Rabbits fully heterozygous at three loci, B b c ch c h S s (B = black, b = brown

Question

Rabbits fully heterozygous at three loci, B b cch ch S s (B = black, b = brown, cch =

chinchilla, ch = Himalayan, S = long fur, s = short fur) are testcrossed and the 200

progeny are tabulated. Assume Himalayan is dominant to chinchilla.

Black, Himalayan long fur 35

Brown, chinchilla long fur 36

Black, Himalayan, short fur 35

Brown, chinchilla, short fur 37

Black, chinchilla, long fur 13

Brown, Himalayan, long fur 14

Black, chinchilla, short fur 13

Brown Himalayan, short fur 17

a.) Which genes are linked? Which gene, if any is not linked to the others?

Explanation / Answer

Here we see that black chinchilla short and black chinchilla long have the same number.Brown himalayan short has 17 while brown himalayan long has 14 which is not much of a difference.Here we see these 4 phenotypes have lower numbers than the rest, this indicates that these are the recombinant phenotypes. As long and short are the same in some cases and do not vary much in others we can say that they assort independently. They do not play a role in the linkage of the other genes. So we can say that brown himalayan and black chinchilla are recombinants which occur rarely as the two genes are linked and cross overs between these genes are rare. If we see the numbers of black himalayan and brown chinchilla we see a high number. This indicates that in most cases these two genes are passed together as a unit to the progeny and are linked. In addition there is not much difference between black himalayan long and black himalayan short. We can see this even in brown chinchilla short and long. The numbers are almost the same as the parental phenotypes. This confirms that black himalayan and brown chinchilla are linked and S assorts independently hope it is clear

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