le patrimoine génétique des alpagas gris
...et comment les reproduire
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Greys! Aren’t they fascinating? If you are reading this then I think you and I would agree that they certainly are! As a grey breeder, I felt compelled to further understand the genetic inheritance of colors and patterns. This subject seemed highly relevant to our breeding strategies in ultimately producing greys with a certain level of predictability. The following is meant for new breeders interested in greys or breeders looking to better understand how color and patterns are inherited within his herd.
After talking with some fellow breeders and explaining how I calculate percentage of color and pattern probability, I quickly realized that this topic was actually of interest to most of them as well. They actually seemed interested in knowing more. This is why I felt compelled to share some insights from some of my reads and other theories from hands-on experience breeding greys for almost 10 years.
There are many different patterns and hues of colors out there and some genetic processes of inheritance in alpacas are still not completely understood to this day. Unlike other animals such as horses or dogs which have been widely studied in terms of colors and patterns, researches on alpaca color & patterns are limited at best. More recent studies have unmasked certain underlying genetic processes of inheritance in our beloved alpacas but some of these concepts are often very complex and hard to fully understand for breeders like me who do not have any background in genetic studies. The following is an attempt to simplify or vulgarize if you will, some of those concepts and how I apply them to my breeding program strategies.
After wrapping my head around some of those basic concepts and some more complicated genetic processes, I came up with my own simplified version in order to try to predict color and pattern probabilities within my own herd. By sharing this, I hope to help breeders interested in greys or with a color program understand the basic rules in the inheritance of colors and patterns and ultimately provide them with the knowledge to figure out strategies for their own breeding program.
COLORS, ALLELES, PATTERNS AND MUTATIONS
First and foremost, I should start by saying that we breed for advanced fleece style and true to type conformation. These are the two main categories of criteria we look at when selecting a breeding. As a grey breeder, desired color is never too far behind but is never the first criteria. We want to breed for advanced fleeces and proper confirmation no matter the color. If we have done our homework (and with a bit of luck!) we will yield grey or at least a solid non-grey alpaca capable of doing so while limiting the risk of producing undesireable outcomes in future generations.
COLORS AND ALLELES
So let’s start with the fondamental basics. Genes will dictate what color a cria will be and what pattern he will express. Genes are made up of 2 or more alleles which are passed down from parents. A cria will have inherited a color allele and pattern allele from both sire and dam so that adds up to a total of 2 color alleles and 2 pattern alleles. Now from there, colors and patterns will compete for dominance if they are not the same that is if the cria has received different color or pattern alleles from both sire and dam. The cria will always end up carrying all these colors and patterns in its genetic makeup but will only physically express one of each; one dominant color, one dominant pattern.
To simplify things and for the purpose of this exercise, let’s just narrow it down to 3 colors. White, *Red and Black. White is the most dominant, then comes red and finally black being the less dominant, which we would refer to it as being recessive. A white allele (absence of pigmentation) will almost always dominate a red allele and a black allele (with a few exceptions which I will explain later on). Concretely this means that if a cria inherits a white allele from sire and a red allele from dam, the white allele will dominate the red one and the cria will physically appear white. If it inherits a red allele from sire and a black from dam, the cria will appear *red.
* Red can sometimes be labelled as Yellow in certain studies or articles on color. Red is often associated with the color brown and yellow associated to beige and light fawns. For the purpose of this exercise and to simplify the color labelling process, I have combined all of these under Red which would refer to as an alpaca expressing any colors between beige and dark brown as they are the base color on which rose-grey expresses itself (which we will see below under Patterns and Mutations).
TO SUM UP COLOR ALLELE DOMINANCE:
WHITE DOMINATES RED / WHITE DOMINATES BLACK
RED DOMINATES BLACK
BLACK DOES NOT DOMINATE ANY COLOR (IT IS THE MOST RECESSIVE COLOR)
The interesting thing here is that even though a cria physically expresses the dominant color allele, he still carries the other less dominant, recessive allele in his genetic coding. This means that he or she can still pass on their recessive color allele to their offspring. Isn’t that fascinating! Understanding which recessive color allele is hiding in each of your breeders is powerful knowledge when trying to breed for certain colors.
