> Brown or Liver/chocolate is different to Red/Yellow genetically
I can put this into simple terms (I hope).
Brown/Liver/Choc are all a mutation on the B (Black) locus which changed black into brown. Genetically it is described as
bb.
Red/Yellow is a mutation on the E locus [I believe E stands for Extension - which depending on the mutation, can be Extension of black, or Extension of yellow. All dogs which are
ee are yellow, but this can vary from cream through to golden, through to red, through to a very deep red which can be mistaken for liver.
I guess it's unfortunate that some colours in some breeds have been called "red" for so long.... renaming them liver or chocolate would help.
However there are three different "types" of Brown/Liver/Choc now mapped by DNA and obviously some of those are so bright and rufous that they are likened to a 'red' even though they are still genetically a Brown, and still part of the brown/black locus B.
A very reddish brown was discovered in cats some years ago - a real bright foxy shade - named Cinnamon, a relative of Chocolate, which is probably analogous to the very reddish brown shades we see in choc/liver dogs.