Glen of Imaal Terrier: Coat Colours

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This page looks at Glen colours and offers a very simple explanation of basic colour inheritance.
Colour Blue, brindle and wheaten (all shades). The Kennel Club Standard (UK)
Color Wheaten, blue or brindle. Wheaten includes all shades from cream to red-wheaten. Blue may range from silver to deepest slate, but not black. Brindle may be any shades but is most commonly seen as blue brindle, a mixture of dark blue, light blue, and tan hairs in any combination or proportion. Official Standard for the Glen of Imaal Terrier (USA)
Please visit the Gallery pages and the Championship Shows pages to see photos of Glens illustrating the range of colours. The Archive page has links to more photos from previous years.
Please click on the links below, or scroll down the page, for information about colour inheritance:
INHERITANCE	DIAGRAM	TABLE	OUR GLENS

COLOUR INHERITANCE

This page offers a very simple explanation of colour inheritance in Glens i.e. why wheaten to wheaten always produces wheaten, but brindle to brindle can produce both brindle and wheaten; and why some brindle to wheaten matings will always produce brindle puppies, but other brindle to wheaten matings can produce both brindle and wheaten puppies!

For the purposes of this explanation:

E is the brindle colour (including the colour variations of blue and blue-brindle)
Brindle is dominant to wheaten in Glens i.e. only one parent need pass on the blue colour for the dog to be brindle.

e is the wheaten colour
Wheaten is recessive to brindle in Glens i.e. both parents must pass on the wheaten colour for the dog to be wheaten.

The dominant colour is denoted with a capital letter, in this case E; and the recessive colour is then denoted with the same letter, but in lower case. The "dominant" letter goes before the "recessive" letter e.g. Ee represents (heterozygous) brindle i.e. the (dominant) brindle colour (E) from one parent and the (recessive) wheaten colour (e) from the other parent.

Brindle (EE)
Brindle (E) colour from both parents (homozygous)
~ will always be a brindle colour
~ will always produce brindle pups

Brindle (Ee)
Brindle (E) colour from one parent and wheaten (e) colour from the other (heterozygous)
~ will always be a brindle colour because the brindle colour is dominant to the wheaten colour

Wheaten (ee)
Wheaten (e) colour from both parents (homozygous)
~ wheaten (e) colour is recessive to brindle (E) colour
~ therefore, wheaten colour can only occur when the wheaten colour is inherited from both parents

INHERITANCE DIAGRAM

This diagram explains how to work out the "colour outcomes" of two heterozygous brindle Glens.

The E gene from parent one and the E gene from parent two		will produce an EE (brindle) puppy
The E gene from parent one and the e gene from parent two		will produce an Ee (brindle) puppy
The e gene from parent one and the E gene from parent two		will produce an Ee (brindle) puppy
The e gene from parent one and the e gene from parent two		will produce an ee (wheaten) puppy

COLOURS TABLE

This table shows the outcomes from the different "colour combinations" of wheaten and brindle variations in the Glen.

Parents			Progeny (Offspring)
A ~ Two homozygous brindles	x	=		will produce all brindle progeny
B ~ A homozygous and a heterozygous brindle	x	=		will produce all brindle progeny
C ~ A homozygous brindle and a wheaten	x	=		will produce all brindle progeny
D ~ Two heterozygous brindles	x	=		can produce both brindle and wheaten progeny
E ~ A heterozygous brindle and a wheaten	x	=		can produce both brindle and wheaten progeny
F ~ Two wheatens	x	=		will produce all wheaten progeny

If two brindles produce wheaten puppies, then both parents will be heterozygous brindle i.e. Ee genotype ~ see line D in table above.

If a brindle and a wheaten produce wheaten puppies, then the brindle parent will have the heterozygous brindle i.e. Ee genotype ~ see line E in table above.

If a brindle Glen has a wheaten parent, then it will have the Ee genotype ~ see lines C and E, and the middle Glen (Breege) in "Our Glens' Colours" (below).

OUR GLENS' COLOURS
I can work out the (very basic) colour genotype of my first two Glens, but not the third!
PHENOTYPE:	The "expressed" trait e.g. the Glen colours of wheaten and brindle (and the variations of brindle).
GENOTYPE:	The "genetic makeup" e.g. EE, Ee and ee

	PARENTS		LITTER SIBLINGS	PHENOTYPE	GENOTYPE

	Sire:	Wheaten ee genotype	All wheaten All ee genotype	Wheaten	ee
	Dam:	Wheaten ee genotype

	Sire:	Brindle Unknown genotype ~ from two brindle parents*	All brindles & blue-brindles All Ee genotype ~ inherited wheaten (e) gene from dam**	Brindle	Ee**
	Dam:	Wheaten ee genotype

	Sire:	Brindle Unknown genotype*	All brindles & blue-brindles Unknown genotype*	Brindle	Unknown*
	Dam:	Brindle Ee genotype**
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