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Author Topic : Quick Colour Genetics Course
 gaylanstudio
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11/19/2011 9:36:55 PM reply with quote send message to gaylanstudio Object to Post   

this post has been edited 1 time(s)

I did a similar document some time ago but it seems to have been lost, so I re-wrote it. I hope that it is helpful to those pursuing a colour project of some type.
-----------------------------
The American Cocker ShowDog Colour Genetic Model:

Part I:

A quickie genetics course:

American Cocker colours in ShowDog are a bit complex. There are 6 loci involved - A, B, C, E, K, and S. The American Cocker has included the K Locus which makes it somewhat more complicated than the English Cocker. In reality the colours of the two breeds are pretty much the same although the frequency of occurrence of certain colours is different.

I will occasionally use some terms in a generic manner which may seem somewhat ambiguous, so to clarify, “dark” means black or brown, “solid” means without significant white – the opposite of “parti”, and “self” means one colour without tan-point or sable markings or shadings. A “self” coloured dog may or may not be parti-coloured – i.e. a black and white particolour is a “self” coloured parti; a black white and tan is a tan-pointed parti; a red and white is a “self” coloured parti; a red tri-colour is a (red) tan-pointed parti and a red bi-colour is a (red) tan-pointed solid.

The American Cocker model actually includes two different types of “self” colour, one of which is largely recessive and the other which is dominant. I will refer to these as “recessive-self” and “dominant-self”.

The term Locus (Loci is the plural form) simply refers to a particular spot in the DNA chain. The individual genes occur in pairs - one comes from the sire, the other from the dam. Depending on the locus there are (in the AC world of ShowDog) two or three possible forms of each gene - these forms are called "alleles".

Many, in fact most of the loci have interconnecting influences where the state of one loci will influence the expression of another loci, masking its effect or preventing its expression. This is where a multi-coloured breed gets very confusing. So, to prepare you for that there will be occasional notes referencing other loci which we have not yet discussed.

The Loci, their Alleles and Order of Dominance:
A – Ay, at, a
B – B, b
C – C, cch, ce
E - E, e
K - Kb, ky
S – S, sp

We use upper case to indicate the more dominant form. When I write "Ay/at", this says that this dog inherited the dominant “Ay” from one parent and the recessive “at” from the other parent.



The A Locus:
The A Locus determines the pattern of the dark pigment - i.e. sable or tan-points or self-coloured.

The possible combinations are “Ay/Ay”, “Ay/at”, “Ay/a”, “at/at”, “at/a” and “a/a”. “Ay” is the sable allele, “at” is the tan-point allele, and “a” is the recessive-self.

“Ay/Ay”, “Ay/at”, and “Ay/a” will all be sable.
“at/at” or “at/a” will be tan-points, including the bi or tri colours (red, buff, or silver).
“a/a” are recessive-self-coloured.

A dog that shows tan-points can not carry sable although it might carry recessive-self. A recessive-self can not carry either tan-points or sable.

NOTE - The actual physical expression of the A locus allele is dependant on both the E and K loci.


The E Locus:
The recessive e on the E Locus lacks the ability to produce dark pigment - black or brown. Therefore a dog that is e/e will be some shade of red-yellow (red, buff, or silver).

A tan-pointed (“at/at” or “at/a”) “e/e” is described as a bi-colour (or tri-colour if it is also a parti). In real life, the tan-point factor is expressed as a lighter shade in the pointed areas, usually described as lighter feathering. I suspect that it would be more obvious in the case of deeper reds and less obvious in paler silvers. In ShowDog we recognize this by labeling these as bi/tri colours. It merely supplies a little additional information as to the underlying genetics of the dog. We do not differentiate a sable or a self in this way – both conditions will be labeled red, buff, or silver, the shade depending on the C locus. On this basis, a red, buff, or silver may produce sable (or self) when bred to a “dark” tan-point dog when the “E” is added.



The K Locus:
The K locus affects how or if the alleles of the A Locus are expressed. The dominant Kb completely overrides the expression of the A Locus – “Kb/Kb” and “KB/ky” will all be self-coloured whether it is black, brown, red, buff, or silver. There will be no visible sable or tan-points.

