Exam 2 Flashcards
Selection Index
A linear combination of phenotypic info and weighing factors that is used for genetic prediction when performance data comes from genetically similar contemporary groups
Fitness
The ability of an individual and its corresponding phenotype and genotype to contribute offspring to the next generation
Nucleus Breeding Scheme
A cooperative breeding program in which elite animals are concentrated in a nucleus herd or flock and superior germ plasm is then distributed among cooperating herds or flocks
Quantitative Genetics
The branch of genetics concerned w/influences on measurement of, relationships among, genetic prediction for, and rate of change in traits that are or can be treated as quantitative
Progeny Difference
The expected difference between the mean performance of the individual’s progeny and the mean performance of all progeny
Gene Combination Value
The part of an individual’s genotypic value that is due to the effects of gene combinations (dominance and epistasis) and cannot, therefore be transmitted from parent to offspring
Phenotypic Correlation
Measure of the strength of the relationship between performance in one trait and performance in another
Genetic Correlation
Measure of the strength of the relationship between breeding value of one trait and breeding values of another
Contemporaries
A group of animals that have experienced a similar environment w/respect to the expression of the trait
Genetic Trend
Change in the mean breeding value of a population over time
Heritability
Measure of the strength of the relationship between performance (phenotypic value) and the breeding values for a trait in a population
Repeatability
A measure of the strength of the relationship between single performance records and producing abilities for a trait in a population
Accuracy
A measure of the strength of the relationship between true breeding values and their predictions for a trait under selection
Selection Target
A level of breeding value considered optimal in an absolute or practical sense
Producing ability
The performance potential of an individual for a repeated trait
What are the three methods of multiple-trait selection
Tandem Selection
Independent Culling Levels
Economic Selection Index
Two types of Genetic Prediction discussed in class:
Selection index and BLUP
T/F: Genetic correlations reduce bias caused by culling for poor performance and improve accuracy of prediction
True
T/F: If unaware or ignore unfavorable correlations, selection for one trait can lead to undesirable response in other
True
T/F: Tandem Selection works well when traits are unfavorably correlated
False
Used to compare animals using data from genetically diverse groups
BLUP
T/F: Large scale genetic evaluation improves both intensity and accuracy of selection
True
T/F: Zero in a genetic evaluation is always the population mean
false
T/F: GxE interactions can cause re-ranking of individuals (sires) in different geographical areas or management systems
True
T/F: Threshold traits are polygenic
True
Which traits have low heritabilities (
fertility
As related to fitness, less desirable genes reach an intermediate frequency that cannot be further diluted
overdominant
T/F: Hybrid vigor is a positive effect of Gene Combination Value
True
Heritabilities of carcass traits in livestock
high
T/F: All traits are heritable
false
T/F: Pedigree estimates are used in parent EPDs for non-sire genetic evaluations
false
T/F: accuracy of selection is highly dependent on heritability
True
T/F: if sires are genetically superior to dams, save many female replacements
true
T/F: Multi-trait selection increases genetic change by reducing selection intensity
false
MOET?
Multiple Ovulation, Embryo Transfer
A trait that may or may not be important in itself, but is selected for as a way of improving some genetically correlated trait is:
Indicator trait
Genotype (G) = Breeding value +
Gene Combination Value
Producing ability is the performance potential of an individual for what kind of trait?
Repeated
Name two ways to improve Heritability and Repeatability
Environmental Uniformity and accuracy of Data
What are the three directly proportional factors that effect Genetic Change
Accuracy of Selection, Selection intensity, and Genetic Variation
What factor has an inversely proportional effect on Genetic Change
Generation Interval
The risk that the true breeding values of replacements wil be significantly poorer than expected is:
Selection risk
What are two common environmental adjustments for heritability and repeatability
age and sex
The formula used to account for contemporary group effects is called a
trait ratio
For the Quantatative Model
P= (MU) + G + E
In threshold traits, “Threshold” is the point where what changes
phenotype
A weighted combination of traits defining aggregate breeding value for use in an economic selection index
Breeding objective
BLUP stands for
Best Linear Unbiased Predictions
What is a Central Test Station
A place where animals (usually males) are asked to perform under same environment
What are three types of info found in Sire Summaries?
Animal ID, Misc. info, and Prediction of accuracy info
What are three factors affecting Accuracy of Prediction related to Selection index
Heritability, pedigree relationship, # of records, progeny records
What are two ways in which accuracy is conveyed in Sire Summaries
Correlation (repeatability), Confidence ranges, probable change (standard error)
What is one reason that indirect Selection is performed on correlated traits?
Direct Selection is too expensive to measure; Better accuracy w/indirect; and direct trait is a threshold trait
One standard deviation of the mean is a what % probability of occurrence
68%