PATTERNS AND MUTATIONS
Patterns are also interesting to look at as they dictate how colors express themselves and are distributed across the body. In many studies, the classic greys (the white faced ones) will carry a specific pattern often referred to either as Tuxedo greys or Classic greys. In this exercise, we will refer to them as Classic Tuxedo greys just so everyone's ''on the same page'' with terminology. Classic Tuxedo, like other striking patterns such as Appaloosa, Harlequin or Roan, are found on a range of different base color coats. Just as in colors, some patterns are dominant and some are recessive.
The pattern at play with Classic Tuxedo greys is believed to be a mutation of the white spotting allele. This pattern makes their extremities appear white which is typically present in the facial and leg areas. Some Classic Tuxedo greys have whiter extremities, some less; it all depends to what extent the pattern has expressed itself. Here’s the fascinating thing about greys; grey is not an actual color! It is the result of a color fading process involved in the expression of a specific pattern, in occurrence Classic Tuxedo which makes them appear grey. A silver-grey alpaca is genetically black. He has received 2 black alleles; one black allele from sire and one black allele from dam. He has also received the Classic Tuxedo pattern from one of his parents which takes his solid black color and fades it to a beautiful silver-grey. A rose-grey alpaca is genetically red but has also received the Classic Tuxedo pattern allele. The solid red color is now faded to rose-grey with more or less white extremities.
Grey breeders are not just aiming at producing an evolved grey alpaca, they are focusing their breeding program around the expression of a specific pattern allele that actually produces grey!
Summary of Part 1
COLORS, ALLELES, PATTERNS AND MUTATIONS
- For the purpose of this exercise, we will categorize alpacas in 3 color categories; White, Red & Black
- Certain colors & patterns are dominant while others are recessive
- Any given alpaca will only express one dominant color and one dominant pattern
- Any given alpaca will carry a recessive color and pattern he will be able to pass down to his progeny
- Grey is not a color, it is believed to be a mutation of the white spotting allele expressed as a pattern
- The Classic Tuxedo grey pattern can be expressed on a range of base color
predicting colors & PATTERNs
COLOR & PATTERN LEGEND
PATTERN ALLELES COLOR ALLELES
S = Solid A = Appaloosa w = white
T = Classic Tuxedo W = *White Spotting r = red
R = Roan H = Harlequin b = black
*In the following prediction charts, White Spotting is not the same as Classic Tuxedo. White spotting here is a reference to an alpaca of solid color (other than grey) with a distinctive white spot somewhere in its blanket or on its extremities, basically anywhere on its body. This category would include Piebald (Pinto) and other similar non-grey white spotting patterns.
As explained earlier, although an alpaca only physically expresses one color allele and one pattern allele, he will still carry 2 color alleles and 2 pattern alleles in his genes. An alpaca in your herd can be coded with those 2 colors and 2 patterns. How you ask?
Well let’s make up a scenario to further understand. Let’s take a solid colored brown alpaca as an example. He is expressing an S pattern (for Solid) and an r color (for red). His sire was the same brown color and pattern as him and his dam was a solid fawn. Hypothetically, this alpaca has received a second S pattern and a second r color from his dam. He has received an Sr combination from sire and also an Sr from dam. If you combine these two, you get an SSrr. Genetically speaking, this is what your brown alpaca is hypothetically coded with and will be able to pass down to his progeny.
It can be passed down to offspring randomly as 4 separate combinations as follow:
SSrr: SSrr=Sr SSrr=Sr SSrr=Sr SSrr=Sr
Now for the purpose of further understanding this, let’s say this brown alpaca had a solid black dam instead of a solid fawn dam. Black being recessive, a black alpaca has to have received two copies of the black allele in order to express it physically. This would make a solid black alpaca an SSbb.
An alpaca labelled as SSbb (Solid black), can only pass down an Sb combination to its offspring as per this breakdown:
SSbb: SSbb=Sb SSbb=Sb SSbb=Sb SSbb=Sb
Back to our brown alpaca which now has a black dam. This would make this brown alpaca an SSrb (instead of an SSrr) as his black dam could only pass on an Sb combination to her offspring. As the color red dominates black, this alpaca would still appear brown but his genes however would now be masking a black recessive allele for life. You now have yourself a brown alpaca with the capacity of throwing a certain number of black offspring when bred to black!
