e a historia natural das suas espécies e marcada pela plasticidade quando comparada a outras abelhas. A tribo e grupo-irmão de Halictini, e seus fosseis datam pelos menos do âmbar Dominicano (cerca de 20 milhões de anos). As relações entre os gêneros de Augochlorini foram reconstruídas de maneira insatisfatoria, sendo as hipóteses existentes em parte incongruentes, pouco robustas e baseadas apenas em dados morfológicos. Neste sentido, o presente estudo apresenta uma abordagem filogenética empregando dados moleculares. Para 76 terminais, foram obtidas sequências de DNA de quatro genes, 28S, Fator de Alongamento 1-alfa, Rodopsina Verde e wingless, somando 3043 pares de bases alinhadas. Análises de máxima parcimônia, máxima verossimilhança e inferência bayesiana foram conduzidas para os dados moleculares em conjunto, incluindo ou não regiões de alinhamento ambíguo (alças e íntrons). Os resultados, em consenso, apontam para a parafilia das duas subtribos de Augochlorini sensu Engel, com três grupos de gêneros, gr. Corynura, gr. Rhinocorynura e gr. Chlerogella formando uma politomia na base. Os demais gêneros formam um agrupamento que e dividido em três grandes clados, cujas relações não foram bem resolvidas. O primeiro e composto pelo grupo Megaloptidia e os gêneros Augochloropsis, Augochlorodes e Pseudaugochlora, o segundo pelo grupo Neocorynura mais Chlerogas, Paroxystoglossa e Temnosoma, e o terceiro pelo grupo Augochlora e Caenaugochlora, Megalopta e Thectochlora. As primeiras linhagens de Augochlorini se diversificaram entre 7060 milhões de anos atrás, sendo que desde 50 milhões de anos vem ocorrendo uma gradativa diversificação do grupo. A re-análise da morfologia externa do grupo não foi útil para entender melhor a evolução do grupo que em trabalhos anteriores, inclusive diminuindo o poder explicativo da hipótese gerada pela evidencia total. As hipóteses moleculares apresentaram novas evidencias que guiam futuros estudos para o grupo, para que se possa entender a evolução dentro de cada um dos seus clados. / Augochlorini (Halictinae) is a common element in the Neotropical region, and his natural history is known by their relatively plasticity when compared to other bees. Augochlorini is sister-group of Halictini, and its oldest fossils date from the Dominican amber (about 20 million years before present). The phylogenetic relationships among their genera were only superficially reconstructed, the competing hypothesis are not entirely congruent nor robust and were based only on morphological data. With this background, this study aims to present a molecular phylogeny to Augochlorini. It was obtained, for 76 terminals, DNA sequences of four genes, 28S, Elongation Factor 1-alpha, Green Rodopsin and Wingless, giving a 3043 base pair alignment. Maximum parsimony, maximum likelihood and Bayesian inference analyses were carried out for the molecular data, including or excluding regions of ambiguous alignment (loops and introns). The results, based on consensus trees, suggest the paraphyly of both Augochlorini subtribes (sensu Engel), with three groups of genera, gr. Corynura, gr. Rhinocorynura e gr. Chlerogella forming a basal polytomy with a clade containing the remaining genera. This clade has three subgroups, whose phylogenetic relationships were not well stabilized. The first group consists of gr. Megaloptidia and Augochloropsis, Augochlorodes, and Pseudaugochlora, the second group of gr. Neocorynura plus Chlerogas, Paroxystoglossa, and Temnosoma, and the third group consists of gr. Augochlora and Caenaugochlora, Megalopta, and Thectochlora. The first Augochlorini lineages diversified by 70 to 60 million years ago, and since 50 mya there has been a gradual diversification of the group. The reanalysis of augochlorines external morphology was not helpful for understanding the evolution of the group, and also reduced the explanatory power of the total evidence hypothesis. The molecular hypothesis brought new evidences to guide future studies for the group, and positively favored the conception about the evolution of Augochlorini main clades.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 65-72).

