Copyright, 2007
What? Is this a trick question? This sheep's color is white!
Think again!
HInt: Remember there are 4 gene pairs.
Basic Color - brown or black?
Pattern - white, badgerface, mouflon, English blue, grey, solid?
Spotting - spots, no spots
Extension - dominant, not dominant
Answer:
Basic color; UNKNOWN! (B?/B?)
Pattern: WHITE (Awt/A?)
Spotting: UNKNOWN! (S?/S?)
Extension: NOT DOMINANT (E+/E+)
So, we only really know three of the 8 genes. White covers the other pattern genes, so we only know he has one of those. His pattern is turned on, so he's not extension dominant, meaning he has two recessive E+ genes.
What else do we know about this Shetland ram lamb? His sire is
black and has produced brown lambs. His sire is also solid colored.
That doesn't help with basic color since Dad could have contributed either BB
or Bb. It helps with pattern, since Dad has to be Aa/Aa (It's also known that
he's not extension dominant.). It doesn't help with spotting because Dad could
be either SS/SS or SS/Ss. He's never produced spots, so is likely SS/SS. I'll
put him down for a likely SS with a ? because it's not for sure.
So now, we know:
Basic color; UNKNOWN! (B?/B?)
Pattern: WHITE (Awt/Aa)
Spotting: UNKNOWN! (SS?/S?)
Extension: NOT DOMINANT (E+/E+)
How about Mom? She's white, has produced black lambs - no brown lambs, and none with spots. So, let's assume Mom is BB/BB, and SS/SS.
So now we know (actually we're assuming) more:
Basic color; BLACK (BB/BB or BB/Bb)
Pattern: WHITE (Awt/Aa)
Spotting: NO SPOTS (Probable SS/SS)
Extension: NOT DOMINANT (E+/E+)
We could test breed him with a spotted solid moorit (Bb/Bb Aa/Aa Ss/Ss E+/E+). If any lambs have spots, we assumed incorrect and he's actually SS/Ss. If any lambs are brown he's BB/Bb, and not BB/BB. There is no 100% test breeding for BB/BB.