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One theory of alpaca coat color inheritance stands apart from all the others.
Researchers William L. Wall and Ron G. Cole, of Australia, who both own
alpacas, propose that Mendel's rules of dominance and independent assortment do
not entirely explain the inheritance of coat color in alpacas.
Wall's area of interest is agricultural sciences, especially genetics; Cole
comes from a mathematics background. They propose a model of inheritance based
on gene linkage.
The Wall and Cole theory of inheritance grew from their statistical analysis of
matings that were registered by the Australian Alpaca Association's registry.
In all, they studied the color of more than 10,000 cria from registered parents
whose coat color was known. The results of these matings were compiled in two
sets of coat color tables (presented in their entirety in tables 1-12): Version
1, which compiled the coat colors of over 7000 cria, and Version 2 which
included the coat colors of an additional 3,000 cria.
Wall and Cole's theory of coat color inheritance in alpacas formed as result of
analyzing Version 1 of the tables. They then used their theory to predict the
color distribution among the additional cria. These are the figures charted in
Version 2. The accuracy of their predictions lends considerable credibility to
their ideas.
The goal of the Wall and Cole research
was to:
| 1. |
Determine the minimum number of genes necessary
to explain the range of colors found in alpacas; |
| 2. |
Map the genes on the chromosomes; |
| 3. |
Explain the action of modifier genes; |
| 4. |
Explain the action of the multi gene. |
In the process, they concluded that coat color inheritance was determined by the
process of gene linkage and not by dominance and simple assortment. They
further concluded that there were five genes total: three primary color genes -
black, red, and white - which are linked on the same chromosome; a modifier
gene which determines the amount of color; and a multi gene which determines
the distribution of color. Walland Cole hypothesize that the chromosomes
carrying the three linked color genes resemble the above diagram.
Once Wall and Cole settled on the gene linkage method of inheritance, and
determined from their coat color tables the relative distance apart of the
linked genes, they were ready to predict the outcome of the additional matings
that were included in Version 2 of the coat color tables. Their predictions
were more than 90 percent accurate.
Because the B, R, and W genes are linked, this allows for 64 possible genotypes
(4 alleles X 4 alleles X 4 alleles = 64) which are expressed as 27 phenotypes.
This conclusion is reached by taking the B (black) gene, the alleles of which
are B and b (where BB, Bb, bB, or bb represent four possibilities), and making
the same assumption for R and W, therefore 4 X 4 X 4 = 64. However, as Bb and
bB are indistinguishable, there are three phenotypes (BB, Bb, and bb). The same
is true for R and W. Therefore3 X 3 X 3 = 27 phenotypes.
In similar fashion, Wall and Cole theorized that the diluter gene has four
genotypes and three phenotypes: DD, Dd, dD, and dd. When you take the 27 color
phenotypes available and multiply them by the three diluter gene phenotypes,
the result is a potential for 81 different phenotypes. This range of possible
color shades explains every conceivable alpaca color. These colors would occur
on a continuous variation from light to dark, red to brown, fawn to white, etc.
The research derived from the color tables also led Wall and Cole to theorize
that there are three alleles of the multi gene: O, o, and ø with solid (O)
dominant. The multicolored coat in alpacas is expressed in many forms. These
forms include
| 1. |
A small white blaze on the face of an otherwise
totally black animal; |
| 2. |
Boots (i.e., feet and lower leg colors different
from the coat color expressed over the rest of the animal); |
| 3. |
White on white or black on black (i.e., white
spots on a white-coated animal or black patches on a black-coated animal which,
because of the base color of the animal's coat, are unseen as spots or
patches). |
All grays in this genetic context are considered multis, with the possible
exception of "true solid gray."
Calculating the various possible phenotypes that would occur from specific
matings under this theory establishes that a two-to-one ratio of solid to
multicolored animals would result from matings of multicolored parents. This
conclusion is also consistent with the data found in the tables. Finally, their
research confirmed that all grays were multis with the black, red, and white
genes operating.
Wall and Cole's research was verified independently by examining published data
presented by Rigoberto Calle Escobar who, in his book Animal Breeding and
Production of American Camelid, reported the following results of a color
mating study conducted at La Raya Ranch:
From observations made at La Raya Ranch, 1,000 white
females mated with white sires produced 50 to 60 percent white offspring; 19
percent were light fawn; 17 percent were patched. In decreasing order came
cinnamon, light coffee, dark coffee and black. It was also verified that from
every 300 offspring of the white with white cross, only one completely black
offspring was produced. Similarly from the crossing of white sires with other
colored females (with exception of light spotted fawn) a predominance of the
mothers' color was noted. In the case of females with light fawn and spotted,
40 percent of the offspring were white. These results of color crosses which
have been verified, reinforce the thesis that color inheritance is complex and
is based on many pairs of genes which, because of a not very intense selection
in the herds, are maintained in a pool of genes of the population, conserving
color variability.
