Dexters and the Genetics of Leg-Length

It appears that the gene relating to leg length in Dexters has two alleles, one which is dominant and generally designated as "L", the other which is recessive and generally designated as "S". A Dexter with "LL" is long-legged, an "LS" Dexter is short-legged, and an "SS" Dexter is a non-viable bulldog calf. Photos of a bulldog calf (which are rather distressing).

If two long-leg (LL) Dexters are mated, only long-leg (LL) Dexters result - remember, offspring receive half of their DNA from their mother and half from their father:

L L   x   L L 

gives

L L

L L

L L

L L

If a long-leg (LL) Dexter is mated with a short-leg (LS) Dexter, then of the four possible resulting genotypes, two are long-legged (LL) and two are short-legged (LS):

L L   x   L S 

gives         

L L

L S

L L

L S

If two short-leg (LS) Dexters are mated, then of the four possible resulting genotypes, one is long-legged (LL), two are short-legged (LS) and one is a bulldog calf (SS):

L S   x   L S

gives         

L L

L S

S L

S S

Note that these genetic outcomes are statistical probabilities only. For example, the first four calves from the same sire and dam may be all of exactly the same type.

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