Exam 3 Flashcards
Name a qualitative simply inherited trait.
Coat color
Name a qualitative polygenic trait.
Litter size
What special name is given to qualitative polygenic traits?
Threshold traits
Name a Quantitate polygenic trait
Ribeye Area
Rank the trait types in order of easiest to to most difficult to select for.
- Qualitative Simply Inherited
- Quantitative Polygenic
- Qualitative Polygenic
Which trait alleles (disease) are dominent for color?
Black
What are two ways you can manage or select against a genetic abnormality?
- Cross breeding
2. DNA test-cull carriers
Why is crossbreeding effective at eliminating the appearance of genetic abnormalities?
1) Recessive abnormalities-is not shown on carriers
2) Most only segregate in one breed
Why is selection for a simply inherited trait often easier than selection for a polygenic trait?
1) SI are only affected by a few genes
2) Polygenic are affected by environment factors such as diet
Which allele is dominant in Porcine Stress Syndrome?
Stress Resistent
Is the HYPP allele dominant?
Yes
Why are genetic abnormalities found more often in Angus cattle?
1) Largest registered breed in North America
2) Use of line breeding
T/F Genetic abnormalities are not segregating in some breeds.
False
How do genetic abnormalities commonly start appearing in the livestock industry?
Line breeding started many genetic abnormalities
The correlation coefficient measures two aspects of covariation. What are they?
Measures strength and direction between variables
The standard deviation of egg weight in chickens is 5 grams. What does this quantity mean?
The average deviation of the mean egg weight in this flock is 5 grams
Heritability is estimated by a ratio of what?
Variences
Genetic correlations are estimated by the calculation of what?
Correlation
Inbreeding coefficients are estimated by the calculation of what?
Correlation
Breeding values and progeny differences are estimated by what?
regression
Selection indicies are estimated by what?
Regression
Variance, standard deviation, correlation and regression all assume that the data follows what type of distribution?
Normal distribution
Explain why it is possible to completely eliminate a dominant allele from a population through selection but nearly impossible to remove a recessive allele, assuming DNA test does not exist.
1) You can differentiate carriers from a recessive carrier (phenotype)
2) When the frequency of the recessive gets really low in a herd most of those recessive alleles are found in heteros
T/F Inbreeding and crossbreeding will affect allele frequencies.
False
T/F Inbreeding and crossbreeding will affect genotype frequencies.
True
What does BV stand for?
Breeding Value
How is it possible for the true breeding value of an offspring to be greater than the average of the true breeding values of its parents?
Because of Mendallion Sampling
Why are additive gene effects transmitted to offspring yet gene combination values are not transmitted to offspring?
Because only one allele can be passed on. To pass on dominance both would have to be passed on
Seedstock producers are more interested in improving breeding values. Why?
They can be transmitted to the offspring and they want to sell genetics
Compare and Contrast Breeding Value with producing ability. Why are both of these used?
- Breeding Value-Genetic value as a parent, allows producers to make selection decisions
- Producing ability- Future performance predictor, allows for culling decisions to be made
- Both predict values of the animal
What is measured by the mean?
Average of the data sets
What is measured by the standard deviation?
The spread of the data but in units that are easier to interpret
What percent of a population would fall within one standard deviation from the mean
68%
What is measured by a regression coefficient?
Estimate the expected change in an observation per unit change in a second observation
Define Hardy Weinberg Equilibrium.
When no forces are acting to change allele frequencies. Alleles will not change
