Policha, Tobias , Manobanda, Rocio , McAlpine, Jesse , Dentinger, Bryn , Roy, Bitty .
Reproductive Biology of Mushroom Mimicking Dracula Orchids.
Pollination biology is fundamentally the study of interactions between a plant and its environment. Floral mimicry adds complexity to this interaction. Dracula orchids look and smell like mushrooms, and are pollinated by mushroom associated flies. One hypothesis is that the plants take advantage of this fungal phenotype to overcome the problems of density-dependent visitation. Like many orchids, neither Dracula felix nor D. lafleurii have very high fruit set rates. D. lafleurii set fruit on only 5.7% of its buds (n=35), while D. felix was somewhat more successful, producing fruit from 45.5% of its buds (n=44). One explanation for the higher rates in D. felix is its capacity for insect-mediated selfing. In a hand pollination experiment, manipulated 'selfed' flowers, geitonogamously pollinated, and out-crossed flowers all set fruit at similar rates, but unmanipulated flowers did not set any fruits (n=102). In support of a density-dependent visitation hypothesis, when number of flowers per plant was regressed against total number of visitors, there was a clear positive relationship (r2 =0.49, p=0.001). The next hypothesis tested was: if these flowers are mimicking fungi, then they should derive some benefit from the resemblance. When assaying visitation rates in different contexts with D. felix, we found not only that flowers next to other flowers received more visits than singleton flowers, but that flowers next to mushrooms received the same number of visits as the 'next to flowers' treatment (n=16 reps; p=0.0199). In D. lafleurii we asked the same question, but instead of single flowers we positioned whole plants either next to mushrooms or by themselves. We again found that plants next to mushrooms had more visits than plants away from mushrooms (n=6reps; p=0.0218). Finally, looking at natural variation in plants that were either near to, or far away from mushrooms, we found a similar pattern (n=4 reps; p=0.0500). Our data support the hypothesis that Dracula orchids derive a benefit from their resemblance to mushrooms.
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Fungal mimicry in the deceptive pollination of Dracula orchids
1 - University of Oregon, Center for Ecology and Evolutionary Biology, 5289 University of Oregon, Eugene, OR, 97403, USA
2 - Quito, Ecuador
3 - Royal Botanic Gardens, Kew, Jodrell Laboratory, Richmond , Surrey, TW9 3DS, UK
Presentation Type: Oral Paper:Papers for Topics
Location: Forsyth Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 8:15 AM