All tan-point and sable dogs are pure recessive for “ky/ky” (the “y” is for yellow). With self-coloured dogs, it is impossible to distinguish which are dominant-self, due to the presence of “Kb”, and which are recessive-self due to “a/a” and “ky/ky”, and/or “e/e” except through breeding history.



The C Locus:
The C Locus determines the shade of red-yellow. Red (“C”) is dominant; silver (“ce”) is most recessive. “C/C”, “C/cch”, “C/ce” will all be red. “cch/cch” and “cch/ce” will be buff. “ce/ce” will be silver. This locus is only apparent with the recessive “e/e”. (In real life it will affect the tan-points and sable base shade as well as “brown”.)



The B Locus:
The B Locus determines the type of dark pigment. “B/B”, and “B/b” will be black - solid black, black and tan, black and white, black,tan and white. The recessive b/b will dilute the black to brown. “B/b” will be black but can produce brown.

This locus applies to both hair and skin pigment so that a “B/B” or “B/b” will have a black nose, eyerims, etc., while a “b/b” will have brown regardless of their coat colour or pattern. It is recognized in the ShowDog English Cocker descriptions but not the American. In American Cockers the status of this locus is only known in the presence of the dominant “E” with self-colours or tan-points. We are not told if a sable, red, buff, or silver has a brown nose and is thus “b/b”.




The S Locus:
The S Locus determines "White Spotting" - whether the dog is solid or particolour. S is the dominant allele; sp is the recessive and produces the particolour pattern. S/S, and S/sp will both be solid. sp/sp will be particoloured.

The coloured areas of a particolour are determined by the other loci. A “black, white and tan” is really a standard patterned black and tan with white. The appearance of white is totally independent of all the other genes.

 Envisage
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11/27/2011 6:19:44 PM reply with quote send message to Envisage Object to Post

Too bad the dog information page doesn't tell the dog's genetic code on the same line as the sop.
I think it would make all this simpler to understand. I know this is a lot of work for you to write out. I printed it out and plan to take a look closer at it. Although, I'm not sure I'm making very good sense of it.

 gaylanstudio
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11/28/2011 2:26:33 PM reply with quote send message to gaylanstudio Object to Post

If we were given the code, how much fun would colour breeding be, huh!

I've added a Part II and Part III.


Part II:

For simplicity, let’s just look at 3 of the six loci – A, E, and K. We are omitting the genes responsible for changing black to brown, producing particolours, and the three shades of red,buff,silver.

A has 3 alleles - “Ay”, “at”, and “a”.
E has 2 alleles – “E” and “e”.
K has 2 alleles – “Kb” and “ky”
-----------------------
Black - Ay/Ay, E/E, Kb/Kb
Black - Ay/Ay, E/E, Kb/ky
Sable - Ay/Ay, E/E, ky/ky - ky/ky allows the sable to show

Black - Ay/Ay, E/e, Kb/Kb
Black - Ay/Ay, E/e, Kb/ky
Sable - Ay/Ay, E/e, ky/ky - ky/ky allows the sable to show

Red - Ay/Ay, e/e, Kb/Kb - e/e prevents dark pigment (sable) from showing
Red - Ay/Ay, e/e, Kb/ky
Red - Ay/Ay, e/e, ky/ky
------------------------
Black – at/at, E/E, Kb/Kb
Black – at/at, E/E, Kb/ky
Black/Tan – at/at, E/E, ky/ky - ky/ky allows tan points to show

Black – at/at, E/e, Kb/Kb
Black – at/at, E/e, Kb/ky
Black/Tan – at/at, E/e, ky/ky - ky/ky allows tan points to show

Red – at/at, e/e, Kb/Kb - e/e prevents dark pigment, Kb prevents tan point pattern
Red – at/at, e/e, Kb/ky
Red/Tan – at/at, e/e, ky/ky - e/e prevents dark pigment, ky/ky allows tan point pattern
------------------------
Black – a/a, E/E, Kb/Kb - dominant (Kb) and recessive (a/a) self colours are present here
Black – a/a, E/E, Kb/ky - both dominant and recessive self are present here
Black – a/a, E/E, ky/ky - only the recessive self is present here

