PARENT SESSION
Poster Session 35: Evolutionary Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Costs and benefits of asynchronous flowering in the beetle pollination of dichogamous trees.
Ishida, Kiyoshi*,1, 1 Kansai Research Center, Forestry and Forest Products Research Institute, Kyoto, Kyoto, Japan
ABSTRACT- Temperate dichogamous trees that pollinated by beetles often exhibit asynchronous flowering (display of female- and male-phase flowers simultaneously). The beetles stay in male-phase flowers to feed pollen, which would result in decreased interfloral-pollination. If beetles leave the tree before arriving male-phase flowers, outcrossed siring success would also reduce. Hence asynchronous flowering may be evolutionarily unstable compared to synchronous flowering (temporal separation of male- and female-phase flowers) in the dichogamous trees unless these costs are compensated by its benefits. I present phenotypic models to examine costs and benefits of asynchronous flowering and conditions facilitating this mode of flowering in the beetle pollination of dichogamous trees. If we assume the decreased interfloral-pollination and reduced siring success as costs and reduced geitonogamy due to decreased male-phase flowers per day (beetles cause geitonogamy the next day after leaving male-phase flowers) as a benefit in asynchronous flowering, then the model indicates that the following three conditions contribute the maintenance of asynchronous flowering: (1) high inbreeding depression, (2) frequent geitonogamy, and (3) short male-phase period of individual flowers. If asynchronous flowering does not reduce geitonogamy because of effective automimicry or rewarding female-phase flowers (no beetles leave before arriving male-phase flowers), then the model indicates that this mode of flowering is evolutionarily unstable even if the automimicry maintains siring success. These results help to explain the maintenance of asynchronous flowering in some temperate magnolias that exhibit frequent geitonogamy and high inbreeding depression.
Key words: geitonogamy, inbreeding depression, automimicry, magnolias