Anatomical features, scientists know, come and go. The animal kingdom is full of critters that have independently gained or lost similar features. Whales and snakes, for instance, have lost their legs. Winged flight evolved separately in birds, bats and pterosaurs at different times in evolutionary history.
Now, writing today (April 20, 2006) in the journal Nature, a team of scientists from the Howard Hughes Medical Institute (HHMI) at the University of Wisconsin-Madison, reveal the discovery of the molecular mechanisms that allow animals to switch genes on or off to gain or lose anatomical characteristics.
"Evolution can and does repeat itself," says Sean B. Carroll, a UW-Madison genetics professor and senior author of the new Nature report that describes how males of different fruit fly species have independently gained -- and repeatedly lost -- the wing spots that make them appealing to females.
"These spots have appeared and disappeared independently in different species at different times over the course of evolutionary history, and have been junked at least five times in one particular group," says Benjamin Prud’homme, a UW-Madison post-doctoral fellow working in Carroll’s lab and the lead author of the new study. "We have shown that each of these transitions corresponds with changes in how a certain gene is used."
The new study reveals how evolution occurs at the finest level of detail and explains the molecular mechanisms at work when animals lose or gain features. In the fruit fly, a gene known as "yellow" is responsible for the fly’s wing decoration.
"The gene is like a paintbrush," says Carroll. "But it needs instructions as to where to paint. Little switches embedded in DNA around the gene have the instructions. It is these switches that are evolving. The fly can lose a spot because of a very small change in his spot switch."
Known as "regulatory elements," the switches that govern gene activity are DNA sequences that act like toggles to turn genes on or off. Individual genes can have several switches, Carroll notes, each one devoted to controlling the gene in a different tissue or body part.
In the case of fruit flies, the changes in the switches’ activity are driven by the preferences of females. The flies meet on flowers and the male fly -- to put the female in the mood -- waves his wings and displays his conspicuous wing spots.
"Female preference is a strong force in the evolution of anatomy," explains Prud´homme. "This phenomenon -- sexual selection -- is all over the animal kingdom. It was one of Darwin’s great ideas."
Finding the same gene and the same processes at work -- molecular switch evolution -- in two distantly related species of fly is remarkable, according to Carroll, because it shows how and why evolution repeats itself.
"The funny thing is they came up with the same solution," Carroll says. "The big picture is that we are seeing the repetition of evolution -- in animals widely divergent in time and space -- at several key levels."
Sean B. Carroll | EurekAlert!
Lethal combination: Drug cocktail turns off the juice to cancer cells
12.12.2018 | Universität Basel
Smelling the forest – not the trees
12.12.2018 | Universität Konstanz
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
12.12.2018 | Health and Medicine
12.12.2018 | Physics and Astronomy
12.12.2018 | Health and Medicine