Originally Posted by mulder
from being a bio geek, i know genetics, but i've never bred before. judging by the bowl o' babies, the red eyed cream is dominant and the brown is recessive, so that's a 2:1:1 ratio for babies. call red eyed cream A, and brown b, well, if it's dominant it's capital, if it's recessive its' lower case. so your cream parent is probably AA since there's so many cream babies. if she was Ab, there'd be more of a 50/50 split. I can't draw a gene box or this would be so much easier.....
That would work if rat hair color was dictated by 1 gene... but it is actually dictated by several genes... I can't name them cause I don't know them... lol but the "brown" of the babies is agouti, which is the wild color and dominant. Agouti rats have black eyes, which is also dominant (making red eyes recessive). So, the agouti rat must be A*R* (A=agouti, R=black eyes)
The beige, I'm guessing (from what I saw at the genetics calculator website) is non-agouti red-eyed, making her aarr (a=non-agouti, r=red eyes). If these parents had beige and fawn babies (note that the "beige babies have 2 different tones, making them 2 different colors) and black and agouti babies, then the agouti dad must carry those genes (making him AaRr)
If we combine the parents AaRr x aarr (doing the punnet square... lol) we would get 25% AaRr (agouti), 25% Aarr (fawn.. which would be agouti red-eyed, and the red eye gene dilutes the fur color too), 25% aaRr (black, non-agouti black eyes) and 25% aarr (beige, non-agouti red eyes, again the red eyes diluting the fur from black to beige).
Of course, these 2 are not the only genes in rats... check the page, there's a couple more and the combination of those genes is what makes the color of a rat's coat. (I personally like the C series... a they create a bunch of cool dilutions including siamese and hymalayan)