In this project I studied the importance of pollinators in the reproduction of Gastrodia ‘long column’ and the preferences of New Zealand’s native and exotic insect pollinators. This was done in order to determine the specialisation of insect pollination in urban Christchurch. This knowledge can contribute to crop pollination, conservation efforts, and an understanding of the main drivers of the common floral traits (small, white flowers) in New Zealand. The strength of the relationship between the common traits of the New Zealand flora and the preferences of the native invertebrate fauna is not known. Traditionally it had been thought that New Zealand’s insects lack strong preferences, however recent work has not supported this. Changing landscapes worldwide have led to declines in pollinator numbers. Additionally, in New Zealand Apis mellifera numbers have declined as a result of the arrival of the varroa mite and it is important that alternative pollinating species for wild and agricultural pollination are identified. To address these needs I examined the abundance and preferences of insect pollinators in modified landscapes in and around Christchurch testing: the reliance upon pollinators by the undescribed native orchid Gastrodia ‘long column’, the preferences of New Zealand’s native and introduced insect pollinators in an extensive observational study, the results of which I further tested using a subsequent manipulative experiment of petal colour (according to human vision) at the Christchurch Botanical Gardens Sampling at the Christchurch Botanical Gardens, University of Canterbury, and Port Hills across a four month observation period (January – April 2012), revealed that native pollinators preferred white native flowers and exotic pollinators preferred not-white exotic flowers when data were grouped according to insect provenance. A more detailed visit-level analysis found that two native bees, Hylaeus and Leioproctus, showed a significant preference for native flowers; the exotic bees, Apis mellifera and Bombus species, preferred purple over white flowers; and Melangyna novaezelandiae (a native hoverfly) preferred white over yellow. However, a series of experimental arrays to present controlled choices between pairs of flower types at the Christchurch Botanical Gardens (14 December 2012 – 22 January 2013) did not find significant preferences by native or exotic insect pollinators between white and yellow flowers. This may have been a result of the plant species chosen, as a correlation between pollinator preference and plant species has been shown elsewhere. Visitation to experimental arrays was both low and highly skewed, with over half of all visits made by Lasioglossum bees and 615 of the 669 visits made by native species. This may have meant that lack of significant results were representing the choices of native insects generally and Lasioglossum bees specifically. A bagging experiment from 30 January 2012 – 16 February 2012 demonstrated the dependence of the undescribed native orchid species, Gastrodia ‘long column’, upon pollinating animals. Fruit set of most plants worldwide depends upon pollination (by wind or animal-transfer of pollen). In this case study final fruit sets were significantly reduced on bagged inflorescences, while open flowers had surprisingly high natural fruit sets (>75%). A week of observations (29 January 2012 – 6 February 2012) revealed that Gastrodia ‘long column’ was predominantly visited by Lasioglossum bees, and remarkably bee numbers were high enough in a residential property in the middle of Christchurch city for high fruit set on unmanipulated plants. The results of my thesis indicate that pollinators are important in the reproductive system of Gastrodia ‘long column’, suggesting that other previously overlooked plant species may also rely upon insect pollinators. Furthermore, the relative importance of native pollinating insects is high for native plants even when examined in an urban setting. New Zealand pollinators have preferences for certain floral traits which show trends when grouped broadly, but vary when considered at the insect species level. This contrasts with traditional views of unspecialised insect pollinators which lack preferences in regards to the plants they visit. Further work which serves to increase current understanding of the underlying mechanisms of pollination specialisation in New Zealand may wish to focus on single insect species. By identifying particular preferences of pollinators and the underlying ‘native’ traits selected for, alternative options to crop pollination may be found, targeted management strategies implemented, and the strength of the relationship between pollinator preferences and the traits of the plants they visit determined.

The evolution of wind pollination (anemophily) has occurred at least 65 times in the flowering plants and over 10% of angiosperm species are wind pollinated. However the pollination and mating of anemophily species is poorly understood, particularly in comparison with animal-pollinated species. My thesis employs a range of approaches and tools to examine the evolution and ecology of wind pollination. These include comparative analyses, theoretical modeling, field and glasshouse experiments, the use of genetic markers and quantitative genetics. Experimental studies on diverse taxa were used to address questions concerned with the efficacy of outcrossing mechanisms, the ecological and demographic context of pollination and mating, and the plasticity of sex allocation. Comparative analyses indicated that wind pollination is correlated with unisexual flowers, reduced ovule number, small unshowy flowers, an absence of nectar, and open habitats. These analyses also demonstrated that anemophily originates more often in lineages with unisexual flowers. This suggests that wind pollination evolves in diclinous taxa as a mechanism of reproductive assurance because autonomous selfing is mechanically precluded. Empirical data on stigmatic pollen loads in 19 anemophilous species challenge the widespread assumption that anemophilous plants commonly have uniovulate flowers because they capture few pollen grains. Further, a model based on floral costs and the aerodynamics of pollen capture demonstrated that when flowers are inexpensive it is optimal to produce many flowers each with few ovules, because this allows more efficient sampling of the airstream. Manipulative field experiments on seven Carex species indicated that neither monoecy nor protogyny, two putative outcrossing mechanisms, are effective at limiting selfing. Based on these results I suggest that geitonogamy can provide reproductive assurance in anemophilous species with unisexual flowers. Field experiments and the application of sex-specific markers in Rumex nivalis revealed that the local neighbourhood of maternal plants affects pollination intensity and progeny sex ratios. Finally, I demonstrated that plant density in Ambrosia artemisiifolia affects stigmatic pollen loads but not outcrossing rates. Through a quantitative genetics experiment in A. artemisiifolia, I detected significant genetic variation for plasticity in sex allocation, potentially enabling adaptive adjustment of sex allocation to local environmental conditions.

Bibliography: leaves 186-209. / xiii, 209 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 1995

Bibliography: leaves 143-150. / xxii, 150 leaves : col. ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Isozyme analysis was carried out on sweet cherry (Prunus avium) leaves. Cultivars were identified and compared. Progeny from controlled hybridisations were examined to determine inheritance patterns of isozymes. Isozymes were also used to determine gene flow in cherry orchards and to determine pollen donors of selected cultivars. / Thesis (Ph.D.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, (1996?)

Thesis (M.A.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on November 6, 2007) Includes bibliographical references.

Thesis (M. Ag. Sci)--University of Adelaide, 1987. / Includes bibliographical references (leaves 256-323).

Thesis (Ph.D.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: p. 262-287.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains vi, 50 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Department of Biochemistry and Molecular Biology, March 2003. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1999. / Typescript. Vita. Includes bibliographical references (leaves 246-266). Also available on the Internet.