Here we have the first known dominant mutation in Leopard geckos, and a very exciting mutation indeed! Discovered by Mark & Kim Bell, prodigious reptiles breeders indeed, and initially marketed and named by Kelli Hammack in 2005.
Specimens exhibiting this trait develop spots and patches of coloration in unusual locations, yielding a "calico" appearance as adults. The specimen illustrated here is a juvenile and will develop more of this coloration as it matures. Between the unusual appearance and the unusual dominant mode of inheritance, the exact nature of these geckos was initially something of a mystery, or enigma, hence the name.
Since the mode of inheritance of dominant mutations is new to most Leopard Gecko keepers, I'll attempt to explain it here in some detail.
With regard to the Enigma mutation and it's effect on appearance, Leopard Geckos can exists in three possible genetic states: Normal (no mutated alleles present), Enigma (one mutated allele present) and Enigma (two mutated alleles present).
1) Normal specimens (no mutated alleles present), are of course, just that - completely normal in every way. They exhibit no characteristics of the Enigma mutation, nor can they be heterozygous for Mack Snow. In the above photo, a normal specimen is at top.
2) Enigma specimens (one mutated allele present) can be easily distinguished as hatchlings by their lighter overall appearance, and quickly develop the beginnings of the spots and blotches typical of adults. Strictly speaking, these are in fact heterozygous and typical rules of inheritance apply when breeding them - the only thing different here is that such heterozygous specimens can now be spotted visually, something that cannot be done with simple recessive mutations!
3) Enigma specimens (two mutated alleles present) are suspected to be of identical appearance, as no obviously different specimens have appeared from breedings between two Enigmas thus far. As of this writing, it is unclear whether specimens know homozygous for this trait exist as breeding trials will be required to identify them and clarify this issue.
Understand the mode of inheritance and the predicted outcomes of various crosses can greatly simplify sorting out the results. Perhaps the following will help and is based on the presumption that Enigma specimens possessing two mutated alleles will not differ in appearance from those possessing a single mutated allele.:
Normal x Normal yields all Normal offspring.
Normal x Enigma (one mutated allele present) yields half Normal, half Enigma (one mutated allele present) offspring.
Normal x Enigma (two mutated alleles present) yields all Enigma (one mutated allele present) offspring.
Enigma (one mutated allele present) x Enigma (one mutated allele present) yields 1/4 Normal, 1/2 Enigma (one mutated allele present), 1/4 Enigma (two mutated alleles present) offspring.
Enigma (one mutated allele present) x Enigma (two mutated alleles present) yields 1/2 Enigma (one mutated allele present), 1/2 Enigma (two mutated alleles present) offspring.
Enigma (two mutated alleles present) x Enigma (two mutated alleles present) yields all Enigma (two mutated alleles present) offspring.
