Adaptationomics

 
Jonathan A. Eisen is an evolutionary biologist with a blog called The Tree of Life. He's also one of the authors of a new textbook on evolution published by Cold Spring Harbor Laboratories [A New Textbook on Evolution]. I'm about to order a copy.

I mention this because Eisen is a pluralist. He's as annoyed by adaptationist just-so so stories as I am. Over on the Dennett on Adaptationism thread I'm encountering commenters who question whether there really are modern scientists who believe in the adaptationist program. I can assure you there are. Eisen has discovered some of them in the field of genomics—he didn't have to look very hard—and he decided to label their approach adaptationomics [Adaptationomics Award #1 - Wolbachia DNA sneaking into host genomes]. This is tongue-in-cheek so don't all you adaptationists get your knickers in a knot.

Here's how Jonathan sets up the issue.

For years I have been fighting against the tide on the tendency for people doing genomics work to resort to silly adaptationist arguments for observations. The argument goes something like this. We sequenced a genome (or did some type of genomics). We made an observation of something weird being present (take your pick - it could be a gene order or a gene expression pattern or whatever). We conclude that this observation MUST have an adaptive explanation. We have come up one such adaptive explanation. Therefore this explanation must be correct.

Gould and Lewontin railed against this type of thing many years ago and others have since. Just because something is there does not mean it is adaptive (e.g., it could be neutral or detrimental). And even if something is adaptive, just because you can think of an adaptive explanation does not mean your explanation is correct.

And this is so common in genomics I have decided to invent a new word - Adaptationomics. And I am giving out my first award in this to Jack Warren and colleagues for their recent press release on their new study of lateral transfer in Wolbachia (plus it lets me plug their new study which is pretty ^$%# cool).

Does this sound familiar?

What did the authors say that makes them adaptationists? In order to understand their statement you have to be familiar with their findings. They discovered that the genome of a parasite (Wolbachia) has been integrated into the geonome of their insect host. There are several reasons why this might have happened. It could just be an accident, since these kind of recombinant events occur frequently and most insects don't carry a full complement of their parasite's genome. In other words, it could be junk.

On the other hand, the parasite genome could possibly confer some (unknown) selective advantage on the host. But here's the rub. When the author of the article, Julie Dunning Hotopp, was interviewed for the the Nature News article here's what she said.

You're talking about a significant portion of its DNA that is now from Wolbachia," says Julie Dunning Hotopp, a geneticist at the J. Craig Venter Institute in Rockville, Maryland, who led the study. "There has to be some sort of selection to carry around that much extra DNA."

That's a classic adaptationist statement. The result "must be" explained by natural selection. There are no other options. I agree with Jonathan Eisen, this is a fitting recipient of his new Adaptationomics Award.

Congratulations to Julie Dunning Hotopp.