This would be the revised combinations that this brown alpaca can now passed down:
SSrb: SSrb=Sr SSrb=Sb SSrb=Sr SSrb=Sb
Breeding scenario: Our brown alpaca with a recessive black allele (SSrb) with a solid black alpaca (SSbb). Here’s how to calculate combinations and possibilities for this genetic combination.
As previously seen, the genetic combination possibilities for one alpaca can be broken down into 4. With both a sire and a dam passing on each 4 possibilities. When combining (or multiplying) them up, we are now at 16 possible scenarios or genetic combinations that can be passed down to offspring. In this first rather simple case above, we have 8x SSrb and 8x SSbb out of 16 combinations possible. Hypothetically, this leaves us with a 50% chance of either producing an SSrb, a red alpaca (Beige to brown) or a 50% chance of producing an SSbb, a black alpaca.
Now back to greys! We have already seen how colors can dominate each other and how certain patterns can also appear on an alpaca. Much as in colors, certain patterns are dominant and while others are recessive. It is believed that the Classic Tuxedo pattern of greys would be an incomplete dominant as an alpaca only needs one copy to express the pattern. This would make Classic Tuxedo dominant over a solid color pattern. Roan (Modern Grey) is also believed to be an incomplete dominant where only one copy would be needed to express it. Classic Tuxedo being considered as a dominant pattern is how I apply it in my calculations of predictions.
A Classic Tuxedo silver-grey is genetically an STbb (Solid/Tuxedo/black/black). Every Classic Tuxedo grey also carries a Solid allele (or another recessive pattern allele) and we will see why a bit later. A Classic Tuxedo rose-grey is genetically either an STrr (Solid/Tuxedo/red/red) or an STrb (Solid/Tuxedo/red/black). As previously seen, red dominates black so an alpaca receiving an STrb will express a rose-grey Classic Tuxedo pattern instead of a silver Classic Tuxedo pattern (STbb).
Here’s a breeding scenario involving possibilities with a Classic Tuxedo silver-grey. This example would be with a Light Fawn with a recessive black allele (SSrb) bred to a Classic Tuxedo silver-grey (STbb).
Results are now slightly diluted as we have 4 main genetic scenarios out of 16 possible combinations. This leaves us with a 25% chance for each one. This is a very good outcome for any grey breeder; 50% grey and another 50% of non-grey carrying either a recessive black or a double black. This is the type of breeding we are looking for when breeding to solid non-greys and hoping to produce more blacks or silvers in the subsequent generations!
Summary of Part 2
predicting COLORS & PATTERNs
- The genetic coding of any given alpaca can be broken down into 4 seperate combinations
- A prediction chart is based on 16 possible combinations (4 from Sire & 4 from Dam)
- The Classic Tuxedo pattern in greys is believed to be an incomplete dominant as an alpaca only needs one copy of the Classic Tuxedo pattern to physically express it.
- An alpaca with a Classic Tuxedo pattern & a black base color is described as a silver-grey
- An alpaca with a Classic Tuxedo pattern & a red base color is described as a rose-grey
Classic tuxedo greys & blue Eyed whites
There has been (and still is) some confusion out there that two Classic Tuxedo greys when bred can produce a BEW (Blue Eyed White). In almost 10 years of breeding greys with many grey to grey breedings, we have not yet produced a BEW and have only heard of a few cases in the United States of such incidence. These extremely rare cases might have had some misunderstood underlying genetic cause involving an unknown allele mutation or simply that one of the greys was in fact a solid animal carrying the white spotting allele (not a Classic Tuxedo) and that might have been mistaken for a grey.
Two greys when bred together will NOT yield a BEW and this is the reasoning behind it. Let’s take two Classic Tuxedo silver-greys (STbb) and break it down.
