... a HUGE amount of the information is contained elsewhere... (email me if you want more info).
Suffice to say, the THEORY is that ultra is a codominant allele to amelanism, double het animals being some sort of 'ultra-amel' in-between (aka ultramel). There's going to be some breeding trials to prove it, but those won't happen till next spring. Suffice to say, all we have are numerous datapoints of clutches where an ultra or an ultramel was bred to an amel or a het amel, with the expected ratio of ultramels to whatever-else resulting.
Again, the THEORY is that we may have found a codominant gene to amel... that gene being ultra. If you want details, email me... (can't post it here, sadly) 
-Kat
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"You keep WHAT in your freezer?"
"Mice. And rats. If that bothers you, I can call them 'cows' instead."