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|Title:||Two orchids, one scent? Floral volatiles of Catasetum cernuum and Gongora bufonia suggest convergent evolution to a unique pollination niche|
|Abstract:||Floral volatile organic compounds (VOCs) are important signals in plant-pollinator communication and thus subjected to olfactory-mediated selection. Occasionally, phylogenetically unrelated plant species will converge towards similar patterns of floral scent signalling to harness pollinators, representing a common adaptive pollination niche. Catasetum cernuum and Gongora bufonia, epiphytic orchids that are native to the Atlantic Forest of southeastern South America, are exclusively pollinated by male Eufriesea violacea orchid-bees; we hypothesised that the two species have converged towards similar floral scent compositions to effectively attract these particular fragrance-seeking floral visitors. The similarity of the chemical composition of floral scent samples obtained through headspace collection was tested using multiple approaches of multivariate analyses (Multiple Response Permutation Procedure—MRPP). According to MRPP, floral scents of C. cernuum and G. bufonia are significantly different. Additionally, the floral scents of C. cernuum and G. bufonia present (E)-β-ocimene and (E)-epoxyocimene as their major compounds, respectively. (E)-β-ocimene is a common constituent of floral scents from euglossine-pollinated orchids, while (E)-epoxyocimene is quite rare in orchids’ floral scents and it is found in only a few other species which occur outside the distribution range of C. cernuum, G. bufonia and E. violacea. However, 12 out of the 34 identified VOCs, including (E)-β-ocimene and (E)-epoxyocimene, are shared between both species. Therefore, we assume that both (E)-β-ocimene and (E)-epoxyocimene, either alone or mixed with other floral VOCs, play a major role in the specific association between these two orchids and their exclusive euglossine pollinator.|
|Appears in Collections:||IB - Artigos e Outros Documentos|
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