Monday, May 10, 2010

Sancha

Our only resident pool user:



Our first due female, this season, is Sancha. Sancha is twelve years old. She is white, with a good size fawn spot on one side. We've heard different meanings to that spot. Some believe it means her secondary color is fawn (every alpaca has 2 color genes, one they display, the other is their secondary color that they do not show, but could pass onto an offspring). Others believe the spot is not at all related to the secondary color but instead is a dark spot gene. There is another theory that she could be a fawn animal with a big white spot. I have also heard that dams with these fawn spots are more likely to have grey offspring. While those studying alpaca color genetics know quite a bit, there is still some things they don't know for sure. We tend to believe the dark spot gene theory, but we think in Sancha's case, it just so happens that her secondary color likely is fawn (which wouldn't be the case for every alpaca, just so happens to be for her). If this is a dark spot gene, then 50% of the time Sancha should pass on this dark spot. We have first hand experience with 3 of Sancha's offspring. Sommerfield did not have a fawn spot, Lightning did, Lily did not. (Lightning's fawn spot is on his chest, so it seems it can show up anywhere on the alpaca). That seems to fit that she would pass it on some of the time.



Each alpaca has 2 color genes, one they get from their dam (mother) and one they get from their sire (father). Of these 2 colors, only one shows on the outside of the alpaca (dominant color, or primary color). The lighter color is primary, so their secondary color is always a darker color. When they become a parent, they pass one of these genes onto their cria (children). Each time they have a cria, they have a 50% chance of passing on their primary color, and a 50% chance of passing on their secondary color. For most of our alpacas, we know what their secondary color has to be. If you look at their parents and their offspring (if there are any) you can often easily figure out what it has to be. For example, if they have a black parent, they have to get a black gene from that parent, because black is only created by 2 black genes (otherwise the lighter color would be displayed). Even if their parents are two whites, you can figure out what the secondary colors are, if you have enough information on their parents and enough offspring.

With Sancha we aren't completely sure what her secondary color is. Sancha's parents are white and fawn. She is white, so she had to have gotten a white gene from her father. From her mother she either got fawn, or whatever her mother's secondary color is. While writing this post, I decided to try and figure it out. Sancha's mother is an import, which makes it hard to research her to find out what her secondary color is. We don't know her parents. I pulled up a list of her offspring off of ARI (very handy to be able to access that). I discovered that Sancha's mom has had 7 registered offspring. 6 are white (she was bred to white most of the time). One of her offspring is a true black (she was bred to a true black). This means Sancha's mother's secondary color is black. The only way to get black is to have 2 black genes, so she had to pass on a black gene to that offspring. So Sancha either received a fawn gene from her mother, or a black.

Sancha has had 7 cria, 6 of which are white. The other is a Dark Rose Grey. Now, having never seen this dark rose grey, I can't say with 100% certainty if this rose grey is a brown or a fawn base (animals are not always registered exactly right, a dark rose grey should be brown base, but it's hard to know how accurate all this is). That is actually critical in figuring out Sancha's secondary color. If this rose grey is a fawn base, then Sancha's secondary color is fawn. If it is a brown base, then Sancha's secondary color is black (the brown from the dark rose grey would be from the sire who was a dark rose grey himself, then black would be this cria's secondary color). We believe Sancha's secondary color to be fawn, but can't be 100% sure. We won't know unless she has a black cria, proving her secondary color to be black. Or, if she has a fawn when the male is darker, it would prove her secondary color is fawn.

Statistically each time Sancha is bred, she has a 50% chance of passing on a white gene (which would be dominate and would be the cria's color), and her secondary color 50% of the time. With her having had so many white cria, we can't pull out for sure what her secondary color is.

Sancha is currently bred to Apollo. He is light brown (note, the light/medium/dark of the color shade doesn't factor into the 2 color gene issue, it could be any shade of that color, if you have a brown gene, it could display as light/medium/dark differently in each animal in the family tree, all that matters is the fact it's brown). Apollo's mother is white, but has a brown as her secondary color. Apollo's primary color, brown, he got from his mother. Apollo's father is black, so he had to have passed on a black gene to Apollo. This means Apollo's secondary color is black. Apollo could pass on a brown (B) or black (b) gene. Both of which should be darker than Sancha's white and fawn (likely secondary color).

So we have bred (I'll use a lower case b=black because it's not dominate, and to differentiate it from (B)rown. W=white, F=fawn):

Using basic algebra (or you could do those squares they teach in high school genetics)
Apollo (Brown and black) x Sancha (White and Fawn) =
Bb x WF = BW, BF, bW, or bF

Remember the lighter color trumps the darker color so:
BW = white (Brown gene and White gene means the White primary)
BF = fawn
bW = white
bF = fawn

This means we have a 50% chance of a white cria, and a 50% chance of a fawn cria.

Now if we are wrong on Sancha's secondary color, and it is actually black (which it could be, right now we have no proof either way), the colors change for this expected cria. Instead it would be:

Apollo (Brown and black) x Sancha (White and black) =
Bb x Wb = BW, Bb, bW, or bb
BW = white
Bb = brown
bW = white
bb = black

So, if we get a white cria this year, we will know nothing more about Sancha's secondary color. But if we get a fawn, we know, for sure, her secondary color is fawn. If we have a brown or black cria, we will know that Sancha's secondary color is black. I can't wait to see!

Sancha is due the end of May. We set her due date at day 350 because we've found she usually delivers a few days after that (day 356 or so). She has now had 2 cria born at our farm, both were born just after day 350, and both were over 20 pounds. We expect the same from her this year.

With each of our breeding girls, we pick a theme to name all of their cria. Sancha's theme is: nature. So far we have named: Sancha's White Lightning, and Snow Lily by Lord Stanley. After Lighting and Lily, I almost think we have an L theme going too!

2 comments:

Debbie, Barnacre Alpacas said...

We have an identical spot on one of our girls Duchess. She only threw the spot once on Hughie (who was castrated yesterday), all her other cria were solid colours no matter if we put her to white or brown.

cara said...

That is interesting. I always wonder how theory on the genes plays out in the real world. I do know that it is a 50% chance each time, which isn't exactly the same as saying 50% of their offspring should have it. It's like having a male vs a female, there is a 50% chance each time of one or the other, but we've all seen times there are either more males or more females.

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