Differential reproductive success

John Tyndall
Somewhere stumbled upon JohnTyndall using DRS, with differential he meant small imperceptible differences adding up to transform a species, like the flow of honey. Will have to find the link again.

He meant by this small differential changes accumulating via PatrickMatthew's natural means of competitive selection(what Darwin actually meant with Natural Selection) and specifically used Survival of the Fittest, which is a restating of Democritus atomism or what HenryFairfieldOsborn referred to as the doctrine of atoms.

A difference or differential could be either large or small, the term itself doesn't provide the scale.