Aggregations of the ground-nesting bee Halictus rubicundus were found at several locations across the UK. The phenology, social organisation, nest architecture and foraging behaviour of this bee were described for the largest of these aggregations (Invergowrie, Scotland). This site was unusual in having an extremely high brood mortality due to the impact of an anthomyiid fly. Nest parasitism was found to be directly density-dependent and it lead to a marked decline in nest numbers over the period of this study, indicating the possible forthcoming extinction of the aggregation. The other sites contained smaller nesting aggregations and the level of parasitism was considerably less. There was a marked variation in size across UK populations and this was explained by a temperature rather than a latitudinal cline. There was no evidence from field or laboratory studies to suggest that this species is endothermic; H. rubicundus is purely a behavioural thermoregulator. The effect of size upon various rates of heat exchange were examined in the laboratory for both sexes, and related to behaviours observed at the nest-site. Thus the microclimatic windows for different activities were established. The abundance of flying individuals at the nest-site was highly predictable from ambient temperature and light intensity; with predictions during a single day being more accurate than those combining several days throughout the season. Furthermore the usefulness of standard operative temperatures in predicting flight activity was assessed. The thoracic temperature of both sexes depended on the prevailing ambient temperature and also on the size of the individual while either basking or flying. Body temperatures increased with both ambient temperature and head width. However when both these predictors were combined into a single model, then size was only a strong predictor at lower temperatures. These findings were used to explain many of the behavioural patterns observed at Invergowrie. The nest site selection behaviour of females was examined both within and across sites. H. rubicundus was able to utilise a range of edaphic and microclimatic conditions when choosing a site to excavate a nest. There were some factors with broad tolerances such as slope and hardness, and others with much narrower limits such as aspect, soil humidity and particle composition. The thermal advantages of having a warm nest meant that the most suitable areas were those with a southern aspect and a slope which maximised the absorption of solar radiation. Limited areas of substrate with the most desirable characteristics resulted in gregarious nesting ('limited substrate' hypothesis). There was a preference for softer soils, that were easier to dig, within a site with a low overall density; but in much denser aggregations problems of maintaining the structural integrity of a nest lead to the favouring of harder soils. The tendency to nest in close proximity to the natal nest (philopatry) complemented the 'limited substrate' hypothesis in producing an aggregation of nests. The spatial distributions of nests within aggregations were examined using nearest neighbour distance analyses; at low densities, microscale variation in substrate quality produced clumped patterns, whereas at high densities the risk of adjacent nests collapsing into one another forced nest spacing to be more regular. Findings concerning temperature dependence of nesting and foraging activities, and broader environmental controls on nest-site selection, are considered in relation to key aspects of bee biology: the origins and function of social behaviours, the conservation of, or provision of, nest-sites, and the utility of solitary bees as crop pollinators.

Bees provide vital ecosystem services for cropping systems as well as natural landscapes. Declines in both both native bee and managed honey bee (Apis mellifera L.) populations has brought attention to the significance of their role as pollinators in managed and native ecosystems. As a result, conservation efforts have been undertaken to preserve them. While considerable attention has been given to honey bees, relatively little is known about many native bee species. Of particular interest is the family Halictidae, which can comprise the majority of observed individuals in many habitats. These, often small, bees are difficult to identify, and, as a result, relatively little is known about their preferred floral hosts. Because bee species assemblages vary significantly from region to region, it is important to have an understanding of local populations and their floral hosts. It is also important to understand factors which affect the quantity and quality of floral resources, such as anthropogenic disturbance. The Pacific Northwest is a diverse landscape, with rich agricultural and wildland environments that require pollinators in order to continue to thrive. Two studies examine the interface between these two systems, the first explores how roadside disturbance, which is prevalent across the world, impacts native pollinators across habitat types, and the second explores the diet of common native species, and how that diet changes across habitat types. In these studies, it was found that roadside disturbance was associated with reduced native bee diversity and abundance in the seasonally wet Willamette Valley of Oregon, but not in the more xeric Central Oregon. Bee abundance was positively correlated with temperature. Bee diet was more diverse in areas of scarce floral resources. In both regions, exotic plants were important floral hosts, representing nearly half of observed floral visitations. This thesis presents results of species analysis, floral richness and density correlations, and comparisons of floral resources used by different bee species. Implications and recommendations for land management are discussed. / Graduation date: 2013

