So is there any chance that I^S has popped up independently in flocks outside of the lab here in the U.S. or elsewhere? Has anyone looked? If it arose once in a study flock then I would not discount the chance of it occurring elsewhere given the number of flocks and the number of years that chickens have been domestically bred.
And just out of curiosity are there breeders or researchers who scan domestic flocks for possible as yet undiscovered color mutations?
it could be possible for another I^S can pop up again.. I always keep my eyes open for mutations on broiler chicks(sold by the thousands here in Nicaraguan´s meat markets) because they breed millions of them each month.