To their surprise, Khila and Abouheif discovered that "evolution has tinkered with the molecular signals that are used by the egg to determine what's going to be the head and what's going to be the tail, to stop the worker ants from producing viable offspring," Abouheif explained. "Different species of ants have different levels of this "reproductive constraint," and we believe those levels provide a measure of how eusocial the colony is. The less the workers reproduce, the more coherent the group becomes."
The existence of sterile castes of ants tormented Charles Darwin as he was formulating his Theory of Natural Selection, and he described them as the "one special difficulty, which at first appeared to me insuperable, and actually fatal to my theory." If adaptive evolution unfolds by differential survival of individuals, how can individuals incapable of passing on their genes possibly evolve and persist?
Darwin proposed that in the case of ant societies natural selection applies not only to the individual, because the individual would never benefit by cutting its own reproduction, but also to the family or group. This study supports Darwin's prescient ideas, and provides a molecular measure of how an entire colony can be viewed as a single or "superorganism."
|Contact: Mark Shainblum|