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Alpaca Genetics
Glossary of Alpaca Terms
RANDOM MATING:
The joining of animals on an entirely random basis without regard to pedigree
or phenotype.
RECESSIVENESS:
See DOMINANCE.
RECOMBINATION:
The formation of a new combination of genes on a chromosome as a result of
crossing over.
REFERENCE SIRE:
These sires leave offspring in several, possibly all, of the cooperating
flocks. The offspring of the reference sires can then be compared with the
offspring of any other sires used in the same flock. Thus, the best males in
the whole of the group breeding scheme: 1) can be identified, with the help of
appropriate statistical programs; 2) can become available to the scheme as a
whole; and 3) can be used to breed the next generation of males.
REPEATABILITY:
(1) A measure of the strength of the relationship between repeated records
(repeated phenotypic values) for a trait in a population. (2) A measure of the
strength of the relationship between single performance records (phenotypic
values) and producing abilities for a trait in a population. (3) In dairy
publications, accuracy of prediction.
REPEATED BACKCROSSING:
A mating system used to incorporate an allele or alleles existing in one
population into another population. An initial cross is followed by successive
generations of backcrossing combined with selection for the desired allele(s).
REPEATED TRAIT:
A trait for which individuals commonly have more than one performance record.
REPLACEMENT RATE:
The rate at which newly selected individuals replace existing parents in a
population.
REPLACEMENT SELECTION:
The process that determines which individuals will become parents for the first
time.
ROAN:
Animal coat color determined by a fairly uniform mix of colored fibers. For
example, the coat of a silver alpaca is actually made up of intermittent black
and white fibers.
ROUND LOT:
Standard, historical sale unit of raw alpaca fiber which was made up of several
colors in agreed-upon percentages. The term is no longer used.
SEEDSTOCK:
Breeding stock; animals whose role is to be a parent or, in other words, to
contribute genes to the next generation.
SEGREGATION:
The separation of paired genes during germ cell formation.
SELECTION:
The process that determines which individuals become parents, how many
offspring they may produce, and how long they remain in the breeding
population.
SELECTION ACCURACY:
Also accuracy of breeding value prediction. The measure of the strength of the
relationship between true breeding values and their predictions for a trait
under selection.
SELECTION CRITERIA:
Phenotypic values or other pieces of information that form the basis for
selection decisions.
SELECTION DIFFERENTIAL:
The difference between the mean selection criterion of those individuals
selected to be parents and the average selection criterion of all potential
parents, expressed in units of the selection criterion.
SELECTION INDEX:
A linear combination of phenotypic information and weighting factors used for
genetic prediction when performance data comes from generally similar
contemporary groups. See also economic selection index.
SELECTION INTENSITY:
(1) A measure of how particular breeders are in deciding which individuals are
selected. (2) The difference between the mean selection criterion of those
individuals selected to be parents and the average selection criterion of all
potential parents, expressed in standard deviation units.
SELECTION RISK:
The risk that the true breeding values of replacements will be significantly
poorer than expected.
SELECTION SYSTEM:
The method a breeder chooses to select breeding stock.
SELECTION TARGET:
A level of breeding value considered optimal in an absolute or practical sense.
SIMPLY INHERITED TRAIT:
A trait affected by only a few genes.
SINGLE-TRAIT SELECTION:
Selection for one trait.
SIRE:
A male parent.
SIRE SUMMARY:
A list of genetic predictions, accuracy values, and other useful information
about the sires in a breed.
SKEWBALD:
Pinto; in the New Zealand color study, an alpaca with white and brown patches.
SLIVERS:
A continuous, untwisted strand or rope of parallel alpaca fibers approximately
uniform in cross-section, produced by the carding and drawing process. Carded
slivers are blended prior to combing in the manufacture of worsted yarn.
SOLES:
Peruvian currency.
SPERM CELL:
Gamete.
SPOTTING GENES:
A gene which may control spots or color pattern on an alpaca. The existence of
a spotting gene has not been scientifically verified.
STANDARD DEVIATION:
A mathematical measure of variation that can be thought of as an average
deviation from the mean. The square root of the variance.
STAPLE LENGTH:
The length of a lock or length of shorn alpaca fleece.
STAPLE:
An organized independent group or cluster of individual fibers. A large number
of staples constitute a fleece.
SURI:
A breed of alpaca characterized by lustrous locks of fleece that lay close to
the body, twisting vertically toward the ground.
SYNDACTYLISM:
Having two or more toes fused together.
TEMPORARY ENVIRONMENTAL EFFECT:
An environmental effect that influences a single performance record of an
individual but does not permanently affect the individual's performance
potential for a repeated trait.
TERMINAL SIRE:
A paternal-breed sire used in a terminal sire crossbreeding system.
TEST CROSS:
Also test mating. A mating designed to reveal the genotype of an individual for
a small number of loci.
TOPCROSSING:
Grading up.
TOPS:
A continuous, untwisted strand of combed alpaca fibers from which the shorter
fibers have been removed by combing.
TRAIT:
Any observable or measurable characteristic of an individual.
TRAIT OF THE DAM:
A trait in which each progeny record is attributed to the dam, not the
offspring.
TRAIT OF THE OFFSPRING:
A trait in which each record is attributed to an offspring, not to its dam.
TUI:
An eighteen-month-old alpaca.
VALUE:
Any measure applied to an individual as opposed to a population. Examples are
phenotypic value, genotypic value, breeding value, and environmental effect.
VARIABILITY:
The differences between animals within a given population.
VARIATION:
In most animal breeding applications, the differences among individuals within
a population.
VICUNA:
Native South American camelid, thought to be the ancestor of the domesticated
alpaca. Vicunas, which exhibit the finest natural fiber in the world, can
cross-breed with alpacas.
YARA:
Quechua word for the color black.
WOOLEN:
Yarn made from fibers that are one to three inches in length and that have been
carded only. Fabrics of woolen yarn are characterized as being fuzzy, thick,
and bulky.
WORSTED:
Yam spun from fibers three inches in length or longer that have been carded,
combed, and drawn. Combing machines straighten alpaca slivers, making the
individual fibers lie parallel.
YURAQ:
Quechua word for the color white.
ZYGOTE:
A cell formed from the union of male and female gametes. A zygote has a full
complement of genes - half from the sperm and half from the egg.