Yellow Many years ago one would occasionally see sable Australian Shepherds, however it is very unlikely that the gene still exists in the breed gene pool today. The sable gene is dominant to the tan trim gene. The gene for this color is separate from the one that produces sable. It is recessive, so any time yellow pups are produced, both parents carry the gene. Yellow Labradors and lemon Pointers are also e-locus yellow, but in those breeds the color is allowed.
Yellow hair is the same color throughout.
Yellow dogs will not have tan trim, no matter whether their parents had it or not. The action of the yellow gene also lightens the tan markings. White markings are not affected. While both sable and yellow are attractive colors, they are disallowed in the Aussie breed standards and with good reason. Both can mask the presence of merle.