Rentsch, Jeremy , Leebens-Mack, Jim .
Yucca aloifolia (Asparagaceae) opts out of an obligate pollination mutualism? Evidence for diurnal non-moth pollination of a Yucca species.
The obligate mutualism between species of the genus Yucca (Asparagaceae) and their seed feeding pollinators has long served as a model for studying highly specialized obligate pollination mutualisms. It has often been asserted that organisms participating in obligate mutualisms are "evolutionary dead ends", prone to extinction because reversion to non-obligate interactions may be impossible. At the same time, some yuccas (including Yucca aloifolia) are documented as producing occasional, sparse fruit sets even when growing outside of the range of pollinating yucca moths. Further, Y. aloifolia populations existing sympatrically with the pollinating yucca moth, Tegeticula yuccasella, can produced large numbers of fruit that lack the oviposition scars expected with moth pollination. Here, we present the results of pollinator exclusion studies performed on Y. aloifolia and a sympatric yucca species, Y. filamentosa, with an earlier flowering time. As expected, Y. filamentosa set fruit almost exclusively when inflorescences were exposed to crepuscular and nocturnal yucca moths. In contrast, good fruit set was observed when pollinators were excluded from Y. aloifolia inflorescences from dusk to dawn, and no fruit set was observed when pollinators were excluded during the day. Follow-up observations and post-visit exclusion experiments indicated that European honeybees (Apis mellifera) were passively yet effectively pollinating Y. aloifolia flowers. These results indicate that even highly specialized mutualisms are not evolutionary dead ends. At the same time, it should be noted that yucca moths have maintained a pollination mutualism with all extant Yucca species including many Y. aloifolia populations since the origin of the genus an estimated 15 million years ago.
Log in to add this item to your schedule
1 - 160 Dudley Drive, APT 526, Athens, GA, 30606, USA
2 - University Of Georgia, 4503 Miller Plant Sciences, Athens, GA, 30602, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Delaware D/Hyatt
Date: Wednesday, July 11th, 2012
Time: 2:45 PM