In a new study from the University of Cambridge, researchers are describing how a South African daisy deceives male pollinators by building fake females on its petals. These fly-like structures, created by the South African daisy Gorteria diffusa, have fascinated scientists for decades.
Each three-dimensional fake fly is quite complex, with hairy bumps and white highlights. As male flies approach the structure and attempt to mate, they inadvertently pollinate the flower.
The Cambridge team has now identified, for the first time, the mechanism behind this elaborate scheme. The experts found three sets of genes that are involved in building the fake female flies.
The researchers were surprised to find that these sets of genes play other roles in the plant as well. One set is responsible for making iron, one makes the roots grow, and the third set controls when flowers are made.
According to the researchers, the three sets of genes work together in the daisy petals to build the fly-like structures. They add iron to change the petal color from reddish-purple to blue-green, make hairs expand on the petal to add texture, and make the flies appear in “random” positions.
“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,” explained study senior author Professor Beverley Glover.
The researchers say the daisy’s petals give it an evolutionary advantage by attracting more male flies to pollinate it.
“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,” said study first author Dr. Roman Kellenberger. “But actually by bringing together three existing sets of genes it has happened much more quickly.”
The study is published in the journal Current Biology.
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