COLOUR MORPHS OF TIGERS &
POSSIBLE GENE COMBINATIONS

In the Long Island ocelot Club newsletter 23/2 April 1979, Pat Warren wrote "The Color Genetics of Hybrids" based on her F1 Geoffroy's Cat hybrids and F1 Leopard Cat hybrid. Warren considered the rare "blue tiger", by which she meant the grey-striped white tiger which was not yet common in captivity, might be a wild version of the domestic black-to-blue dilution since a tiger's stripes are normally black. Other authorities believed it was due to the coloupoint gene. The colouration is now known to be similar to the colour inhibitor (chinchilla) gene.

In May 2013, a paper published by a team of Chinese scientists including Dr Shu-Jin Luo of Beijing University, in Current Biology, revealed the genetic basis of white tigers. The team mapped the genes of a family of 16 tigers housed at Chimelong Safari Park. These included both normal and white tigers. They discovered that the white coat colouration is due to a single amino acid change, A477V, in a particular transporter protein known as SLC45A2 (which mediates pigment production). This change inhibits the synthesis of phaeomelanin (red, orange and yellow pigment) (phaeomelanin), but does not inhibit the synthesis of eumelanin (black and chocolate) which explains why white tigers keep their dark stripes. The team noted that white tigers had existed in the wild until the 1950s as a natural and viable colour morph, not handicapped by their colouration, until their extinction at the hands of hunters. They believe that the white tiger is worthy of conservation and reintroduction into the wild because they are part of the tiger's natural polymorphic genetic diversity. The defects found in zoo specimens are not due to the single amino acid change, but due to the excessive inbreeding that has caused other genes to accumulate in breeding stock.

KNOWN COLOUR MORPHS OF TIGERS

UNCONFIRMED

Snow White

Tawny (orange/normal)

Blue (maltese)

White (black striped)

Golden (Golden Tabby)

Brown or Red (unstriped)

White (grey striped)

Black (melanistic)

White (red striped)

Black (pseudo-melanistic)

 

White (cream striped/ghost striped)

Brown/beige (brown striped)

 

Albino (pink-eyed)

 

POSSIBLE GENE EFFECTS INVOLVED IN WHITE AND GOLDEN TIGERS

Gene:

Phaeomelanin Inhibitor
("Chinchilla")

Red
(non-extension of black gene)

Colour Dilution

Wide Band

Effect:

Turns hair shafts silver/white on background colour areas

Produces reddish pigment instead of black

Fades pigment i.e. black to grey, red to cream

Changes width of colour bands on hair shaft.

White with black stripes

YES

 

 

 

White with grey stripes

YES

 

?

 

White with red/brown stripes

YES

?

 

 

White with cream stripes

YES

?

?

 

White with ghost stripes

YES

?

YES

Snow White

YES

?

?

YES

Golden Tabby

May be carrier

 

YES

Pale Golden Tabby

May be carrier

?

?

YES

Beige + brown stripes

May be carrier

?

?

POSSIBLY

USEFUL GENETIC TERMS

Textual content is licensed under the GFDL.

For more information on the genetics of colour and pattern:
Robinson's Genetics for Cat Breeders & Veterinarians 4th Ed (the current version)
Genetics for Cat Breeders, 3rd Ed by Roy Robinson (earlier version showing some of the historical misunderstandings)
Cat Genetics by A C Jude (1950s cat genetics text; demonstrates the early confusion that chinchilla was a form of albinism)

For more information on genetics, inheritance and gene pools see:
The Pros and Cons of Inbreeding
The Pros and Cons of Cloning

For more information on anomalous colour and pattern forms in big cats see
Karl Shuker's "Mystery Cats of the World" (Robert Hale: London, 1989 - some of the genetics content is outdated)

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