You’ve probably noticed ‘Lethal’ as a 25% chance. It is believed that when a cria receives a double dose of the white spotting mutation involved in the Classic Tuxedo pattern (TTrr, TTrb or TTbb), the pregnancy will naturally slip. Seems like this pattern combination is just not viable on a genetic level. Up to recently, this was only speculation but with the results of a recent genetic study on greys, not one single alpaca has been found to be carrying a double dose of the Classic Tuxedo pattern (TT). All Classic Tuxedo greys studied were carrying only one copy of the grey allele mutation projected to be responsible for this pattern.
Basically a TT embryo will never see the light of day! This only means that the grey dam you bred will probably be receptive again within a cycle or two as the pregnancy has slipped. If the pregnancy holds however this would mean that the cria did NOT receive a TT combination and the percentage of possibilities is bumped up to a 66.7% chance of a Classic silver-grey STbb and a 33.3% chance of a solid black SSbb.
Now that said, a BEW CAN be produced when breeding a Classic Tuxedo grey to a non-grey, solid color alpaca that is carrying the white spotting allele (ex. Piebald). This is the combination to avoid if you do not want to produce a BEW. Here’s an example of a Fawn dam with a white spotting pattern (SWrr) bred to a Classic Tuxedo rose-grey (STrr).
This combination can yield 4 different color/pattern scenarios but you always have a 25% chance of producing a BEW with this type of combination; 1 in 4. To say we haven’t tried this would be a lie! We have tried it once and we were lucky enough to get a beautiful DSG female (the sire was silver and not rose-grey) but we still took a chance that we are not willing to usually take in our breeding program. We won the lottery on this one but it could have gone very differently! We breed only a few select subjects every year (approx. 10 crias) so a BEW would definitely be somewhat disappointing.
This same type of scenario can apply to a Classic grey bred to a white. A white alpaca can actually carry the white spotting allele. You just don’t see a white spot on a white colored alpaca! Breeding grey to white requires strong knowledge of your white alpaca’s genetic background and some analysis of what kind of offspring it has previously produced. A white alpaca that has produced a BEW in the past, produced presence of blue eye specks in one of its solid colored offspring or produced a cria with a white spot when bred to a solid non-grey color (as minimal as that spot can be) would indicate that it might be carrying the white spotting gene. The problems with whites is that you don’t know this for sure until they throw something that confirms the presence of the white spotting gene in their genetic coding.
Breeding grey to white is always a gamble and chances are that you might make great gains by doing so with an evolved white. There is also a 25% chance of yielding a BEW if the white alpaca is carrying the white spotting gene. Some breeders are willing to take that chance. We decided that we would not be willing to do so here in our breeding program.
Here’s an example of a Classic Tuxedo silver bred to a double white color allele with a hidden white spot gene pattern.
Other colors such as a solid red, solid black or even a Classic silver or rose-grey could be produced if the white alpaca is not a double white and carries another hidden color allele such as red or black (SWwr or SWwb).
With this new combination, the results are now highly diluted and less predictable. Most of these scenarios should be undesirable to any grey breeder. A 12.5% chance of yielding a rose-grey does not make up for all the other results that may arise from this type of breeding. Also the chances of producing a BEW is unchanged at 25%. Basically 75% of the results above will more than likely produce an offspring with undesirable color or pattern allele for a grey program and that same offspring will have to be bred with great care to avoid further undesirable outcomes with its own progeny.
Last scenario with a silver-grey to white breeding but this time the white is a solid color and does not carry the white spotting gene pattern. It also carries a recessive red allele.
A 1 in 4 chances of producing a Classic Tuxedo rose-grey is actually decent. The solid colors without the white spotting gene pattern could also be used in a grey program without fear of yielding a BEW. Unsure of the white carrying the Classic Tuxedo gene but that might be the only undesirable scenario as it will yield more whites and might be hard to breed out as Classic Tuxedo would be dominant over solid. My fear with this one would be that this type of alpaca (white carrying Classic Tuxedo) when bred to non-white solid colors might produce those piebald type pattern (Pinto types) or other non-Classic Tuxedo white spotting patterns. Who knows! This is just a theory but as a grey breeder, piebald or any other non-grey white spotting patterns should be considered as undesirable. These patterns will ultimately be hard to breed out and could yield BEW when bred to grey. If a breeder is willing to try this type of breeding, who am I to judge! That white carrying Classic Tuxedo might actually be able to throw the Classic greys. Who knows! That said we prefer a safer approach here and therefore we do not breed white to greys for all of the reasons elaborated above.
Summary of Part 3
classic tuxedo greys & blue eyed whites
- Two Classic Tuxedo greys when bred together will NOT yield a BEW
- Classic greys carry only one copy of the grey allele mutation responsible for the Classic Tuxedo pattern
- A double dose of the white spotting mutation involved in the Classic Tuxedo pattern is believed to be lethal
- A Classic Tuxedo grey bred to a non-grey alpaca carrying the white spotting allele is believed to produce the BEWs with a 1 in 4 chance (25%)
- Classic Tuxedo grey breeding to white alpacas should be avoided for many potential undesirable outcomes in progeny which also includes the possibility of producing BEW.
Out of approximately 30 alpacas produced and verified against this way of predicting color and pattern, only 2 or 3 fell outside the prediction box, meaning that they were nowhere on the radar in terms of color or pattern. This is just an indication that there’s more going on than meets the eye and probably just a confirmation that recessive alleles are at play. When this happens, it is an opportunity to learn and figure out precious information about the dam or sire genetic coding (see Case Studies below). There will always be some unforeseen results and genetic processes we don’t quite understand (for now) but we can certainly minimize those cases when working proactively to become more knowledgeable about our individual breeder's genetic background.
There are such things as dominant black alleles out there and other rare recessive patterns which are not well understood yet but they do exist! If you have a black alpaca that mostly produces black offspring no matter what color it is bred to, you have yourself an alpaca possibly carrying a dominant black allele (Give us a call..we are interested!) Jokes aside, this system of calculating predictions is not full proof and is a vulgarization of a much more complex scientific realm. It is only a small tool to help you navigate the fascinating world of infinite possibilities that is the genetics of color and pattern inheritance in alpacas.
SAti OF ARIYA
Female – Beige - 10 years old
Has produced 6 crias with 4 of them being out of silver-grey males. Expected this female to be a Solid Red (SSrr) with no recessive allele. We had chosen silver sires in order to produce rose-grey progeny or solid reds with a recessive black allele.
Male #2 - LSG
Male #1 - MSG
Cria #1 LRG (when bred to Male #1)
This cria was so exciting! It was our first rose-grey and we definitely hit the mark with this one as this little female has gone on to be one of our highest winning grey up to this day earning multiple Grey Color Championships and many, many first places when entry levels were not met for a Grey CC.
This little female fit perfectly within the prediction box as we had expected a 50/50 chance of getting rose-grey out of this breeding combination.
Cria #2 Pinto (when bred to Male #1 again!)
Our first ever pinto! Although unexpected, a beautiful female with exquisite fleece and great conformation. Definitely out of the prediction box but after a bit of research, it seems that the Classic Tuxedo pattern can sometimes be expressed with some variations. Pinto being one of them!
Now that she is of breeding age, we have opted to breed her to a solid fawn with a recessive black allele as this girl is also carrying a recessive black. Only time will tell if we can breed out this white spotting variation or if the Classic Tuxedo allele is still in there, intact, and she surprises us with a Classic Tuxedo when bred to solid! This will be an interesting case to follow…
Cria #3 White with silver markings (when bred to Male #1 again!)
So this was certainly the most shocking result out of them all! This white female had normal eye color (no blue speck) and a few silver markings; one MSG lining her right ear, one spot behind her left ear and another 4inch LSG patch behind her right shoulder blade at the edge of her blanket. After turning this one inside out in my mind, I came up with this explanation. This had to be the result of the white spotting gene expressing itself in a weird way. Instead of the typical white facial marking and white or paler extremities, it seemed as if the gene express itself throughout the body! If there is such a thing as a poorly expressed Classic Tuxedo grey, could there be such a thing as an overly expressed Classic Tuxedo grey? I couldn’t however explain how silver markings made their way onto this female without suspecting that maybe, just maybe, the dam Sati actually carried a recessive black. After producing 4 crias in the red realm, could she possibly have been hiding this from us?!
