A group of scholars, namely A. Abzhanov, W. P. Kuo, C. Hartmann, B. R. Grant, P. R. Grant, and C. J. Tabin, recently wrote an article entitled “The Calmodulin Pathway and Evolution of Elongated Beak Morphology in Darwin’s Finches.” It was published in Nature 442 (2006):563-567.

Summary. Darwin’s finches of the Galapagos Islands comprise a group of fourteen closely related species, with major differences primarily in their beaks. The ground finches, genus Geospiza, illustrate these differences especially well. The molecule, calmodulin, is produced at higher levels in Geospiza species with long beaks than in those with short beaks. Experimental manipulation of calmodulin production in chickens confirmed its effects in elongation of the upper beak. This finding shows that small changes in gene regulation might account for beak morphological divergence in the Galapagos finches.

Comment. This invaluable example can help explain how the Galapagos finches have diverged morphologically. Beak size and shape is a key character in identifying different types of birds, and this study may help illuminate how some of these differences originated.