Quote: I've never heard it called leakage..most refer to it as "holes" Leakage is usually related to pheomelanin (red/gold pigment), not eumelanin. The "holes" in a paint are eumelanin (black pigment).
It still has not been documented as to whether paint is actually dominant white or a new allele of it, but most geneticists think the former. Left too only dominant white, a lot of colour leaks through, particularly pheomelanin, but also eumelanin (and here I am using "leak" in reference to eumelanin
mea culpa), so most dominant white birds also have other genes that help make an entirely white bird: silver, blue, barring, recessive white, etc. And they are selected for lack of other colours showing up. With paints, on the other hand, we are selecting for birds that DO leak spots of black. Or holes, if you will
