I was mistaken. No mutant shrimp were produced. Alan Gishlick of the National Center for Science Education (NCSE) was quick to point this out, calling my statements "thinly disguised creationist pontifications."
In fact, I made the mistake because I gave the UCSD researchers more credit than they deserved. Their actual results provide even less evidence for evolution than I was initially led to believe.
On February 5, a reporter from ABC.com called and asked me to comment on a UCSD press release that claimed: "Using laboratory fruit flies and a crustacean known as Artemia, or brine shrimp, the scientists showed how modifications in the Hox gene Ubx — which suppresses 100 percent of the limb development in the thoracic region of fruit flies, but only 15 percent in Artemia — would have allowed the crustacean-like ancestors of Artemia, with limbs on every segment, to lose their hind legs and diverge 400 million years ago into the six-legged insects."
William McGinnis, who led the UCSD research team, was quoted as saying that "during the early evolution of insects, this gene [i.e., Ubx] and the protein it encoded changed so that they now turned off those genes required to make legs, essentially removing those legs from what would be the abdomen in insects."
Based on the wording of the press release and McGinnis’s matter-of-fact statement, I assumed that the UCSD scientists had produced a mutant shrimp without hind legs. I then argued that this would not justify the researchers’ claim to have discovered a "general mechanism for producing major leaps in evolutionary change," since it takes a lot more to turn a shrimp into a fruit fly than eliminating a few legs.
Once I read the Nature paper (which was not made available until the day after the press release), I realized that the UCSD researchers had actually put a shrimp protein into a fruit fly embryo. A comparable protein from the fruit fly’s abdomen would have suppressed limb development in the embryo’s thorax (chest) region, but the shrimp protein permitted embryonic limb rudiments to form.
So the UCSD researchers did not produce a mutant shrimp. Apparently, they didn’t even produce a mutant fruit fly — they merely showed that a shrimp protein enabled a fruit fly embryo to form leg rudiments where they would have formed normally. The results are interesting, but they fall far short of demonstrating how an aquatic crustacean might have evolved into a terrestrial insect.
Gishlick and other defenders of Darwinian evolution should take no comfort from my mistake. In light of the UCSD researchers’ actual results, their claim to have discovered a "general mechanism for producing major leaps in evolutionary change" is even more exaggerated than I originally thought.
"Shrimp is the fruit of the sea. You kin barbecue it, boil it, broil it, bake it, sauté it, - but you cain't turn it into a fruit fly."
- with apologies to Bubba in "Forrest Gump"