Their paper, which describes this molecular beak-shaping process, will be published in this week's issue of the journal Science. A report on this paper and another closely related study will appear in the journal's news section.
Different bird species tend to have differently shaped beaks, which are said to reflect the different evolutionary pressures under which they develop. In fact, Charles Darwin looked to 13 different species of finch from the Galapagos Islands to help bolster his theories of evolution, showing that while the Galapagos finches had most likely descended from a common ancestor, they had developed into distinct species based on differences in their beaks-differences which corresponded with their confinement to different islands in the archipelago and their adaptation to different ecological niches.
Today, beak shape is considered "a classical example of evolutionary diversification," writes Cheng-Ming Chuong, M.D., Ph.D., principal investigator on the Science paper and professor of pathology at the Keck School of Medicine, along with his colleagues. Still, while the reason for this diversity is explained by evolutionary selection, little is known about how different beak shapes are built at the cellular and molecular level.
"Since beaks are made from cells, each 'designer beak' must be made through differences in the regulation of cell behaviors," Chuong notes.
Beaks are actually a collection of "facial prominences," says Chuong, and these prominences grow at varying rates during chick development to "compose a unique beak." But while early chicken be
Contact: Jon Weiner
University of Southern California