It is interesting to note how Wall and Cole's study's predictive value holds up
in explaining the results of the La Raya color mating study. Escobar's La Raya
observations and Wall and Cole's calculations from the Australian herd when
white was mated to white follows in Figure 12.
Breeding for Color in
Practice
What happens as a practical matter when you breed white to white, black to
black, one color to a different color or solid color to multicolor? Alpaca
breeders are fortunate to have Wall and Cole's exhaustive study of coat color
inheritance which is intended to be an easy reference for breeders (see Tables
1-12). The study is based on the phenotypic color of the parents and their
progeny; it is not intended to suggest the alpaca's genotype.
The base data for the Wall and Cole work was derived from the Australian Alpaca
Association registration database which records alpaca registrations with
designated colors. The tables were created from registrations as of March 1996
and included 10,849 alpacas.
There are two types of tables:
| 1. |
The solid color cross table, which presents the
progeny from crosses of sires and dams of the same color. Numbers of crosses
and sex of progeny are listed, together with numbers of cria for each solid and
each multiple color registered (Tables 1-8). |
| 2. |
The multi or grey color cross tables which list
number of matings and sex of progeny, together with results of analysis of each
color of male crossed with each color of female and vice versa for each of the
colors. There are four of these tables (Tables 9-12). |
It should be understood that the color tables can not be used to predict the
outcome of a specific cross between two animals. The data presented is an
analysis of the combination of all available data. It is meant to present the
results of past experience. An alpaca breeder might choose to study the various
tables to determine what has transpired in the Australian National Herd as a
guide to the likelihood of various possible color outcomes from specific
breedings. Wall and Cole suggest that readers of their coat color tables pay
attention to the "white space" in the tables. They point out that the absence
of offspring of particular colors, as evidenced by "white space," is as
informative as the offspring recorded in the tables.
Observations On Color
Matings
In the Australian color mating tables (Tables 1-12), the color of the alpacas
were grouped as follows:
| 1. |
Fawn and roan alpacas were assigned to red; |
| 2. |
Silver grays and blacks were assigned to black; |
| 3. |
Browns were assigned to brown; |
| 4. |
Whites were assigned to white; |
| 5. |
Multicoloreds were assigned according to the mix
of colors listed, for example, a dark fawn/light fawn/white alpaca was assigned
to red; a dark fawn/medium gray alpaca (roan) was assigned to brown. |
Understanding this, you can use the charts to make the following observations:
| 1. |
When breeding white to white, the progeny were 60
percent white; 18 percent red; 17 percent brown; and five percent black. |
| 2. |
When breeding white to brown, the progeny were 43
percent brown; 10 percent black; 27 percent red; and 20 percent white. |
| 3. |
When breeding black to black, the progeny were 85
percent black; 11 percent brown; one percent red; and three percent white. |
| 4. |
When breeding white to black the progeny were 24
percent white; 14 percent red; 30 percent black; and 32 percent brown. |
| 5. |
When breeding brown to black the progeny were 52
percent brown; 40 percent black; three percent red; and five percent white. |
The Bottom Line
The color of the progeny can often be predicted with accuracy if the breeder is
familiar with the stud being used, particularly if he has sired a large number
of offspring. A famous alpaca stud, Hemingway, is a good example. He has been
bred to more than 30 black females. All the offspring, 100 percent, have been
fawn, mostly dark fawn. When Hemingway is bred to solid-colored females, such
as brown or fawn, he almost always produces a lighter colored cria in the same
basic color of the mother; when bred to white females, he produces white cria.
Accoyo's El Moustachio (white) and Accoyo's Victor (fawn) often produce a cria
the color of the mother, especially Victor, who has thrown a lot of black cria
when mated to black females.
The highest likelihood for creating a certain color occurs when mating two
alpacas of the same color. Alpacas seem to carry a variety of color genes,
especially white alpacas. If Cole and Wall are correct, every alpaca carries
every color. When crossing a white alpaca with a colored alpaca, the progeny
are more likely to be colored than white by a considerable margin. Two colored
alpacas almost always result in colored progeny. Pintos can pop up almost
anywhere or, as Barreda says, "pintos are hard to get rid of."
Alpaca breeders need to form their own goals as to colors. If they want to
produce unique colors for the pet market, they can mix up solids with
multicolors, black with white, and so on. If their goals involve eventually
producing commercially valuable fiber, they can breed solid to solid,
preferably white.
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