Pollinators to deceptive daisy: Fool me twice, shame on me

Gorteria diffusa

Gorteria diffusa. If its spots look like sexy female bee flies to you, you might be a bee fly yourself. Photo by Flickr/thehumofbees.

The South African daisy Gorteria diffusa has a means of attracting pollinators that is either a mean-spirited or brilliant, depending on how much you sympathize with the pollinators in question: its dark-spotted petals fool male bee flies (Megapalpus capensis) into mating with the flower. This is, of course, a fruitless exercise for the bee fly, but not so for the daisy, since the decieved males pick up pollen in the process, which they’ll transfer to another daisy when they’re fooled again.

This is a bit salacious, but this kind of sexual deception isn’t exactly rare among flowering plants. What makes G. diffusa more interesting, to an evolutionary biologist, is that not all populations of the daisy practice this deception. The pattern of G. diffusa‘s petals varies across its range—and not all petal patterns prompt the pollinators to hump the flower. Actually, on all but three of the various forms of G. diffusa, bee flies mostly just come to feed on nectar.

That poses the interesting evolutionary question of why some populations of G. diffusa have evolved to trick their pollinators, when so many others have not. A paper just released online at the journal Evolution attempts to answer that question—but its authors find more new questions than they do concrete answers.

Continue reading