Tuesday, October 10, 2006

What has Evo-Devo ever done for us? (II)

This discussion reminds me of a conversation I witnessed a few years ago between a population geneticist (PG) and an evolutionary developmental biologist (EDB) that shall remain nameless.

The EDB was explaining to the PG the significance of a paper that had made the cover of Nature a few years earlier. Those who are familiar with the literature on butterfly eyespots know that this is a classic of the field. It's beautifully written and illustrated. I know of more than one biologist that was turned on to the field of Evo-Devo by reading this paper. It shows how the expression of the regulatory gene Distal-less (better known for its role in limb development in Drosophila) is crucial to the formation of the eyespots of the wing of the African butterfly Bicyclus anynana. They analyse mutants, selection lines and different species to come up with a general hypothesis for how eyespot size and shape evolves in these butterflies. It has been cited 143 times and has sparked an entire research program in Evo-Devo.

The problem was that the PG didn't get what all the fuss was about. The EDB was getting more and more excited in trying to convey the beauty and elegance of the results, and he did so eloquently. At some point the PG said something like: "Of course I knew that some genes were involved. Is it really that important that we now know the identity of one of them?"

I think this exchange illustrates well the attitude of biologists for which the ultimate goal of evolutionary biology is not uncovering the precise steps involved in the evolution of a particular structure, but understanding the general evolutionary processes involved. Of course, evolutionary biology needs both.