Together, those percentages would suggest that deceitful pollination could represent close to half of all pollination syndromes in orchids. If confirmed to be a generalized syndrome in these species-rich groups, sexual deceit might well represent up to 10 % of the pollination syndromes in Orchidaceae. Sexual deception has been reported in several phylogenetically unrelated orchid clades ( van der Pijl and Dodson, 1966 Adams and Lawson, 1993 Singer, 2002 Ayasse et al., 2003 Singer et al., 2004 Blanco and Barboza, 2005 Ciotek et al., 2006 Phillips et al., 2009 Peakall et al., 2010). Food deception has evolved repeatedly in different angiosperm groups, but is mostly restricted to a few species per family ( Renner, 2005), whereas estimates suggest that a third of all orchids might be food-deceptive ( Ackerman, 1986), and it seems to have arisen many times independently in Orchidaceae. Pollination by deceit is well known among orchids and has been frequently considered another key innovation contributing to the high species richness of the family ( van der Pijl and Dodson, 1966 Cozzolino and Widmer, 2005). Orchids frequently exploit existing plant–pollinator relationships or even sexual systems of insects, exemplified by species that achieve pollination through deception, not offering floral rewards ( Ackerman, 1986 Jersáková et al., 2006 Ramírez et al., 2011). (2006) argued that this adaptation is probably unilateral, without change in the pollinator ( Williams, 1982), and co-evolution between orchids and their pollinators is apparently uncommon ( Szentesi, 2002). Nonetheless, pollinator adaptation might be the driving force of the remarkable floral diversification in orchids. The combination of pheromone attraction and nectar feeding is likely to be a generalized pollination syndrome in Pleurothallidinae.Įpiphytism is likely to be the major contributor to the species richness in Orchidaceae, more specifically Epidendroideae ( Gravendeel et al., 2004). It is not expected that Specklinia species will hybridize naturally as their populations do not overlap geographically. There seem to be no species-specific relationships between the orchids and the flies. endotrachys group share a similar pollination syndrome. Several different Drosophila species can be found on a single Specklinia species.Ĭonclusions Species of the S. The flies frequently show courtship behaviour, occasionally copulating. Visible nectar drops on the adaxial surface of sepals are secreted by nectar-secreting stomata, encouraging male and female Drosophila to linger on the flowers for several hours at a time. The flies are arrested by aggregation pheromones, including ethyl tiglate, methyl tiglate and isopropyl tiglate, released by the flowers, and to which at least D. spectabilis are visited and pollinated by several different but closely related Drosophila species. Floral compounds were analysed by gas chromatography–mass spectometry using those same pheromones as standards. Electroantennogram experiments were carried out on Drosophila hydei using the known aggregation pheromones ethyl tiglate, methyl tiglate and isopropyl tiglate. Tissue samples of the sepals, petals and labellum of Specklinia species were observed and documented by SEM, LM and TEM. Flies were photographed, filmed and observed for several days during a 2-year period and were identified by a combination of non-invasive DNA barcoding and anatomical surveys. Methods Specimens of Specklinia and Drosophila were collected in the field in Costa Rica and preserved in the JBL and L herbaria. endotrachys complex are pollinated by different Drosophila species. This study documents and describes how species of the S. Chase would later identify the visiting flies as being members of the genus Drosophila. Background and Aims The first documented observation of pollination in Pleurothallidinae was that of Endrés, who noticed that the ‘viscid sepals’ of Specklinia endotrachys were visited by a ‘small fly’.
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