Schlumpberger, Boris O. , Renner, Susanne S .
Reproductive assurance through secondary pollinators in hawkmoth-adapted cactus flowers.
Floral traits result from selection by predominant pollinators, flower predators, and abiotic factors. In Echinopsis, a large paraphyletic genus of Cactaceae, most species appear adapted to either bees or hawkmoths as pollinators, judging from features such as flower color and time of anthesis. However, the hawkmoth flowers usually remain open the following morning, allowing diurnal visitors, such as bees, to gather any remaining pollen. We studied six hawkmoth-pollinated species with white flowers (16 to 25 cm long) from different clades to assess the effectiveness of nocturnal moths relative to diurnal bees as pollinators. Moth scales on flower stigmas proved moth visitation in each of the species, and nectar quantities were usually high, surpassing nectar amounts in closely related bee-pollinated taxa (with relatedness judged from a molecular phylogeny). Pollinator exclusion experiments during one season at three locations and on three species revealed different extents of nocturnal pollination, viz. 10, 33, and 71 percent of nocturnal pollination. Remarkably, fruit set in diurnally exposed flowers of the same species at the same locations was higher in all cases (16, 83, and 86%) and was entirely due to pollen-gathering solitary bees. Openly exposed control flowers had fruit sets of 25, 100 and 91%. These results demonstrate the role of bimodal pollination in reproductive assurance, which may set the stage for evolutionary shifts between nectar-reward-driven moth pollination and pollen-reward-driven bee pollination.
Log in to add this item to your schedule
1 - University of Munich, Organismal Biology, Menzingerstr. 67, Munich, 80638, Germany
Presentation Type: Poster:Posters for Topics
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM