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Is Standard Grey a separate colour?

 

Multiple Colour Factors

 

Standard Grey is NOT really a separate colour. Rather, it is a combination of a number of colour factors that just happen to blend in natural populations to produce grey. This is normally called the "agouti" pattern. In other animals, the agouti pattern is quite often some shade of brown, such as in Wallabies, Mountain Viscachas, Degus, Gerbils, DeerMice, Rabbits, Hares, Deer, Moose, Bison, Beavers, etc. The Standard Grey is neither dominant nor recessive but midway in between: It is best characterized as "neutral"

 

Colour Expression

 

A particular colour arises in a Chin when a specific set of alleles arise via mutation and "over-power" the rest of the colour alleles. [It appears that, in Chins, each colour trait involves a separate set of alleles, although there may be some overlap.] In some cases, possession of a set of a colour alleles for a particular colour on only one half of a chromosome is sufficient to override the Standard Grey ["agouti"] colour: these are the dominant colour traits. In other cases, the alleles for a particular colour trait must be present on both halves of a chromosome to override the Standard Grey: these are the recessive traits.

 

Letter Codes

 

The symbol g can be used to represent Standard Grey. [Often in textbooks, the symbol a is used instead to represent " agouti".] Thus, a Standard Grey Chin would be represented by g-g However, it should more properly be expressed as the combination of all the possible colour traits in their non-expressed condition. More on this later [3 paragraphs below].

 

Capital Letters: Dominant Traits

 

Dominant traits are represented by capital letters with their non-expressed [or neutral] state being represented by lowercase letters. Thus, instead of using W-g Wilson Whites [as well as White Mosaics and Silvers] are more properly expressed as W-w Note that we can't use W-W because the Wilson White trait cannot exist in the homozygous state due to the Lethal Factor. [For your convenience, you can use WM-wm or W*-w* to represent White Mosaics and Silvers. Similarly, WM-WM cannot exist because of the Lethal Factor.] In a similar fashion, the Velvet Trait in Black Velvets would be best represented as BV-bv rather than BV-g Again, the BV-BV condition cannot exist because of another Lethal Factor. Finally, heterozygous Beige should be represented as B-b rather than B-g . B-B is already used for homozygous Beige.

 

Lowercase Letters: Recessive Traits

 

Recessive traits are represented by lowercase letters with the non-expressed state being represented by capital letters. This is the opposite pattern as for dominant traits [and is a source of much confusion]. Thus, heterozygous Violet [aka "Violet Carrier"] is more accurately expressed as v-V [remember, capital V is the non-expressed allele] rather than v-g Homozygous Violet is normally expressed as v-v Similarly, for heterozygous Sapphire [aka "Sapphire Carrier"], s-S is more accurate than s-g Again, s-s is already normally used for homozygous Sapphire. Although Ebony is variously regarded as "weakly dominant" or "cumulatively recessive", lowercase letters are used represent its expressed state. In the heterozygous state, it is more accurately represented as e-E rather than e-g.

 

Precise Long Genotype

 

Each Chin colour is composed of not only the aforementioned expressed alleles but also the non-expressed alleles for all of the other colours. Thus a pure Wilson White would be "expressed White" plus "non-expressed Velvet" , "non-expressed Beige" , "non-expressed Charcoal" , "non-expressed Ebony" , "non-expressed Sapphire" , and "non-expressed Violet"

In symbol form [The key pairing(s) are marked in green], it would be:

Wilson White:     b-b + bv-bv + W-w + C-C + E-E + S-S + V-V

Using a similar logic for the other colours, we get:

Black Velvet: b-b + BV-bv + w-w + C-C + E-E + S-S + V-V
homo Beige: B-B + bv-bv + w-w + C-C + E-E + S-S + V-V
hetero Beige: B-b + bv-bv + w-w + C-C + E-E + S-S + V-V
homo Charcoal: b-b + bv-bv + w-w + c-c + E-E + S-S + V-V
hetero Charcoal: b-b + bv-bv + w-w + c-C + E-E + S-S + V-V
homo Ebony: b-b + bv-bv + w-w + C-C + e-e + S-S + V-V
hetero Ebony: b-b + bv-bv + w-w + C-C + e-E + S-S + V-V
homo Sapphire: b-b + bv-bv + w-w + C-C + E-E + s-s + V-V
hetero Sapphire: b-b + bv-bv + w-w + C-C + E-E + s-S + V-V
homo Violet: b-b + bv-bv + w-w + C-C + E-E + S-S + v-v
hetero Violet: b-b + bv-bv + w-w + C-C + E-E + S-S + v-V
Pink White [hetero Beige]: B-b + bv-bv + W-w + C-C + E-E + S-S + V-V
Pink White [homo Beige]: B-B + bv-bv + W-w + C-C + E-E + S-S + V-V
Brown Velvet/TOV Beige [homo Beige]: B-B + BV-bv + w-w + C-C + E-E + S-S + V-V
Brown Velvet/TOV Beige [hetero Beige]: B-b + BV-bv + w-w + C-C + E-E + S-S + V-V
Black White Cross: b-b + BV-bv + W-w + C-C + E-E + S-S + V-V
Tan: B-b + bv-bv + w-w + C-C + e-E + S-S + V-V
Pastel: B-B + bv-bv + w-w + C-C + e-E + S-S + V-V
Chocolate [hetero Beige]: B-b + bv-bv + w-w + C-C + e-e + S-S + V-V
Chocolate [homo Beige]: B-B + bv-bv + w-w + C-C + e-e + S-S + V-V
Wilson White Violet Cross: b-b + bv-bv + W-w + C-C + E-E + S-S + v-v
Wilson White Violet Carrier: b-b + bv-bv + W-w + C-C + E-E + S-S + v-V

