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.

Floral traits are typically associated with specific groups of pollinators. Yet, many flowering plants are pollinated by more than one group of pollinators. To explore the influence of multiple effective pollinators on floral traits, I examined how the pollinator assemblage of Polemonium brandegeei affects pollen movement and selection on floral traits. I documented phenotypic and genetic variation in floral traits, and quantified the effectiveness of floral visitors. In natural populations, I quantified pollen removal and deposition over two consecutive flowering seasons. I then performed a pair of novel array experiments to estimate selection through female (seeds set) and male (seeds sired) function on floral traits by two important pollinators, hawkmoths and hummingbirds. My analysis of field populations demonstrated that height and relative positioning of sex organs were important for the removal and deposition of pollen. Individuals of P. brandegeei displayed a large degree of continuous and heritable variation, particularly in the relative positioning of sex organs. Plants in the same population displayed stigmas recessed below (reverse herkogamy), or exserted above anthers (approach herkogamy). My array experiments determined that variation in herkogamy is likely maintained through contrasting selection, because hawkmoths selected for recessed stigmas but hummingbirds selected for exserted stigmas. While my results were the first to detect selection for reverse herkogamy by hawkmoths, I also identified selection for traits that are typically associated with both pollinators. For example, hawkmoths selected for narrow corolla tubes, and hummingbirds selected for longer corolla tubes. The selection I detected on floral traits through female function was generally stronger than through male function, which runs counter to traditional theory of gender-biased selection. My findings indicate that floral traits can conform to intermediate dimensions between the optima of two pollinators (herkogamy), or appear specialized to one pollinator (tube length). Therefore, cumulative arrangements of floral traits (floral design) can effectively function under pollination by two pollinators that exert different selection pressures on traits.

I investigated how orchid biology, floral morphology, and diversity of surrounding floral and pollinator communities affected reproductive success and hybridization of Cypripedium candidum and C. parviflorum. Floral dimensions, including pollinator exit routes were smallest in C. candidum, largest in C. parviflorum, with hybrids intermediate and overlapping with both. This pattern was mirrored in the number of insect visitors, fruit set, and seed set. Exit route size seemed to restrict potential pollinators to a subset of visiting insects, which is consistent with reports from other rewardless orchids. Overlap among orchid taxa in morphology, pollinators, flowering phenology, and spatial distribution, may affect the frequency and direction of pollen transfer and hybridization. The composition and abundance of co-flowering rewarding plants seems to be important for maintaining pollinators in orchid populations. Comparisons with orchid fruit set indicated that individual co-flowering species may be facilitators or competitors for pollinator attention, affecting orchid reproductive success.

The pollination drop is a conservative pollination mechanism observed in all major gymnosperm taxa. Despite its ubiquity and essentiality to gymnosperm reproductive success, it remains poorly understood. Recent studies identifying conifer ovular secretion proteins have indicated a more complex role for ovular secretions than pollen receipt. We used a proteomics approach to analyze the pollination drops of four gymnosperm species (Juniperus communis (common juniper), Juniperus oxycedrus (prickly juniper), Chamaecyparis lawsoniana (Port Orford cedar), and Welwitschia mirabilis). Pollination drop proteins were separated by SDS-PAGE, and the most abundant proteins were analyzed by mass spectrometry and sequenced. Based on BLAST searching of combined amino acid sequences, several proteins were identified: an 83 kDa subtilisin-like proteinase, a 62 kDa glycosyl hydrolase, a 47.5 kDa glucan 1,3-ß-glucosidase precursor, a 30 kDa chitinase, and a 25 kDa thaumatin-like protein in J. connnunis; a 30 kDa chitinase, a 25 kDa thaumatin-like protein, and a 32.5 kDa glucanase-like protein in J. oxycedrus; an 83 kDa subtilisin-like proteinase, a 62 kDa (ß-D-glucan exohydrolase, a 47.5 kDa glucan 1,3-ß-glucosidase, and two 25 kDa thaumatin-like proteins in C. lawsoniana, and a 25 kDa chitinase in W. mirabilis. Gymnosperm phylogeny is a highly debated topic, particularly following the widespread adoption of molecular phylogenetic analyses which conflict with historical morphological phylogenies. The gymnosperms are a difficult group to classify because of their deep evolutionary history and lack of conservative features. Considering that the pollination drop is a highly conservative feature of gymnosperm reproduction, we propose that analysis of pollination drop protein (PDP) variation could be used as an alternative method to resolve gymnosperm phylogeny. PDP variation was analyzed at three taxonomic levels: genus, family, and gymnosperm clade. Based on variation in SDS-PAGE banding patterns, identified peptides, amino acid sequences, and protein identification, we conclude that PDP variation has a phylogenetic component. Further research is necessary to develop this method into a tool used to predict phylogenetic relationships. Based on protein identifications, there is strong evidence that the pollination drop functions in both pathogen defense and pollen development. The observation of hydrogen peroxide and peroxidase activity in the ovular secretions of J. communis, C. lawsoniana, Pseudotsuga menziesii (Douglas fir), and Larix x marschlinsii (hybrid larch) provided further support for the assumed functions of ovular secretions.

