Zygomorphic flowers last longer: the evolution of floral symmetry and floral longevity

ID: 613 / 308

Category: Abstract

Track: Pending

Proposed Symposium Title: Zygomorphic flowers last longer: the evolution of floral symmetry and floral longevity


Ruby E. Stephens1,2,3, Rachael V. Gallagher1,4, Marcos Méndez5, Hervé Sauquet2

Affiliations: 1 School of Natural Sciences, Macquarie University, Ryde, NSW, Australia 2 Royal Botanic Gardens and Domain Trust, Sydney, NSW, Australia 3 Ecology & Evolution Research Centre, University of New South Wales, Sydney, NSW, Australia 4 Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, NSW, Australia 5 Area of Biodiversity and Conservation, Universidad Rey Juan Carlos, Madrid, Spain


Floral symmetry has long been considered a key trait in floral evolution. Although zygomorphic (bilaterally symmetric) flowers typically receive fewer floral visitors, it is yet to be determined whether this translates to a slower rate of pollination. Floral longevity, the time from flower anthesis to senescence, is an evolved trait which balances floral costs against the rate at which flowers are pollinated. Using newly collected field data combined with data compiled from the literature we assess whether floral longevity varies with floral symmetry. Phylogenetic regressions show that zygomorphic flowers last longer than actinomorphic flowers, though there is considerable variation in longevity in both groups. Zygomorphic flowers opened on average for 4.7 days, whereas actinomorphic flowers typically lasted 3.6 days. Our results provide further evidence of the costs of zygomorphy for flowers. Despite these costs, zygomorphy has evolved numerous times throughout angiosperm history, and the reward of more targeted pollination, and lower pollen interference must be worth having to keep your flowers open for longer.

Symposia selection: 175, 76, 128

Key words: Floral morphology, cost-benefit, floral evolution, phylogeny, comparative method