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:
and Sydney, a chocolate doe with brownish eyes, pictured below, whose genotype is
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!