SELECTION ON POLEMONIUM BRANDEGEEI (POLEMONIACEAE) FLOWERS UNDER HUMMINGBIRD POLLINATION: IN OPPOSITION, PARALLEL, OR INDEPENDENT OF SELECTION BY HAWKMOTHS?
Version of Record online: 4 APR 2013
© 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.
Volume 67, Issue 8, pages 2194–2206, August 2013
How to Cite
Kulbaba, M. W. and Worley, A. C. (2013), SELECTION ON POLEMONIUM BRANDEGEEI (POLEMONIACEAE) FLOWERS UNDER HUMMINGBIRD POLLINATION: IN OPPOSITION, PARALLEL, OR INDEPENDENT OF SELECTION BY HAWKMOTHS?. Evolution, 67: 2194–2206. doi: 10.1111/evo.12102
- Issue online: 26 JUL 2013
- Version of Record online: 4 APR 2013
- Accepted manuscript online: 11 MAR 2013 03:17PM EST
- Manuscript Accepted: 14 FEB 2013
- Manuscript Received: 4 AUG 2012
- NSERC Discovery
- University of Manitoba
- Floral selection;
- male fitness;
- pollen movement;
- selection gradients
Particular floral phenotypes are often associated with specific groups of pollinators. However, flowering plants are often visited, and may be effectively pollinated by more than one type of animal. Therefore, a major outstanding question in floral biology asks: what is the nature of selection on floral traits when pollinators are diverse? This study examined how hummingbirds selected on the floral traits of Polemonium brandegeei, a species pollinated by both hummingbirds and hawkmoths. In array populations of P. brandegeei, we measured pollen movement, and female (seeds set) and male (seeds sired) fitness under hummingbird pollination. We then compared the patterns of selection by hummingbirds with our previous study examining selection by hawkmoths. We documented contrasting selection on sex organ positioning through female function, with hummingbirds selecting for stigmas exserted beyond the anthers and hawkmoths selecting for stigmas recessed below the anthers. Furthermore, hummingbirds selected for longer and wider corolla tubes, and hawkmoths selected for narrower corolla tubes. Therefore, contrasting selection by hawkmoths and hummingbirds may account for variation in sex organ arrangements and corolla dimensions in P. brandegeei. We documented how floral traits under selection by multiple pollinators can result in either an intermediate “compromise” between selective pressures (sex organs) or apparent specialization (corolla tube length) to one pollinator.