It occurs wherever a part of a gene pool is isolated reproductively from the larger gene pool, in any way whatever and for any reason whatever, by removing some genetic potentials and bringing new genetic combinations to phenotypic expression that were suppressed in the parent population with its greater genetic variability.
A couple questions on what is being seen, as included in the section of Faith's post which you quoted and which I have highlighted in bold.
Does the parent population have greater genetic variability and does such a statement even have meaning?
Do newly seen traits result from simply removing some genetic suppression mechanism, and if so, what is that mechanism?
Aslan is not a Tame Lion