Cunning trick used by daisy to trick male flies is explained by Cambridge plant scientists
A cunning trick used by a South African daisy to encourage male flies to pollinate it has been explained by Cambridge researchers.
Incredibly, the daisy creates what looks like lady flies on its petals to attract the males.
When a male lands on top of one, he jiggle around in an attempt to mate but discovered it doesn’t quite work. He might have another go, before giving up and buzzing off, unsuccessful. But the plant has got what it wanted: pollen.
The South African daisy, Gorteria diffusa, is the only daisy known to make such a complicated three-dimensional structure resembling a female fly on its petals.
The mechanism behind this deception, which has hairy bumps and white highlights, has intrigued scientists for decades.
Now researchers at the University of Cambridge have identified three sets of genes involved. They were surprised to find all three sets already have other functions - one moves iron around, one makes root hairs grow, and one controls when flowers are made.
The genes were brought together in a new way to build the fake lady flies.
The ‘iron moving’ genes add iron to the petal’s normally reddish-purple pigments, changing the colour to a more fly-like blue-green, while the root hair genes make hairs expand on the petal to give texture. The third set of genes make the fake flies appear in apparently random positions on the petals.
Prof Beverley Glover in the University of Cambridge’s Department of Plant Sciences and director of the university’s Botanic Garden, is senior author of the study, published in the journal Current Biology.
She said: “This daisy didn’t evolve a new ‘make a fly’ gene. Instead it did something even cleverer - it brought together existing genes, which already do other things in different parts of the plant, to make a complicated spot on the petals that deceives male flies.”
The petals give the daisy an evolutionary advantage, by attracting more male flies to pollinate it.
Since they grow in a harsh desert environment in South Africa, with only a short rainy season in which to produce flowers, get pollinated and set seed before they die, there is great competition to attract pollinators.
In evolutionary terms, the daisy is very young at 1.5 to two million years old. The earliest daisies of this family tree did not have the fake fly spots, which means they must have appeared on the daisy petals very rapidly.
“We’d expect that something as complex as a fake fly would take a long time to evolve, involving lots of genes and lots of mutations. But actually by bringing together three existing sets of genes it has happened much more quickly,”said Dr Roman Kellenberger, a postdoctoral researcher in the University of Cambridge’s Department of Plant Sciences and first author of the study.
“It’s almost like evolving a whole new organ in a very short time-frame. Male flies don’t stay long on flowers with simple spots, but they’re so convinced by these fake flies that they spend extra time trying to mate, and rub off more pollen onto the flower – helping to pollinate it,”