Affects Base Coat AND Markings
Usually only visually affects black color, and will not show up in purely red-based markings or coats.
Agouti coats like seal, brown, and bay may have merling anywhere on the base coat due to the presence of at least some black pigment in each hair.
Merle creates "roaned" out patches across the body where black is present, and may also cause white around the chest and feet.
Merle affects dark skin with patches of pink. It may cause blue eyes and heterochromia. The eyes and skin may give away the presence of merle in creatures with otherwise entirely red coats, or very little merle patterning.
In hooved creatures, it may also dilute streaks in the mane and tail.
Double merle, MM, causes extensive pigment loss across the entire body which will cover up other markings just like white spotting genes, and almost always results in deafness, blindness, or both. It also tends to cause smaller than usual eyes.
Almost entirely diluted with some small, slightly less affected, splotches:
Large unaffected patches, with some partially diluted splotches:
Merle is fairly well spread through all the black area, some diluted, some not:
Merle is barely visible, restricted to only a few small diluted areas:
Shows merle only on black saddle area, not red:
Merle on sable, barely visible due to the low black content in the fur:
Double merles, made almost entirely white. White covers red areas too: