Data from: Unlinked Mendelian inheritance of red and black pigmentation in snakes: implications for Batesian mimicry

Identifying the genetic basis of mimetic signals is critical to
understanding both the origin and dynamics of mimicry over time. For
species not amenable to large laboratory breeding studies, widespread
color polymorphism across natural populations offers a powerful way to
assess the relative likelihood of different genetic systems given observed
phenotypic frequencies. We classified color phenotype for 2,175 ground
snakes (Sonora semiannulata) across the continental United States to
analyze morph ratios and test among competing hypotheses about the genetic
architecture underlying red and black coloration in coral snake mimics. We
found strong support for a two-locus model under simple Mendelian
inheritance, with red and black pigmentation being controlled by separate
loci. We found no evidence of either linkage disequilibrium between loci
or sex linkage. In contrast to Batesian mimicry systems like butterflies
in which all color signal components are linked into a single “supergene,”
our results suggest that the mimetic signal in colubrid snakes can be
disrupted through simple recombination and that color evolution is likely
to involve discrete gains and losses of each signal component. Both
outcomes are likely to contribute to the exponential increase in rates of
color evolution seen in snake mimicry systems over insect systems.