Pollination syndromes refer to stereotyped floral characteristics (flower colour, shape, etc.) that are associated with a functional group of pollinators (bee, bird, etc.). The trumpet creeper Campsis radicans, endemic to the southeast and mid-west United States, has been assigned to the hummingbird-pollination syndrome, due mainly to its red, trumpet-shaped flowers. Previous studies demonstrated that the ruby-throated hummingbird Archilochus colubris is C. radicans' primary pollinator, but anecdotal data suggest various bee species may provide pollination service when hummingbirds are absent. This study characterised C. radicans nectar volume and concentration by time of day. Nectar volume was suitable for hummingbirds, but concentration was higher than typical hummingbird-pollinated plants (∼20% w/w); at ∼30% w/w, it approached the concentration expected in bee-pollinated plants (∼50% w/w). We also found substantial amounts of nectar at night. Two C. radicans populations received virtually no hummingbird visits, but the number of bees were markedly higher than in the populations previously described. Interestingly, there were no night-time visitors despite the large quantity of nocturnal nectar. Based on previously published pollen delivery per visit by various species, this study estimated that cumulative deposition by bees routinely reached pollen deposition thresholds for setting fruit in C. radicans. They are, unequivocally, the predominant pollinators in these populations, thus providing pollination service in the absence of hummingbirds. These results highlight C. radicans as a food source for native bees and add to the understanding of how floral phenotypes can facilitate pollination by disparate functional groups.

This project examined multiple aspects of the reproductive biology of the wetland invasive species, purple loosestrife (<i>Lythrum salicaria</i> L.), in central Saskatchewan. An examination of insect taxa visiting the three floral morphs of <i>Tristylous</i> L. <i>salicaria</i>, as well as a ranking of the pollination efficiency of individual insect species, an apparent first for L salicaria, was undertaken. Surface features of the floral nectary of L. <i>salicaria</i>, as well as floral nectar secretion dynamics, were also investigated. This project also re-visited some of the previous work done on this invasive species, including various floral organ morphometrics in relation to heterostyly, and aspects of the tristylous breeding system including self-fertilization, and fertilization potential of both illegitimate pollination and legitimate pollination.<p>The trimorphic nature of the sexual floral organs of L. <i>salicaria</i> were well defined in Saskatchewan. Significant differences in length (long-, intermediate- and short-style lengths) exist between all three floral morphs. Lengths of the staminal filaments (long, intermediate, and short) were also significantly different. Also the floral nectary in L. <i>salicaria</i> is located in a depression formed at the interface of the hypanthium and the gynoecium. Several stomata are located at regular intervals along the nectary surface, and may constitute the escape route for floral nectar. No morphological differences in nectary structure were apparent among the three floral morphs.<p>Nectar secretion dynamics of L. <i>salicaria</i> were examined between the three floral morphs throughout two summer days in 2006. Peak average nectar volumes and nectar sugar quantities were detected at 3:00 pm, and, interestingly, no significant differences were detected between floral morphs, in accordance with nectary morphology. The estimated secretion rates for L. <i>salicaria</i> ranged from 61 83 µg of nectar sugar per flower per hour.<p>Hand-pollination experiments carried out over the summers of 2006 and 2007 at three field sites in and around Saskatoon have verified the strong self-incompatibility in the breeding system of this tristylous species. Intramorph pollination, using illegitimate pollen, did not result in fertilisation, whereas legitimate hand-pollination experiments yielded multiple pollen tubes at the style base, without exception.<p><i>Lythrum salicaria</i> in central Saskatchewan was visited by several bee taxa including honeybees (<i>Apis mellifera</i> L.), bumblebees (Bombus spp.), leafcutter bees (Megachile spp.), and sweat bees (Lasioglossum spp.). A single visit by <i>Anthophora furcata</i> (Panzer) was also recorded in 2007. Generally, bee visits led to high levels of pollination success as determined by fluorescence microscopy of pollen tubes following single insect visits to previously-unvisited flowers. However, most visits by hoverflies (Syrphidae) were non-pollinating. Visits by Pieris rapae (L.), yellowjacket wasps (Vespidae) and some non-syrphid flies (Diptera) also yielded no pollen tubes at the style base.<p>A study of the ultrastructure and development of the floral nectary of the purple loosestrife cultivar Morden Gleam (<i>Lythrum virgatum</i> L. x L. alatum Pursh.) showed that starch build up in pre-secretory nectary tissues declined throughout secretion, and is virtually absent in post-secretory nectary tissues. The lack of a direct vascular supply to the floral nectary suggests that the starch breakdown products likely make up most of the floral nectar carbohydrates. Surface features of the floral nectary in Morden Gleam closely resembled those of L. salicaria, located in the valley formed between the hypanthium and gynoecium. Nectary stomata, occasionally in pairs, likely serve as outlets for nectar in this cultivar.

