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Plant Reproductive Ecology

Dr Glenda Vaughton Senior Lecturer Phone: 02 6773 2595 Fax: 02 6773 3283 E-mail: gvaughto@metz.une.edu.au

Teaching:
ECOL 307 Plant population ecology.

Research interests:
My research focuses on the ecological and genetic factors that shape patterns of variation in reproductive traits in natural plant populations. This research integrates manipulative studies in the field and glasshouse, and laboratory-based tools such as microscopy and electrophoresis. The dual focus of ecology and genetics provides opportunities to conduct both theoretical and applied research.

Current research projects:

• Sex expression and the evolution of dioecy in Wurmbea
• Ecology and evolution of selfing in Banksia marginata
• Determinants of seed production in plant populations.
• Seed size and seed number tradeoffs in Banksia
• Geographic variation in life histories in Burchardia umbellata.
• Effects of introduced honeybees on native plants
• Reproduction and recruitment in populations of rare plants

In dioecious Wurmbea dioica, male flowers are larger than female flowers and males receive 50% more visits by pollinators than females. Males with larger flowers achieve higher reproductive success than plants with smaller flowers, supporting the view that selection for larger flower size has occurred through male function rather than female function.

The nitrogen and phosphorous content of seeds increases with seed size in Banksia marginata and B. spinulosa, and larger seeds produce larger seedlings than small seeds. Although stabilising selection should eliminate seed mass variation within plants, such variation persists because resource constraints limit the ability of plants to control individual seed size.

Pre-dispersal seed predation by parrots and post-dispersal seed predation by rodents dramatically reduce the number of seeds entering the soil seed bank in the rare shrub, Grevillea barklyana. The size and dynamics of the seed bank may limit recruitment in this species.

Seed set in many plant populations is pollen limited. Quantifying the relative importance of pollen quantity and pollen quality in limiting seed set are necessary to understand the functional significance and evolution of floral traits. In Burchardia umbellata, genetically related pollen deposited on stigmas caused interference in the style and ovary, reducing fertilizations by cross pollen. Our study demonstrates adverse effects of interference under natural conditions, and indicates that inappropriate pollen deposition may contribute to pollen limitation more often than previously recognized.

Some examples of recent publications:

Vaughton G, Ramsey M 2003. Self-compatibility in subdioecious Wurmbea dioica (Colchicaceae). Australian Journal of Botany 51.

Vaughton G, Ramsey M 2002. Evidence of gynodioecy and sex ratio variation in Wurmbea biglandulosa (Colchicaceae). Plant Systematics and Evolution 232: 167-179.

Ramsey M, Vaughton G 2002. Maintenance of gynodioecy in Wurmbea biglandulosa (Colchicaceae): Gender differences in seed production and progeny success. Plant Systematics and Evolution 232: 189-200.

Vaughton, G. and Ramsey, M. 2001. Relationships between seed mass, seed nutrients, and seedling growth in Banksia cunninghamii (Proteaceae). International Journal of Plant Sciences 162: 599-606.

Ramsey, M. and Vaughton, G. 2001. Sex expression and sexual dimorphism in subdioecious Wurmbea dioica (Colchicaceae). International Journal of Plant Sciences 162: 589-597.

Vaughton, G. and Ramsey, M. 2001. Variation in summer dormancy in the lilioid geophyte, Burchardia umbellata (Colchicaceae). American Journal of Botany 88: 1223-1229.

Ramsey, M. and Vaughton, G. 2000. Interference by self pollen intensifies pollen limitation of seed set in Burchardia umbellata (Colchicaceae). American Journal of Botany 87: 839-865.

Ramsey M. and Vaughton G. 2000. Pollen quality limits seed set in Burchardia umbellata (Colchicaceae). American Journal of Botany 87: 845-852.

Vaughton G. and Ramsey M. 1998. Floral display, pollinator visitation and reproductive success in the dioecious perennial herb Wurmbea dioica (Liliaceae). Oecologia. 115: 93-101.

Vaughton G. and Ramsey M. 1998. Sources and consequences of seed size variation in the shrub Banksia marginata (Proteaceae). Journal of Ecology, 86: 563-573.

Vaughton G. 1998. Soil seed bank dynamics in a rare obligate seeding shrub, Grevillea barklyana (Proteaceae). Australian Journal of Ecology, 23:375-384.

Ramsey M. and Vaughton G. 1998. Effect of environment on the magnitude of inbreeding depression in a partially self-fertile perennial herb (Blandfordia grandiflora, Liliaceae). International Journal of Plant Sciences, 159: 98-104.

Vaughton G. and Ramsey M. 1997. Seed mass variation in the shrub Banksia spinulosa (Proteaceae): Resource constraints and pollen source effects. International Journal of Plant Sciences, 158: 424-431.

Vaughton G. 1996. Pollination disruption by European honeybees in the Australian bird- pollinated shrub, Grevillea barklyana (Proteaceae). Plant Systematics and Evolution, 200: 89-100.

Ramsey M. and Vaughton G. 1996. Inbreeding depression and pollinator availability in a partially self-fertile perennial herb (Blandfordia grandiflora, Liliaceae). Oikos, 76: 465-474.