Sunday, November 26, 2006

Astanax Mexicanus

This excerpt from Science News:

Did Cavefish trade eyes for Good Taste? A certain cavefish seems to have thrown away its eyes for a bigger jaw and a more sensitive palate. The cave fish {Astanax Mexicanus, hereafter A.M.) in Mexico (according to William R Jeffrey of University of maryland: College Park). Its seeming ancestor is a terrestrial dweller. The A. M. has eyes as an embryo, but quickly degenerate. The bigger jaws, more teeth sort of push out the eyes, but the nervous system is enhanced in the taste buds. A special protein drives eye degeneration in cave fish and also enhances the jaw and taste bud enhancements. The enzyme - or lack of it - modifies both A.M. and its surface dwelling ancestor. It seems that to survive, the enzyme was selected so that the cave fish can more appropriately detect its food supply.

Lamark might have found this interesting. In this case, it appears that Darwin and Lamark are both needed to make the case of this evolutionary pathway.

No comments: