Surprise, Surprise: Hox Proteins Have Evolved

Image: Courtesy of William McGinnis LOTSALEGS: The six-limbed fruit fly, Drosophila melanogaster As school children are commonly taught, adult insects have six legs. No more, no less. But there's more to this story. The class Insecta is descended from multilimb ancestors, and most other living arthropods, including Insecta's closest living relative, the Crustacea, usually have at least five pairs of legs or leg-like appendages. How insects lost their limbs has interested those in the bu

Leslie Pray
Oct 13, 2002
Image: Courtesy of William McGinnis
 LOTSALEGS: The six-limbed fruit fly, Drosophila melanogaster

As school children are commonly taught, adult insects have six legs. No more, no less. But there's more to this story. The class Insecta is descended from multilimb ancestors, and most other living arthropods, including Insecta's closest living relative, the Crustacea, usually have at least five pairs of legs or leg-like appendages.

How insects lost their limbs has interested those in the burgeoning field of "evo-devo," the study of developmental evolution. In particular, biologists have suspected that the insects' progression to six legs, and the evolution and modification of arthropod appendages in general, are driven by changes in Hox gene activity. Hox genes are clusters of regulatory genes that control development by turning other genes on and off. Biologists had attributed changes in the arthropod body plan to changes in Hox gene expression, not changes in the Hox...

Interested in reading more?

The Scientist ARCHIVED CONTENT

ACCESS MORE THAN 30,000 ARTICLES ACROSS MANY TOPICS AND DISCIPLINES

Become a Member of

Receive full access to more than 35 years of archived stories, digital editions of The Scientist Magazine, and much more!
Already a member?