AS 332 Exam 3

What is an example of a qualitiative simply-inherited trait

Coat color, polled/horns, genetic abnormalities

what is an example of a qualitative polygenic trait

litter size,f ertility, temperament, disease resistance

what is an example of quantitative polygenic trait

weight, yield (milk production)

what causes genetic abnormalities to appear in animals

inbreeding

Overo Lethal White Syndrome

Horses, recessive, linked (but not completely) to overo coat color, foal cannot pass feces and is born completely white and dies, not all overo horses have OLWS

in cattle, the traits of conception rate (conceived, not conceived) and coat color (black, red) are qualitative traits. Only one is polygenic. the other trait is simply-inherited. White trait is polygenic? What is the special name given to polygenic traits that are qualitative?

conception rate. Threshold trait

rank qualitative simply-inherited, qualitative polygenic, and quanitative polygenic traits by easiest to most diffult to improve

qualitative simply-inherited > quantiative polygenic, qualitative polygenic

what is the recessive allele in scrapie: resistant or susceptible

susceptible

what is the recessive allele in spider lamb syndrome - healthy or diseased

diseased

what is the recessive allele in double muscling - normal or double-muscled

double muscled

what is the recessive allele in developmental duplication - healthy or diseased

diseased

at is the recessive allele in bovine brachyspina syndrome - Healthy or diseased

diseased

what is the recessive allele in coat color in cattle - black or red

red

what is the recessive allele in arthrogryposis multiplex - healthy or diseased

diseased

what is the recessive allele in tibial hemimelia - healthy or diseased

diseased

what is the recessive allele in horns in cattle - horned or polled

hornedw

hat is the recessive allele in porcine stress syndrome - stress susceptible or stress resistant

stress susceptible

what is the recessive allele in rendement napole - normal or acid meat

normal

What is the recessive allele in hyperkalemic periodic paralysis (HYPP) - healthy or diseased

healthy

what is the recessive allele in overo lethal white syndrome (OLWS) - healhty or diseased

diseased

what are the four ways you can manage for or select against a genetic abnormality

DNA test and cull carriers. DNA test sires and use only non-carriers. Crossbreeding. DNA testing and mate carriers to non-carriers

why is crossbreeding effective at eliminating the appearance of genetic abnormalites

most genetic abnormalities are recessive. Most genetic abnormalities are present in only one breed

why is selection for a simply-inherited trait often easier than selection for a polygenic trait

only one loci or a few affect the trait. the environment has minimal effect on the trait

true/false - genetic abnormalities are segregating in only some breeds

false - if it said all breeds, it would be true

what is a mean

average

what is measured by a standard deviation

about the average deviation of an observation from the mean. 68% of your observations fall within one standard deviation of the mean

what is measured by a regression coefficieny

average change in Y variable given a 1 unit change in your X variable

_____ of your observations fall within one standard deviation of the mean

68%

what two aspects are measured by a correlation coefficient

direction. strength

the standard deviation of egg weight in chickens is 5 grams. What does this quantity mean

about the average deviation of an eggs weight from the mean is 5 grams. 68% of the egg weight will fall within 5 grams of the mean

breeding values and progeny differences are estimated by ___ (variance, correlation, regression)

regression

heritability is a ratio of ___ (variance, correlation, regression)

variance

selection indices are estimated by ___ (variance, correlation, regression)

regression

inbreeding coefficients are estimated by the calculation of a ___ (variance, correlation, regression)

correlation

genetic correlations are estimated by the calculation of a ___ (variance, correlation, regression)

correlation

all of these statistics assume the data follow a ___

normal distribution

Hardy-Weinburg Equilibrium

when no forces are acting, allele and genotype frequencies remain constant across generations. Genotype frequencies go to Hardy-Weinburg proportions

Allele frequencies can change in only four different ways. list the one force that cannot change allele frequencies

non-random mating

genotype frequencies can change in five different ways. list the forces that can change genotype frequencies

random drift. migration. selection. non-random mating. mutations

four forces can change allele frequencies in a population. give one force that is at work in each scenario: 1. a polled calf is born in a herd where all bulls and cows are horned. 2. I purchase cows from a local sale. 3. I do not retain animals with horns each breeding season. 4. in a closed herd, animals that are polled and have horns are present in each calving season. the herd manager retains calves irrespective of wehther horns are present

1. mutation. 2. migration. 3. selection. 4. random drift

what are the two reasons why it is difficult to eliminate a recessive allel from a population, assuming a DNA test for this recessive allele does not exist?

1. heterozygotes (carriers) look identical to homozygous dominant animals

2. As the frequency of the recessive allele decreases, most of these alleles are found in heterozygotes

True/False: inbreeding and crossbreeding by itself will change genotype frequencies

true

breeding value

genetic value of the animal as a parent

gene combination value

sum of dominance and epistatic effects at all loci affecting a phenotype

what is the mathematical relationship between an animals breeding value and its progeny difference (transmitting ability)

TA (PD) = ½(BV)

animal breeders are more interested in improving breeding values and progeny differences than gene combination values. Why?

only additive genetic effects (through alleles) are transmitted to offspring

why are breeding values and not gene combination values, transmitted to offspring

additive genetic effects are properties of alleles, not genotypes and only alleles are transmitted from parent to offspring

the true breeding value may be very different from the average of its parents breeding values. how is this possible?

mendelian sampling

repeated trait

a trait that can be measured multiple times in the same animalw

what are some examples of a repeated trait

milk yield, calving ease, litter size, racing speed

permanent environmental effect

environmental effects that permanently affect performance

temporary environmental effect

environmental effects that temporarily affect performance

compare and contrast breeding value and producing ability

same - both can be predicted

BV - used to make selection decisions

PA - used to make culling decisions

which terms (P = BV + GCV + Ep + Et) are the cause of 1. correlation between phenotypes of parents and their progeny. 2. The correlation between two repeated records of the same individual. 3. correlation between phenotypes of clones derived from the same animal. 4. prediction errors when phenotype is used to predict producing ability. 5. prediction errors when phenotype is used to predict breeding values

1. BV

2. Ep, BV

3. BV, GCV

4. Et

5. GCV, Ep, Et

In P = BV + GCV + Ep + Et, we often assume the terms on the right side of the equation are independent of each other. Why may this assumption not be true?

1. animals with superior genetics are often placed in better enviornments

2. animals BVs are reranked depending on the environment

True/False - genetic abnormalities are segregating in only some breeds

false