Scientists have accidentally created a beetle with a third eye.
Researchers at the University of Indiana say their accident could dramatically enhance our knowledge of evolution.
Using a simple genetic tool, they grew a fully functional extra eye in the center of the forehead of the common beetle.
Indiana researchers grew a fully functional extra eye in the center of the forehead of the common beetle by deactivating a single gene.
To create a fully functional eye in the center of a beetle's head, the researchers deactivated a single gene called orthodenticle, or odt, which their research has previously shown to play a role in instructing the formation of the head during development.
The researchers admit the discovery came accidentally as part of a study to understand how the insect head develops.
Unraveling the biological mechanisms behind this occurrence could help researchers understand how evolution draws upon pre-existing developmental and genetic 'building blocks' to create novel complex traits, or 'old' traits in novel places, they say.
The study's results appear in the journal of the Proceedings of the National Academy of Sciences.
'Developmental biology is beautifully complex in part because there's no single gene for an eye, a brain, a butterfly's wing or a turtle's shell,' said Armin P. Moczek, a professor in the IU Bloomington College of Arts and Sciences' Department of Biology.
'Instead, thousands of individual genes and dozens of developmental processes come together to enable the formation of each of these traits.
'We've also learned that evolving a novel physical trait is much like building a novel structure out of Legos, by re-using and recombining 'old' genes and developmental processes within new contexts.'
As a consequence, the evolution of novel features often requires many fewer genetic changes than biologists originally thought.
But unlike rearranging and combining toy plastic bricks to form a new structure, Moczek said it's unclear what biological mechanisms guide the construction of new physical traits under some circumstances but not others.
'You can make new things over and over or in new places using the same old set of 'bricks,'' he said.
'But in Legos, we know the rules of assembly: which pieces go together and which things don't. In biology, we still struggle to understand the respective counterparts.'
One of the ways that scientists have sought to get a clearer view of this process is by coaxing the growth of 'ectopic' organs – or organs that form on the wrong part of the body.
Early work in the field has focused on the formation of fruit fly eyes in