Alpaca Heritage Sale - Alpaca Genetics

Educational Articles

You vaguely remember the lesson. While the biology teacher droned on about Mendelian Gene Action, you allowed your mind to drift. What was so important about Gregor Mendel's discovery anyway? You didn't intend to grow peas, no animals were being bred at your house, and you certainly did not intend to pick your future spouse based on Mendelian or any other genetic principles.

But here you are... many years later... and you sure would like to understand why your black alpaca female bred to a black stud produced a chocolate brown cria. Also, where did that stubborn streak in your kid come from when you and your spouse are such easy-going people?

Are genetics, especially color genetics, complicated? You bet! However, even a lay person can and should understand the basic laws guiding genetic principles. Years ago, my small-statured sister bemoaned the fact that the heights of her two tiny daughters fell off the growth charts at their pediatrician's office. My father looked first at her rather short husband and then back at my sister. "What did you expect?" he asked. "Mice make mice!"

Well, that's quite true, but it's not the whole genetic story. Humans as well as alpacas display certain measurable and observable traits such as size, color, and other conformational characteristics. We call that phenotype. As a breeder, you should understand though that genetic make-up is more than just phenotype. What you see is not all you get (it's sort of like getting married). Hidden away from sight, your alpacas also carry certain traits that may or may not stay "buried" for one or more generations. We call the entire genetic package an animal's genotype.

To quote my friend, well-known Borzoi breeder and American Kennel Club judge Barbara Ewing, that's why breeding will always be " a humbling experience."

We can all stand to be humbled once in a while, but breeders should also enjoy success based on research and knowledge, not just plain luck. A sound knowledge of genetics will server as the foundation of your breeding program. To achieve your goals, you also must study pedigrees and know as much as possible about the animals you are breeding, though I must admit that this is still often difficult with alpacas at the present time.

Let's get back to our original question of two black alpacas producing a chocolate brown cria. How can this happen?

Genes come in allelic pairs, just like shoes, mittens, and socks. You place such clothing on "assigned" matching locations of your body (two hands, two feet). Likewise, each pair of alleles resides at a specific address (locus) on matching (homologous) chromosomes inside the cell's nucleus.

Let's say a man owns two green mittens and two black socks. We call such identical pairs homozygous (homo=the same). His shoes, however consist of one black and one brown one. They are heterozygous (hetero=different). This man meets a woman who sports two red mittens, two black socks and the identical combination of shoes. Our fashionable couple produces a child. When it is time to clothe their offspring, each parent donated one mitten, one sock and one shoe (one allele for each trait) to their infant. Which possible combinations can this baby wear? His mittens would most certainly be green-red (heterozygous). In the sock department we know for sure he'll be wearing black-black (homozygous). The shoes... well, the shoes can surprise us. There are several possibilities. To work out the mathematical probabilities, we use a Punnett Square. In the figure below, "B" represents the black shoe, and "b" represents the brown shoe.

As you can see, Baby could be wearing two black (BB) shoes, or a black/brown (Bb) combination, or two brown (bb) shoes. Believe me, these parents don't care. They'll throw any shoe into the pile (gene pool). Which color mitten, sock, and shoe (allele) each parent passes on is entirely random.

Assuming that alpaca colors follow the inheritance patterns of other mammals, we will find that, at the Brown locus, B is the dominant and b the recessive allele. Dominant B masks the presence of the recessive b. Your cria will only be the rich, dark chocolate color if it is bb. We therefore have three possible genotypes (BB, Bb, and bb) but only two phenotypes- black and brown - with BB and Bb both showing as black.

"OK, this is easy," you say. "I substitute alpaca fleece color alleles for shoes. Now I know why my two black alpacas produced a chocolate brown cria. You're telling me that black is dominant over brown in alpacas. Simple! Forget all this sock and shoe stuff."

Not so fast! While black is probably under recessive genetic control at the Agouti Locus, the B locus determines its expression as either black or brown.

D. Phillip Sponenberg, DVM, PhD tells us that "the Brown locus can modify the Extension-Agouti colors to make all the black areas chocolate brown. This is the brown of retrievers, and lacks redness to its shade."

Hold on, don't run off screaming into the night. You'll understand this in a minute. I won't use my nieces (the mice) to clarify this concept, but will instead tell you of my poor brother's role as a reluctant fashion plate. Being married to a woman who firmly believes in wearing the proper outfit for every occasion, my hapless brother has to pass inspection every morning. Watch out if the color of his underwear doesn't coordinate with the rest of his outfit! Special attention is paid to the color of his socks matching the color of his shoes. The fashion police dictate that he may only wear black or dark brown shoes if his socks are also black. Since he puts his socks on before his shoes, they determine the shoe color (Isn't it convenient to have one's family live on another continent? I hope they'll never meet a German alpaca breeder who reads Alpacas Magazine!)

Let's translate this into alpaca language. The socks represent the Agouti Locus. the shoes the B locus. The choice at the Agouti Locus is black (a) versus red with black trim (A) . The choice at the B locus is black. (B) versus brown (b). Only if the allele at the Agouti Locus code for black do the B alleles have a chance to "show off their stuff" over the entire body. The B locus probably does not exist in horses. The various browns of the latter are under different genetic control, as are all the red-based browns of alpacas, llamas, and other mammals.

In contrast to the well-established color inheritance patterns of other species, specific details of alpaca color genes remain under much speculation. Nevertheless, there is plenty of evidence to suggest that black is a recessively-inherited trait in alpacas. The B locus alleles merely act as a switch to allow expression of either black or brown. An AA BB or Aa Bb alpaca, for example, would not be black, but red with black trim. The chocolate brown baby is, in essence, a modified black.

If, at the Agouti Locus, A represents dominant red and a recessive black, your black alpaca's genotype can be described as aa BB or possibly aa Bb. Your dark, chocolate brown cria would be aa bb. Referring back to the Punnett Square, you can easily see that in order for two black alpacas to produce a chocolate baby, the genotype of both parents must be aa Bb. It follows that two chocolates can only produce chocolate.

Color inheritance is very complicated, and this short article only touches on its complexity. Please remember that genes which extend and dilute the basic colors further complicate this issue. The incredible diversity of fleece color adds to my personal fascination with breeding alpacas. From Aa to Bb to Pp (we'll talk about the P locus another time)... study and enjoy them all!

Should you ever travel to Germany and meet a man whose underwear color matches the rest of his outfit - please say "Guten Tag." Tell my brother that if he visits Stormwind Farm, he may wear whatever pleases him. The alpacas won't care. As a matter of fact, they enjoy unusual color combinations. Bring out the bay black underwear and medium silver gray socks!