“Fifty to 100 genes affect whether a worm enters the dauer state. In theory, deletions on any of them could keep worms from becoming dauer larvae. But many of these genes affect several aspects of the animal’s development and physiology, whereas the pheromone receptors simply sense the environment and thus can be lost harmlessly, Bargmann suggests. The study may point to “a general rule,” adds Phillips: that evolution tends to delete genes whose loss will not have widespread effects, an idea that is very slowly gaining ground.”
Interesting. In my head, it’s really about “adjacent possibles”, so in this case, the pheromone receptor was it. Perhaps changes in one of the other 50-100 genes are not an adjacent possible for the phenotype they found. In any case, quite interesting. And I’m sure folks are going to study how complex these changes can be.