IMG

What IMG looks like

Heterozygous IMG (Increasing Melanin Gene). Single copy of the IMG allele. Progressive darkening with age. Melanin deposition increases with each shed cycle. Hatchlings may appear normal or slightly enhanced in dark coloration, but adults show notably more melanin coverage than non-IMG animals. Pattern darkens progressively and substantially over 1-3 years.

The IMG (Increasing Melanin Gene) locus is an incomplete dominant trait that progressively increases melanin deposition throughout the animal's life, causing the snake to darken with age. Unlike most morph traits that are fixed at hatching, IMG produces a dynamic phenotype that continues to change over months and years. Three phenotypes exist based on zygosity. Heterozygous IMG (single copy) animals hatch with relatively normal to slightly enhanced dark coloration, but progressively darken with each shed cycle as they age. The dark saddle pattern expands and the light background between saddles becomes increasingly invaded by melanin. Adult het IMG animals may appear significantly darker than non-IMG animals of the same species. Homozygous Super IMG animals show this darkening effect dramatically accelerated and intensified. They may appear nearly solid dark/black as adults, with the pattern almost completely obscured by melanin deposition. IMG is notable for being one of the only boa morphs with a predictably progressive phenotype. It originated from Boa constrictor constrictor (true red-tail boa) lines from South America and may express somewhat differently in BCI vs. BCC genetic backgrounds.

How to identify it: IMG (single copy): Hatchlings may appear relatively normal or slightly enhanced in dark coloration. The key diagnostic feature is progressive darkening with each shed. Observe the animal over 6-12 months. Background coloration between the dark saddles will increasingly become invaded by melanin, making the animal appear darker overall. By adulthood, het IMG boas show notably more melanin coverage than non-IMG animals of the same locality or line. Super IMG (IMG/IMG): Progressive darkening is dramatically accelerated. Young Super IMG animals may already show extensive melanin at 6-12 months, and adults can appear nearly solid dark brown to black with the underlying pattern largely obscured. The progressive nature of the phenotype makes young animals difficult to evaluate. IMG's full expression is best assessed in animals 2+ years old.

How IMG is inherited

IMG follows a incomplete dominant inheritance pattern, carried on the IMG (Increasing Melanin Gene) allele (locus IMG).

Combo morphs with IMG

• IMG Hypo

  IMG Hypo combines the Increasing Melanin Gene with Hypomelanistic. These two traits have opposing effects on melanin. IMG progressively increases melanin deposition while Hypo reduces it. The interaction produces an animal that darkens with age (from IMG) but from a lighter starting point (from Hypo), and the rate and degree of darkening may be modulated by the Hypo background. In some lines this combination is called "True Ghost" by breeders, though that name is not universally standardized. The result is a dynamically changing animal with a unique balance between melanin reduction and progressive melanin increase.