Finally, Standard Grey will be the combination of all of the non-expressed colour states:

Standard Grey:     b-b + bv-bv + w-w + C-C + E-E + S-S + V-V

More symbol pairings would be added as more colour factors and traits are discovered. A more complete genotype chart can be seen in the Chin Genotype Chart

 

Common Geneotype

 

Each of the 7 symbols [or colour traits] are passed along independently of each other to the sperm/ovum, and hence, to the offspring, If one were to compute all of the possible permutations of a Wilson White X heterozygous Violet mating, this would work out to 49 possible combinations. However, all but 3 will be the same and code for Standard Grey. The remaining three would code for Wilson White, Violet Carrier, and Wilson White Violet Carrier. Figuring this out via Punnett Squares using all of the colour symbols would be formidible. Furthermore, frequent usage of such long sequences of symbols is somewhat cumbersome.

Instead, one can merely use the symbol pair g-g to represent the Standard Grey state. Thus:

     g-g = b-b + bv-bv + w-w + C-C + E-E + S-S + V-V

Since only one half of each chromosome or DNA string is present in a sperm/ovum cell, the single letter g would be:

     g = b + bv + w + C + E + S + V

So, when W-g is used for a Wilson White, the " W could be shorthand for b + bv + W + C + E + S + V [with W being the only expressed alllele] , and g would then be shorthand for b + bv + w + C + E + S + V all of the non-expressed alleles.

Similarly, when v-g is used for a Violet, the " v means b + bv + w + C + E + S + v and g means b + bv + w + C + E + S + V

In this situation, a single Punnett Square will suffice to distinguish all of the possibilities. Hence

  Violet Carrier
Wilson White   X   v g
W W,v W,g
g v,g g,g

 

Precise Short Genotype

 

If one wanted to take a more precise approach to Punnett Squares, for a Chin with just one colour trait, one would focus on only the relevant colour alleles [both expressed and non-expressed versions] and simply ignore all of the other colour traits that are not expressed anyways. For a Wilson White, one can simply use a lowercase w is represent the non-expressed colour allele. Thus, a Wilson White is more properly represented as W-w [short for b-b + bv-bv + W-w + C-C + E-E + S-S + V-V ] rather than W-g Similarly, a heterozygous Violet is better represented by v-V instead of v-g [Remember, capital V is the non-expressed Violet allele.] Thus, in a Punnett Square:

  Violet Carrier
Wilson White   X   v V
W W,v W,V
w w,v w,V

The shortform combinations will translate into the following offspring:
     W-v => W-w + v-v => Wilson White Violet Carrier
W-V => W-w + V-V => Wilson White
w-v => w-w + v-v => heterozygous Violet
w-V => w-w + V-V => Standard Grey

Confusing, eh? One would need to keep the aforementioned long symbol sequences handy in order to decode the short forms.

Well, as long as this distinction is remembered, one can simply use g for expediency and simplicity to represent the non-expressed allele of a particular colour trait in Punnett Squares. Afterall, for recessive traits such as Violet, many get confused trying to remember that a lowercase v and a capital V are the expressed and non-expressed states/alleles, respectively, for the Violet Colour trait. Thus, these are equivalent Punnett Squares:

  Violet Carrier
Wilson White   X   v V
W W,v W,V
w w,v w,V
                    
  Violet Carrier
Wilson White   X   v g
W W,v W,g
g v,g g-g

[A Punnett Square using all of the long symbol sequences can be created as well but it would just be a kaleidoscope of letters to many!]

Which is easier to understand and use? Well, the choice is yours!


 
Alleleic Codes:
  g = Standard Grey
BV = Black Velvet
W = Wilson White
W* = White Mosaic
B = Tower Beige
c = Charcoal
e = Ebony
s = Sapphire
v = Violet
a = Albino



 
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