Jerry Coyne & Manyuan Long on the origin of new genes in Drosophila
Jerry Coyne reports on a new paper in Science by Manyuan Long and colleagues on the origin and history of new genes in a large group of Drosophila that have recently had their full genomes sequenced.
Having this much phylogenetic and genomic information allows researchers to estimate the phylogenetic position of the origin of a new gene (566 new genes amongst the group of 12 fully sequenced genomes, actually), and the periods of time in which directional selection, stabilizing selection, or drift were the dominant regime that the new genes were evolving under. In many cases, there is a period of high selection after the origin of the gene, which weakens later – which is just what you would expect if the well-known, standard model for the origin of new genes is correct.
Two additional points are worth mentioning: (1) in some cases (about 30%, 59 out of the 195 they targeted for knockout studies), these new genes have become essential to viability for the species in question – even though they are totally absent in other, basically similar, flies that do just fine without them! This is strong support for the notion that one way “irreducible” systems evolve is by evolving parts that are helpful at first, but later become essential as other parts coadapt to become dependent on them. (2) I’m sure Luskin, Ewert, and other DI people would like to dismiss this as just another case of evolutionists “illegitimately” inferring common ancestry from “mere” sequence similarity, and that “common design” could be the explanation. However, in any other context, these creationists, and virtually any creationists including the young-earthers, would easily say that all of these Drosophila are just different varieties of the Drosophila kind, and that whatever variety exists between them (minor, in the grand scheme of biology) is “merely” “microevolution within the kind!” (And in the Edge of Evolution, Behe clearly puts his estimated “edge” well above the genus level.)
What’s that? Standard boring microevolutionary processes can produce new genes with modified sequences and new functions, which is clearly new information on anyone’s definition, even the creationists’ and even (explicitly so) Michael Behe’s definition? Oh my goodness, someone better call the DI news blog to put out this fire and reassure the faithful!
References
Chen, S., E. Zhang, and M. Long. 2010. New genes in Drosophila quickly become essential. Science 330:1682-1685.
A previous bit of ranting on this topic by me (responding to Luskin’s ridiculous critique of another famous paper by Manyuan Long, entered into evidence in the Kitzmiller case as exhibit P-245, actually: Long et al. (2003), Nature Reviews Genetics, “The origin of new genes” (free online in many places).