Cria #4 DSG (when bred to Male #2)
Bingo! A second grey out of this beige female but this time it’s a silver! This cria looks rose-grey on the outside (discolored tips) but is DSG inside! This confirmed my theory that this dam actually did carry a recessive black allele after all. This also explains how silver makings made their way onto cria #3 and possibly confirms the theory of it being an overly expressed Classic Tuxedo.
Cria #4 is probably one of the most satisfying scenario as this might in fact be her last cria as we had planned on retiring her from our breeding program. She has given us only female crias throughout her breeding career and most of them are now part of our reproductive crew. Needless to say that we are now rethinking our retirement plan for this dam!
conclusion of case studies
What you didn’t know is that Sati is in fact Sierra’s dam. We had concluded that Sierra had received the recessive black from her sire but we now know that it might have in fact been passed down from her dam Sati instead. Both females we thought were SSrr were in fact SSrb!
Calculating and recording results has allowed us to discover recessive alleles with these two females and adjusting our breeding strategies accordingly. We now know that we can produce silvers and blacks with both female within one generation instead of two.
Here are a few case studies at our farm. These are cases where this way of calculating color and pattern predictions and verifying the results against them has helped us figure out which recessive alleles were hiding behind our solid non-grey breeders.
Sometimes, if we are lucky, hidden recessive genes will show up quickly. In some other cases, it might take many offspring to fully understand the secrets behind them.
Female – Beige - 5 years old
Has produced 2 crias and expecting a 3rd one shortly. Expected this female to be a Solid Red with no recessive allele as her dam is beige and sire is also beige. We had chosen her sire based on the fact that he had produced progeny with amazing fleece traits and that he had thrown some darker colors, even some black when bred to black.
Presumed genetic combination for Sierra was SSrr
First breeding was to a MSG so as per calculations, we expected a solid red or a Classic Tuxedo rose-grey. The bonus with this breeding is that the possible solid colored red cria would now carry a recessive black allele passed on from its silver sire. We figured that within 2 generations, we could be producing black or silver with this line! Little did we know…
Results: A beautiful female which looked beige just like her dam…oh but wait is that a silver?!
Turns out Sierra was not an SSrr after all but an SSrb! She has received a recessive black probably from her sire and we now know that she has the capacity of throwing solid black or silver. We were very lucky to get this result on our first try! It could have taken many crias before discovering this.
Revised prediction chart for Sierra when bred to a silver-grey:
The results are now slightly more diluted with 4 x 25% BUT 75% of the possible results now fall within our desired color outcomes (black, rose or silver)!
I think we can all agree that greys are indeed fascinating! Hopefully this article has convinced you that breeding strategies must be put in place if you are going to be successful in breeding them. At the game of colors and patterns, sometimes you win, sometimes you lose but you always end up learning something from your individual breeders if you are paying close attention to the results.
A recent study by Dr Kylie Munyard B.Sc. (Hons PhD, School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Australia) has narrowed in on a way to genetically identify Classic grey alpacas by pinpointing a certain mutation in the KIT gene that seems to be responsible for the white spotting expression of Classic greys. This is obviously great news for any grey breeder and more in depth studies will certainly be conducted on the subject in years to come.
Decoding your alpaca’s genetic heritage can help you make better breeding decisions that are in line with your color program and keeping track of those results can only enhance your accuracy in producing certain colors or patterns with a certain level of predictability. This is a powerful tool that should not be underestimated in any color breeding program!
Hope you enjoyed the read. If you have any questions, want to discuss greys or maybe have your own theories or cases you would like to share, please feel free to contact me.
All the best in breeding amazing greys!
Alpagas Sutton Inc.
References & Suggested Reads
Inheritance of White Colour in Alpacas - Identifying the genes involved - by Kylie Munyard
July 2011 RIRDC Publication No. 11/074 RIRDC Project No. PRJ-000060
Alpaca Color Genetics: The Genetics of White Markings
By D. Andrew Merriwether, Ph.D. and Ann M. Merriwether, Ph.D.
The Alpaca Color Key
By Elizabeth Paul