Topic: eye color

Eye color gives clues to underlying genetics. I thought I pretty much knew the genetics of the parents here: above is Neo, a tortoiseshell Dad with clear brown eyes; whose genotype I am pretty sure is:
aaBBCcD-ee
and Sydney, a chocolate doe with brownish eyes, pictured below, whose genotype is
aabbCcD-E-:

But wait! They had a litter that came out in surprise format!
4 of the bunnies were white, which is fine:
aaBbcc---e, and 4 of the bunnies were black, which is also fine:
aaBbC-D-Ee. So far, so good. But, as they reached 5 weeks of age all of a sudden I got a clear look at the eye color of the black bunnies:

Fully black bunnies have brown eyes, and the fellow in the front has grey eyes. Grey eyes in a black rabbit can be caused by having an incompletely dominant "C" gene allowing only SOME of the black and yellow pigments possible in a rabbit express themselves.
(To read all about the black and yellow pigments in any given rabbit's genetics, check out this older post)
So, now we are looking at a "chmc" expressing or a "chdc" expression. Which parent is the culprit?
To get ANY white bunnies in a litter BOTH parents have to have a little "c" gene, which leaves them ONLY one spot to have a big "C" gene. So, one of them has eyes that are not as dark brown as they could be. Mama is the culprit, I can assume. She is the ONLY chocolate rabbit in the barn, and I have had no one else to compare her eyes to. Since her coat has stayed pretty dark, I will rule out the chl gene (although I am open to reinterpretation if someone can suggest further information about this!). That leaves chd and chm as possibilities.
The info I have gathered to date tells me that chm will allow light brown eyes and dark fur. Hmmm. Chm is one of those in-between "C" genes that some color genetics texts discount, preferring to use either a chd, or chl in its place.
So, I am still in a quandry, but I have a little more respect for genes that can modify a color's full expression!







It is always a guess what any two rabbit genetic combinations will produce in the way of color. Sometimes the parent's genes are simple and sometimes (most often)they are not. If you are new at the breeding game, you might enjoy playing with probability calculators, which will show you potential color outcomes of any pair of rabbits mated together.