The Ophrys Genus

           The Ophrys genus belongs to the Orchidaceae family and contains approximately 30 species. These species are native to Eurasia and North Africa. All have metallic-coloured, hairy flowers that resemble insects (Ophrys 2015). Male insects are lured to the orchid by visual cues and chemical signals. At close range, these signals elicit sexual behaviour in males, whereby the males try to copulate with the flower (Ayasse, et al., 2000). During this process, commonly called pseudocopulation, pollen sacs become attached to the insect’s body and are transferred to the next flowers visited. The fly orchid (O. insectifera) and the bee orchid (O. apifera) are common European species (Ophrys 2015).

Ophrys species are interfertile, meaning they are capable of interbreeding. It is because of this interfertility that reproductive isolation among taxa heavily depends on specific pollinator interaction. Floral odour differences between plant species have often been interpreted as an adaptation to the attraction of distinct pollinators (Dodson et al. 1969). For Ophrys species that are often strongly pollinator limited, selection pressures are imposed by pollinators with different sex pheromone preferences (Ayasse et al. 2000). This pressure is thought to drive floral odour differentiation among orchid populations, ultimately generating adaptive change and species divergence through pollinator shifts (Schiestl and Ayasse 2002).

This genus is a spectacular example of deception and Batesian mimicry in plants. Due to the Ophrys species’ high dependence on specific pollinator interactions, a commensalistic relationship has developed. I can imagine in 50 years the pollinators will have developed a way to identify this deception, however, in the far future it is sure to become a fantastic example of coevolution.

 References

Ayasse, M. et al., 2000. Evolution Of Reproductive Strategies in the Sexually Deceptive Orchid Ophrys sphegodes: How Does Flower-specific Variation of Odor Signals Influence Reproductive Success?. Evolution, 54(6), pp. 1995-2006.http://www.bioone.org/doi/pdf/10.1554/0014-3820%282000%29054%5B1995%3AEORSIT%5D2.0.CO%3B2
Ophrys. 2015. Encyclopædia Britannica Online. Retrieved 22 March, 2015, from http://www.britannica.com/EBchecked/topic/430060/Ophrys

Schiestl, F. P., and M. Ayasse. 2002. Do changes in floral odorcause speciation in sexually deceptive orchids? Plant Sys. Evol.234:111–119. http://www.researchgate.net/publication/225554285_Do_changes_in_floral_odor_cause_speciation_in_sexually_deceptive_orchids