Skin colour (PMEL) Adder
peer reviewedPMELrecessive
Casillas et al.: " V. berus exhibits a range of dorsal color patterns spanning from zig-zag to complete melanism. However, a unique longitudinal dorsal stripe pattern was recently discovered in the isolated Gossa Island (∼45 km 2 ) population of Norway, where ∼5% of snakes exhibit this distinct pattern instead of the common dorsal zig-zag pattern."
How it inherits
- One copy
- One copy shows nothing at all. The animal looks ordinary and is called a carrier, or “het”.
- Two copies
- Two copies, one from each parent, are needed before it appears.
Skin colour (PMEL) carrier × Skin colour (PMEL) carrier
Four ways the two can meet.
1 in 4het Skin colour (PMEL)
1 in 4het Skin colour (PMEL)
1 in 4Skin colour (PMEL)
1 in 4Normal
- het Skin colour (PMEL)50%
- Skin colour (PMEL)25%
- Normal25%
A pale box is an animal that shows the morph. These are the odds for each egg on its own, not a promise about a clutch.
What this rests on
A peer-reviewed paper identifies the variant behind this morph in the gene PMEL.
- Genome scanning reveals the genetic basis of a color pattern morphotype in an island population of the European adder (Vipera berus). — Genome Biol Evol 2026
- Dorsal stripe polymorphism of Vipera berus in south-east England — The Herpetological Bulletin 2020
What happens if you breed it
Every pairing involving Skin colour (PMEL), worked out gene by gene — including what the clutch can be and anything documented about the animals it produces.