Black – a/a, E/e, Kb/Kb - both dominant and recessive self are present here
Black – a/a, E/e, Kb/ky - both dominant and recessive self are present here
Black – a/a, E/e, ky/ky - only the recessive self is present here

Red – a/a, e/e, Kb/Kb - both dominant and recessive self are present here
Red – a/a, e/e, Kb/ky - both dominant and recessive self are present here
Red – a/a, e/e, ky/ky - only the recessive self is present here
-------------------------
Part III

Perhaps the little game I presented in the English Cocker forum might help. The American version is a little more complex due to the interactions but give this a try:

You need two coloured pens, pencils, crayons – one blue (for boys) and one red (or pink for girls), and some stiff paper or light cardboard – file cards works great. You’ll also need a cup or jar and a sheet of paper to record the results..

Cut 8 equal squares from the cards and divide them into two piles of 4 each. Use the blue pen and write “Ay” on one side of a square and “a” on the other side. On the next square write “E” on one side and “e” on the other side. On the 3rd square write “Kb” and “ky” and on the last one write an “X” on one side and a “Y” on the other. This will be our paper stud and he will be solid self black. Let’s call him “Simon”.

With the red pen write on the second set of 4 squares – “at” and “a”, “E” and “e”, “ky” and “ky”, “X” and “X”. This is our paper broodie and she will be black and tan. Let’s call her “Lucy”.

Simon – black - Ay/a, E/e, Kb/ky, Y/X
Lucy – black&tan - at/a, E/e, ky/ky, X/X

Throw all 8 squares into the cup and shake them up, then dump them out and line them up in alphabetic pairs – you’ll have one of each colour for each letter. (The X’s and Y’s go together – two X’s (one red, one blue) is a girl; a red X and a blue Y is a boy. Surprize!) Don’t turn them over! This is your first paper-puppy. It should look something like one of the combinations at the beginning of this document. Find the match and that’s what colour this puppy will be. Record the results on the sheet of paper.

Dump all the squares back in the cup and have Lucy whelp three more puppies, recording each on the sheet of paper as for the first one.

Potentially you could have black, black and tan, sable, and red in this litter. The bigger the litter (6 or 8 pups) the greater the potential is to see all possible variations. If you wanted to explore this experiment further you could make squares to represent each of the puppies in the first litter and breed them.

You could also add the missing genes for particolour, brown, and buff, silver by cutting another 6 squares. Write “S” on one side “sp” on the other, once in red and once in blue for Lucy and Simon (2 squares) to add the particolour factor. The A, E, and K factors are determined exactly the same as before but if you get a pair of “S” (one red, one blue) or an “S” with an “sp” the colour will not change – they will still be solid whatevers. If you get two “sp” the puppy is a particolour.

If you want to add the brown factor, put a “B” and a “b” in red then blue and add them to Lucy and Simons “genes”. Anywhere that “black” shows up will now be “brown” if you get a pair of “b”.

Since there are three C alleles, you will need to put a “C” with a “ce” in one colour, and a “cch” with a “ce” in the other colour. You will only see the colour change if you otherwise have a red (or red/tan). A “ce/ce” pair will be silver (or silver/tan, or silver bi-colour). A “cch/ce” pair will be buff (buff/tan, buff bi-colour). A “C” with anything will still be red.


 gaylanstudio
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12/27/2011 11:14:55 PM reply with quote send message to gaylanstudio Object to Post

Upsy Daisy!
 willow wood
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1/14/2012 3:35:11 PM reply with quote send message to willow wood Object to Post

So when breeding buff, silver, red.. Does this say red only needs to be on one side? red is dominent over both buff and silver? If all three lines were pure... buff would need to be on both sides of red to be present. Then what of silver? does buff dominate silver in the same way?

If I breed a half silver to a half buff.. then will I only get buff, and of course the colors from the other side?
 gaylanstudio
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1/15/2012 12:55:28 PM reply with quote send message to gaylanstudio Object to Post

I don't know if this will answer your question but assuming we have a group of dogs that are all either red, buff, or silver, including all the variations of bis, tris, and partis (its irrelevant at this point) all of these dogs are going to be "e/e".

