The evolution of flowering phenology is the result of a trade-off that balances many factors, including growth, reproductive capacity, and temporal overlap with pollinators. When there is large temporal variation in temperature, particularly in the onset of frost, the optimum flowering strategy will vary from year to year. In Duluth, MN, USA, the end of the growing season can vary by more than 30 days. In this study, we observed flowering phenology and pollinator abundance on 15 genotypes of Solidago altissima in Duluth, MN. We predicted that temporal variation in temperature would lead to a range of flowering strategies in the S. altissima population; some genotypes flower early and in synchrony, some 'hedge their bets' by flowering over a range of dates, and others have an intermediate strategy. Our results indicate that genotypes vary in mean flowering date and duration of flowering and, for the two observed years, pollinator abundance was highest for early-flowering genotypes.
Bibliographical noteFunding Information:
Funding was provided by National Research Foundation grant DEB 0949280 awarded to T.P. Craig and J. K. Itami and Department of Biology, the University of Minnesota, Duluth, MN, USA. J.K. Itami prepared the figures. We would like to thank E. Kalkbrenner, B. Loeks, J. Menchaca, L. Craig, P. Craig, N. Zarnstorff, W. Licht, D. Johnston, and P. Lande for their assistance in data collection.
- Flowering phenology
- Solidago altissima
- Temporal variation