Terrestrial orchids make up one of the most threatened groups of plants in Australia and the genus Arachnorchis is listed as the fourth most threatened. The process of propagation and re-introduction of terrestrial orchid plants to the wild has proven difficult, and so far, nearly impossible for some species. This may be partly because terrestrial orchids form complex relationships with mycorrhizal fungi and in genera like Arachnorchis the dependency on the fungus appears acute. Arachnorchis has long been considered by amateur growers of terrestrial orchids as one of the most difficult groups to propagate and maintain in cultivation. This lack of knowledge on how to grow Arachnorchis species hinders attempts made by conservation authorities to supplement threatened wild populations in order to achieve a more sustainable future for those species. Natural pollination was absent, but artificial pollination achieved 100% capsule production. Individuals were self-fertile, although seed viability was greater for cross-pollinated samples. This study attempted to track the fate of as many Arachnorchis species as possible from germination through to deflasking and re-emergence, and so destructive and potentially destructive measurements at earlier stages were avoided. This thesis examines germination and subsequent growth of up to eight species of Arachnorchis, but concentrated on A. phaeoclavia, A. tentaculata, A. fulva, A. robinsonii and A. venusta. Two of these are common species: A. pha eoclavia and A. tentaculata, and three carried a threatened classification of &quotrare" or " endangered": A. fulva, A. robinsonii and A. venusta. This study monitored the fate of individuals of the endangered A. fulva in the field and showed that large reproductive plants re-emerged and flowered each year, whereas smaller individuals might be absent in one or more years and were less likely to flower. Germination of all species concentrated on using symbiotic culture (using mycorrhizal fungi), since germination is known to be more rapid, resulting in healthier, more robust seedlings than when plants are grown asymbiotically. Tests using A. fulva and A. venusta, two threatened species, showed similar viability to A. tentaculata and A. phaeoclavia, more common species. Germination was maximised by examining the viability of seeds before and after treatment with surface-sterilising solutions required for aseptic culture. The highest levels of germination, with limited contamination, were achieved using 0.5% available chlorine for 3 minutes. The most effective fungal isolates (&gt65% germination) were obtained from common species like A. phaeoclavia and A. tentaculata, but there was no correlation between germination and time of year or life stage of the orchid. Collar collection was shown to be non-fatal to robust orchid plants, with large reproductive individuals (at the time of collar collection) re-emerging in the next year and producing a flower bud. Collar collection from small, weedy individuals could be fatal to the plant and isolation of an effective fungus was unlikely. Cross-inoculating seeds with fungi isolated from a different orchid species was not recommended, since the symbiosis failed in all experiments, as late as Stage 4 protocorm development. A range of substrates was used to produce strong seedlings capable of surviving the transfer to nursery conditions with minimal loss. More than 81% of seedlings survived deflasking from non-agar substrates, while the best result from agar was 55%. Some substrates reduced the time involved from seed to plants in the field to as little as 4 months, but aftercare became critical. Sucrose promoted tuberisation, but led to tuber deaths during dormancy. Potting mixes were tested in the nursery and a free-draining loam mix based on a mix used by the Australasian Native Orchid Society was the best medium for deflasking of seedlings. Watering during dormancy should be avoided. The choice of propagule for re-introduction was examined and the best survival to re-emergence was obtained by planting out actively growing seedlings in autumn. Identification of cultures using classical morphology grouped cultures as belonging to the form-genera Epulorhiza and Moniliopsis and suggested that most cultures contained more than one fungus. Identification of the most useful fungal cultures was attempted using molecular techniques such as sequencing the ITS region and mitochondrial DNA. One effective culture, CALAPHAER18 SHTX (cultured from a single monilioid cell) was identified as Serendipita vermifera (Oberwinkler) Roberts. All other cultures tested were mixtures of fungi. The use of specific primers designed to amplify a sequence present in the identified isolate (CALAPHAER18 SHTX) showed that nine mixed cultures also contained a fungus most closely related to Serendipita vermifera. Specific primers also showed that Rhizoctonia solani was not present in any of the 10 isolates from Arachnorchis plants. The molecular work showed that, although the sequenced endophytes from Arachnorchis were all most closely related to Serendipita vermifera, three dist inct groups of fungi were present and these associated with separate species of Arachnorchis. Future work with Arachnorchis species will require the isolation of single fungus cultures and further examination of the development of the orchid plant. In particular, the process of tuberisation and growth in vitro on various non-agar substrates should be investigated further.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.

Thesis (Ph.D.) -- University of Western Sydney, Hawkesbury, 1999. / Thesis submitted for the degree of Doctor of Philosophy. Includes bibliographical references (leaves 210-230).

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 96-112).

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

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.