Graphically (sort of):
Red Cs/cch bred to Red Cd/ce:
Note - I have added an s and d to identify the "C" from the sire and dam. "Cs" and "Cd" are identical. Is this what you mean by half silver, half buff (the other half is red)?

We have 4 pups. The sire gives a "C" (Cs) to two of them and his "cch" to the other two. The dam also gives her "C" (Cd) to two of the pups and her "ce" to the other two. Now the randomness comes into play.

Sire:
Cs
Cs
cch
cch

Dam:
Cd
Cd
ce
ce

Possible Combinations:

Cs/Cd - will be red "C/C" pure.
Cs/ce - will be red "C/ce" carrying silver.
cch/Cd - will be red "C/cch" carrying buff.
cch/ce - will be buff "cch/ce" carrying silver.

You are not guaranteed to get equal numbers of each of these combinations so actual numbers may vary. The larger the litter (or pup total) the closer you will get to this.

Generally, I believe the short answer to your question, Willow Wood, is yes. To get silver, both parents have to carry silver (or be silver).

-------------
The "C" location determines the shade of "yellow" - one Locus, three variable values, two of these for any one dog.

Silver is at the bottom, recessive to both red and buff. To be silver, the dog must be "ce/ce".

Buff (cch)is in the middle - recessive to red (C) and dominant to silver. A buff dog may be "cch/cch" (pure for buff) or it may be "cch/ce" - buff but carries silver.

A red may be "C/C", pure for red. This dog will produce all red whenever it is bred to buff or siver as he/she will give a "C" to all of it's offspring.

A red may be "C/cch" - red carrying buff.
Bred to a pure buff (cch/cch)
2 C/cch - red/buff
2 cch/cch - buff/buff
Bred to a pure silver (ce/ce)
2 C/ce - red/silver
2 cch/ce - buff/silver
Bred to a buff carrying silver (cch/ce)
1 C/ce - red/silver
1 C/cch - red/buff
1 cch/cch - buff/buff
1 cch/ce - buff/silver

A red may be "C/ce" - red carrying silver.
Bred to a pure buff (cch/cch)
2 C/cch - red/silver
2 cch/ce - buff/silver.
Bred to a silver (ce/ce)
2 C/ce - red/silver
2 ce/ce - silver/silver

Bred to a buff carrying silver (cch/ce)
1 C/cch - red/buff
1 C/ce - red/silver
1 cch/ce - buff/siver
1 ce/ce - silver/silver

 GaylanStudio7
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 gaylanstudio
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Bumpity bump!
 gaylanstudio8
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 gaylanstudio
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To the top! Again . . .
 gaylanstudio8
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 GaylanStudio9
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 gaylanstudio
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 Foxley Cockers
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6/2/2013 2:26:42 PM reply with quote send message to Foxley Cockers Object to Post

Aside from producing color, I've noticed the red gene is powerful. I thought black was the most dominant color, but red is also very dominant. It is also connected to quality. Red wants to dominate the kennel if it can. I think it wants to dominate the entire breed eventually.
 gaylanstudio
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6/2/2013 9:58:34 PM reply with quote send message to gaylanstudio Object to Post

I've thought a number of times that there seems to be some colour-trait linkage, accidental, on purpose, or how I don't know, but not really unrealistic.

Reds are "better" because of the C/C which is/was virtually universal in all the competitive lines when we got colours. The silver (ce) and buff (cch) had to be brought back through source dogs. The recessive e however had disappeared so we did not see the reds and this too had to come from near source.

We found some reds in really old reclaimers and even engaged in resurrections. Yes, a glitch (accidental or on purpose) allowed us to "reclaim" some dead dogs. We had to breed fast and hope the girls stayed alive long enough to give birth. Heady times they were, as close to God-like as any of us have been (lol).



 willow wood
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6/3/2013 9:31:55 AM reply with quote send message to willow wood Object to Post

So were dealing with a strain virtual zombie dogs here that want to dominate the breed... That's very interesting.

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