Coevolution and Pollination:
Ophrys : Bee Orchids
Hello readers,
Today the topic is Coevolution and Pollination, and I am going to introduce to to a fascinating Genus of plants called Ophrys, or "bee orchids."
The Bee orchids depend on bees for pollination, so evolutionarily, they had to evolve ways to keep the bees interested and ensure pollination. This should not come as a surprise considering that many plants attract bees to cross pollinate, however, the mechanism this genus uses is quite interesting.
Rather than evolving for just smell or color, bee orchids actually evolved to display a flower in the same shape as the bee itself. The floral mimicry is a tactic to encourage a process known as pseudocopulation. This is when a male bee, seeing what he thinks is a female, will land, attempt to mate, and pollinate the flower. The flower is not only in the shape of the bee, but also releases mimic pheromones, called allomones, that smell like a female.
During pseudocopulation, pollen will stick to the bees head or abdomen. This pollen will travel on the bee until it becomes attracted to another "mate," where pollen exchange can occur and pollination will happen.
I find this story of coevolution particularly interesting, and it brings up many evolutionary questions. Because the bee orchid species depends entirely on the bee, it has devoloped use of deception to suit its purpose. But once the bee has been duped, it may not revisit the flower or the same type of plant again. Do you think this species would have increased its success by developing some other traits?
The coevolution is an extreme example of mutualism, because the bees need flowers just as the flowers need bees. However, mimicry is typically seen in coevolution between prey-predator animals. Do you think the bee orchids are trying to out compete other plants? Or are they just mutual-beneficiaries-turned-frenemies? Do coevolutionary "arms races" occur between mutualistic species?
Please discuss in the comments below! I would love to hear what you think.
Thanks for reading, and have a phenomenal day!
D
Sources:
Borg-Karlson, A. K. (1990). Chemical and ethological studies of pollination in the genus Ophrys (Orchidaceae). Phytochemistry, 29(5), 1359-1387.
Schiestl, F. P. (2005). On the success of a swindle: pollination by deception in orchids. Naturwissenschaften, 92(6), 255-264.
The bee orchid is a wonderful example and particularly fascinating given its mimicking strategy, both morphological and chemical. I was interested by one of your statements – you say that this is a coevolutionary relationship. However, coevolution is a result of evolution of co-adapted gene complexes. Now, orchids need the bees, but the bees don’t actually gain any benefits from these plants – they don’t provide nectar as a reward. So, perhaps this is more an example of a “parasitic” (or commensalistic) symbiosis, rather than coevolution. Your thoughts?
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