Genetics are a bit of a hobby of mine, so maybe I can help explain the roan gene. I have a blog that is pretty informative (I think) about color genetics in general too. This is a bit long, but hopefully it is understandable.
First off, you have to understand that there are 3 base coat colors, Black which is dominant, Wild type which is recessive to black, and Red which is recessive to both Black and Wild. All other colors are MODIFIERS. No matter what color the animal is (from white to grey to roan to tan to spotted) his base coat will ALWAYS be Black, Wild or Red.
The roan gene is
incompletely dominant which means that a homozygous animal will present different traits than a heterozygous animal. This happens MOST of the time, but there are other modifier genes which affect the shade of roan so it is possible to have a hetero animal look the same as a homo animal.
A homo roan (RR)will be white
A hetero roan(Rr) will range in shade from almost solid colored to almost white, in some cases they may look white.
And a homo solid colored (rr) will of course be solid colored with no roaning.
Now, if you take a Roan animal (Rr) and breed it to a solid colored animal (rr)
You have a 50% chance of having a roan (Rr)
and a 50% chance of having a solid(rr)
If you take a Roan (Rr) animal and breed it Roan(Rr)
you have a 25% chance of gettig a white (RR)
50% chance of a roan (Rr)
25% chance of a solid (rr)
If you take a roan (Rr) animal and breed it white(RR)
50% chance of white (RR)
50% chance of roan (Rr)
If you take white (RR) and breed it solid (rr)
100% chance of roan.
Now, to get a blue roan instead of a red roan, you have to understand how the Black/Red genes work.
Black is dominant
Red is recessive
If you have homo black (EE) and breed it hetero black (Ee) (carrying red gene)
50% chance of homo black (EE)
50% chance of hetero black (Ee)
Breed a homo black (EE) to a red (ee)
100% chance of hetero black (ee)
Breed a homo black (EE) to homo black
100% chance of homo black (EE)
Breed Hetero black(Ee) to red (ee)
50% chance of hetero black (Ee)
50% chance of red (ee)
Breed hetero black(Ee) to hetero black(Ee)
25% chance of homo black (EE)
50% chance of hetero black (Ee)
25% chance of red (ee)
my blog
http://easygenes.blogspot.com