Making an example of couch potatoes
Illustration by Beto Alvarez, Inquirer Staff ArtistYesterday the Philadelphia Inquirer profiled an article just published by my lab, which demonstrates the role of a gene called couch potato in determining reproductive diapause in fruit flies. Genes in flies are named after their mutant phenotype; when this gene is disrupted, the animals lie around like lazy couch potatoes.
The nifty thing about this new work is that it demonstrates how a single gene—and more specifically, a single nucleotide site within that gene—affects a major phenotype under strong selection in natural populations. Diapause is a physiological state which permits flies to withstand long periods of stress. Flies are more likely to survive winter if they are in diapause, but not all flies are capable of entering diapause. This paper demonstrates that a single nucleotide polymorphism, which is located within the couch potato gene, determines whether flies are diapause-capable or not. From Florida to Maine, natural populations of fruit flies have gradually increasing frequencies of the nucleotide that confers diapause capability—almost all Maine flies, which must survive long winters, carry the diapause allele. Evidence suggests that this polymorphism affects other traits, like lifespan and reproduction, as well. So it’s likely that this single mutation has significant effects on the evolution of many traits. A tidy example of evolution at work (for those keeping track).
The article was published yesterday in PNAS.