Researchers have discovered that in certain competitive situations, the “fittest” phenotype is the one that is “rarest” for a given population. In a study of fruit flies, when “rovers” and “sitters” were foraging together, “rovers” did better if they were surrounded by “sitters”, and vice versa. As the author of the study put it: “If you’re a rover surrounded by many sitters, then the sitters are going to use up that patch and you’re going to do better by moving out into a new patch. So you’ll have an advantage because you’re not competing with the sitters who stay close to the initial resource. On the other hand, if you’re a sitter and you’re mostly with rovers, the rovers are going to move out and you’ll be left on the patch to feed without competition.”
She also said: “There’s considerable genetic variation in nature and we haven’t been able to explain why it persists, since natural selection ensures that only the best survive.” So, which is the best, the “rover” or the “sitter”? Well, as Mark Fitzpatrick, a doctoral student involved in the study, states: “In the case of fruit flies, one variant encourages the survival of the other. In essence, there is not one best type of fly.”
I know there are population geneticists out there, so, if you can, how would you explain NS being able to virtually decide that it is “best” to conserve both forms, rather than to single out one of the two forms? Or, does this mean that there really is no such thing as “fixation” and “extinction”, thus rendering neo-Darwinism null and void?