Orchids “adapt” to colour preferences of pollinators

This hypothesis has been formulated by Hannes Paulus in a contribution for the latest edition of the Journal Europäischer Orchideen (Hannes F. Paulus: Zur Bestäubungsbiologie der Gattung Ophrys in Nordspanien: Freilandstudien an Ophrys aveyronensis, O. subinsectifera, O. riojana, O. vasconica und O. forestieri. J. Eur. Orchideen. 49 (3-4): 427-471).

In this article the author studies both populations of Ophrys aveyronensis in Southern France and Northern Spain – the last one termed as Ophrys aveyronensis subsp. vitorica. According to Paulus it is just one species, because both are pollinated by the bee Andrena hattorfiana.

Paulus points to the fact that this bee is specialised on the widow-flower (Knautia). The pink inflorescence of this plant has the same colour as the perigone, i.e. the sepals and petals, of Ophrys aveyronensis. The expert of Ophrys is stating: It can be expected that this is not just a mere chance but an adaptation to the main nourishing plant of the pollinator. Knautia shows at the same time more deeply pink flowers as flowers tending to white.

This evidence is confirming the approach to also look for other plants when we search for reasons why albiflora forms of different orchid species are more often in certain places.

3 thoughts on “Orchids “adapt” to colour preferences of pollinators”

  1. Indeed, John. The interpretation that orchids adapt to insect behaviour implies an action of the orchid to a certain stimulans. That is not how it works. It is simply a game of a defect being accepted by the pollinating insect or not. When accepted, the defect is “successful”, or better said: not unsuccessful and passed to future generations. The orchid has no control over this as it doesn’t have any feedback mechanism by which it can measure success or failure. Mother Nature simply spits out a million differences and whatever differences are not rejected by the environmental factors (that include other organisms), live on. In rare cases differences are highly favoured and lead to an “explosion” of abberant plants. Orchid hybrid swarms are an example of this and sometimes they differentiate further into a new species. But oftentimes, the abberations are simply assimilated back into the overall population and “disappear”.

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