Fine scale distribution of pollinator explains the occurrence of the natural orchid hybrid × Orchis bergonii

Abstract

:Hybridization is frequent in Orchidaceae and may play an important role in their speciation. However, information about pollinators and their role in hybridization is sparse. In the Mediterranean region of France, confirmed pollinatorsobserved on Orchis simia and O. anthropophora included only one species common to both, the beetle Cidnopus pilosus. This beetle thus appears responsible for hybridization. Cross-specific pollen transfer is bidirectional, but hand pollination showed higher fruit set after deposition of O. anthropophora pollen on the stigma of O. simia than in the opposite direction. Both locally and over a 1600-km2 study area, the presence of hybrids was shown to be strongly predicted by the microhabitat preferences of this beetle. To my knowledge, this is a novel demonstration that the spatial distribution of a natural hybrid in plants can be predicted by the local occurrence of a pollinator species identified as effecting hybridization. I suggest that similar interaction could explain the distribution of hybrids in other orchid species pairs.