Basic Color Genetics

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Basic Color Genetics[edit | edit source]

This page covers the five base alleles that affect the coat color of domestic rabbits. This article focuses strictly on genotype (the genetic makeup), not phenotype (how the color appears).

  • Genotype* = the black-and-white formula on the gene that produces a color.
  • Phenotype* = the observable color, often used in breed standards.

Understanding genotype is crucial for predicting offspring color in breeding.

A – Agouti[edit | edit source]

The Agouti gene has three alleles:

  • A – Agouti (most dominant)
  • at – Tan
  • a – Self (most recessive)

The Agouti locus expresses the “wild color” banding along each hair shaft. Agouti hairs have alternating bands of eumelanin (dark pigment) and pheomelanin (yellow/red), producing a “ringed” appearance. Standard Agouti colors include Chestnut (Castor), Sandy, Copper, and Chinchilla (Squirrel). Other Agouti-based patterns modified by additional genes include Red, Steel, Harlequin, and Ermine.

  • Tan (at) – Eumelanin on top, pheomelanin on the bottom; expressed across the back, ears, face, belly, and inside the ears. Dominant over a (Self), recessive to A. Examples: Tan, Marten, Otter.
  • Self (aa) – Requires homozygous recessive alleles. Produces solid-colored hair shafts, typically expressing the base color at the B locus and sometimes modified by the D and E loci. Examples: Black, Chocolate, Lilac, Blue, Tort.

Summary Table:

  • A = Agouti (banded hair shaft)
  • at = Tan (solid color on top, pheomelanin on bottom)
  • aa = Self (solid hair shaft)

B – Base Color[edit | edit source]

B Locus

The B locus controls the type of eumelanin expressed:

  • B – Black (dominant)
  • b – Brown/Chocolate (recessive)

Base color forms the foundation for many rabbit colors (e.g., Black, Chestnut, Chinchilla, Harlequin, Torts) and can be masked by other genes (white or pheomelanin-only expression).

C – Color Coverage[edit | edit source]

C Locus

The C locus affects color intensity and coverage. Four primary alleles:

  • C – Full Color (dominant). Expresses complete eumelanin over the body; modified by at, d, e, and En loci. Examples: Solid Blacks, Chocolates, Blues, Lilacs, Chestnuts, Steels, Harlequins.
  • chd – Dark Chinchilla. Strips most pheomelanin while leaving eumelanin intact; affects Agouti most. Produces Martin, Fox, Ermine, Chinchilla, Silver-Tipped Steel, Magpies.
  • chl – Light Chinchilla. Co-dominant; partially strips pheomelanin. Agouti rabbits with chl- are Siamese; self and tan rabbits with chl- are Sable. Homozygous chlchl = Seal.
  • ch – Himalayan / Californian. Temperature-sensitive; color restricted to cooler points (ears, nose, feet, tail). Recessive to C, chd, chl; dominant over c.
  • c – Albino. Most recessive; masks all other loci when homozygous (cc), producing red-eyed white rabbits.

D – Density[edit | edit source]

D Locus

The D locus controls pigment density:

  • D – Full Density (dominant)
  • d – Dilute (recessive)

Dilution affects eumelanin: Black → Blue, Chocolate → Lilac. Think of it as a “brightness slider” for color intensity.

E – Extension[edit | edit source]

E Locus

The E locus controls how far color extends along the hair shaft in Agouti rabbits:

  • Ed – Dominant Black. Extends B locus color across entire hair.
  • Es – Steel. Extends B color most of the way; tips show pheomelanin.
  • E – Regular Extension. Normal banding along hair shaft.
  • ej – Japanese / Harlequin. Co-dominant; alternating patches of color.
  • ee – Non-Extension / Tort. Suppresses eumelanin; tips colored, rest pheomelanin.
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