Which two alleles in the Yellowbelly series are described as the weakest?

Gravel and Asphalt

The Yellowbelly series contains alleles that exhibit a spectrum of effects on coloration and pattern modification. At the mildest end of this spectrum are the *Gravel* and *Asphalt* alleles. When a snake is homozygous (carries two copies) for either *Gravel* or *Asphalt*, the resulting visual expression is minimal. These genes cause only subtle alterations to the pattern structure and result in slight overall lightening of the coloration compared to a standard wild-type animal. This subtlety means that identifying a snake carrying just one copy of these milder alleles can be exceptionally difficult, as the changes might be easily missed or attributed to environmental influences.