I can't speak as to the place(s) of origin of the various dominant mutants.
You can pretty much assume that any mutant gene originates in one individual. The only way for any mutant gene to rapidly grow percentagewise in a population is for it to have a selective advantage over the normal gene. If the mutant has no selective advantage over normal, its percentage in the population would remain more or less the same over time. Because in each generation, the same percent of mutants and normals would die off before reaching breeding age. With recessive mutant genes, some infiltrate the normal-looking population when hets are produced. This is not true for dominant and codominant mutations.
In the captive population, the price tag provides the selective advantage for various dominant mutants. Because people will work much harder to reproduce a snake when babies gross $1000 each than when babies gross $25 each.
Paul Hollander