This project examined multiple aspects of the reproductive biology of the wetland invasive species, purple loosestrife (<i>Lythrum salicaria</i> L.), in central Saskatchewan. An examination of insect taxa visiting the three floral morphs of <i>Tristylous</i> L. <i>salicaria</i>, as well as a ranking of the pollination efficiency of individual insect species, an apparent first for L salicaria, was undertaken. Surface features of the floral nectary of L. <i>salicaria</i>, as well as floral nectar secretion dynamics, were also investigated. This project also re-visited some of the previous work done on this invasive species, including various floral organ morphometrics in relation to heterostyly, and aspects of the tristylous breeding system including self-fertilization, and fertilization potential of both illegitimate pollination and legitimate pollination.<p>The trimorphic nature of the sexual floral organs of L. <i>salicaria</i> were well defined in Saskatchewan. Significant differences in length (long-, intermediate- and short-style lengths) exist between all three floral morphs. Lengths of the staminal filaments (long, intermediate, and short) were also significantly different. Also the floral nectary in L. <i>salicaria</i> is located in a depression formed at the interface of the hypanthium and the gynoecium. Several stomata are located at regular intervals along the nectary surface, and may constitute the escape route for floral nectar. No morphological differences in nectary structure were apparent among the three floral morphs.<p>Nectar secretion dynamics of L. <i>salicaria</i> were examined between the three floral morphs throughout two summer days in 2006. Peak average nectar volumes and nectar sugar quantities were detected at 3:00 pm, and, interestingly, no significant differences were detected between floral morphs, in accordance with nectary morphology. The estimated secretion rates for L. <i>salicaria</i> ranged from 61 83 µg of nectar sugar per flower per hour.<p>Hand-pollination experiments carried out over the summers of 2006 and 2007 at three field sites in and around Saskatoon have verified the strong self-incompatibility in the breeding system of this tristylous species. Intramorph pollination, using illegitimate pollen, did not result in fertilisation, whereas legitimate hand-pollination experiments yielded multiple pollen tubes at the style base, without exception.<p><i>Lythrum salicaria</i> in central Saskatchewan was visited by several bee taxa including honeybees (<i>Apis mellifera</i> L.), bumblebees (Bombus spp.), leafcutter bees (Megachile spp.), and sweat bees (Lasioglossum spp.). A single visit by <i>Anthophora furcata</i> (Panzer) was also recorded in 2007. Generally, bee visits led to high levels of pollination success as determined by fluorescence microscopy of pollen tubes following single insect visits to previously-unvisited flowers. However, most visits by hoverflies (Syrphidae) were non-pollinating. Visits by Pieris rapae (L.), yellowjacket wasps (Vespidae) and some non-syrphid flies (Diptera) also yielded no pollen tubes at the style base.<p>A study of the ultrastructure and development of the floral nectary of the purple loosestrife cultivar Morden Gleam (<i>Lythrum virgatum</i> L. x L. alatum Pursh.) showed that starch build up in pre-secretory nectary tissues declined throughout secretion, and is virtually absent in post-secretory nectary tissues. The lack of a direct vascular supply to the floral nectary suggests that the starch breakdown products likely make up most of the floral nectar carbohydrates. Surface features of the floral nectary in Morden Gleam closely resembled those of L. salicaria, located in the valley formed between the hypanthium and gynoecium. Nectary stomata, occasionally in pairs, likely serve as outlets for nectar in this cultivar.