Exam 2

Question 1

Selection Index

Answer 1

A linear combination of phenotypic info and weighing factors that is used for genetic prediction when performance data comes from genetically similar contemporary groups

Question 2

Fitness

Answer 2

The ability of an individual and its corresponding phenotype and genotype to contribute offspring to the next generation

Question 3

Nucleus Breeding Scheme

Answer 3

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

Question 4

Quantitative Genetics

Answer 4

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

Question 5

Progeny Difference

Answer 5

The expected difference between the mean performance of the individual’s progeny and the mean performance of all progeny

Question 6

Gene Combination Value

Answer 6

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

Question 7

Phenotypic Correlation

Answer 7

Measure of the strength of the relationship between performance in one trait and performance in another

Question 8

Genetic Correlation

Answer 8

Measure of the strength of the relationship between breeding value of one trait and breeding values of another

Question 9

Contemporaries

Answer 9

A group of animals that have experienced a similar environment w/respect to the expression of the trait

Question 10

Genetic Trend

Answer 10

Change in the mean breeding value of a population over time

Question 11

Heritability

Answer 11

Measure of the strength of the relationship between performance (phenotypic value) and the breeding values for a trait in a population

Question 12

Repeatability

Answer 12

A measure of the strength of the relationship between single performance records and producing abilities for a trait in a population

Question 13

Accuracy

Answer 13

A measure of the strength of the relationship between true breeding values and their predictions for a trait under selection

Question 14

Selection Target

Answer 14

A level of breeding value considered optimal in an absolute or practical sense

Question 15

Producing ability

Answer 15

The performance potential of an individual for a repeated trait

Question 16

What are the three methods of multiple-trait selection

Answer 16

Tandem Selection
Independent Culling Levels
Economic Selection Index

Question 17

Two types of Genetic Prediction discussed in class:

Answer 17

Selection index and BLUP

Question 18

T/F: Genetic correlations reduce bias caused by culling for poor performance and improve accuracy of prediction

Answer 18

True

Question 19

T/F: If unaware or ignore unfavorable correlations, selection for one trait can lead to undesirable response in other

Answer 19

True

Question 20

T/F: Tandem Selection works well when traits are unfavorably correlated

Answer 20

False

Question 21

Used to compare animals using data from genetically diverse groups

Answer 21

BLUP

Question 22

T/F: Large scale genetic evaluation improves both intensity and accuracy of selection

Answer 22

True

Question 23

T/F: Zero in a genetic evaluation is always the population mean

Answer 23

false

Question 24

T/F: GxE interactions can cause re-ranking of individuals (sires) in different geographical areas or management systems

Answer 24

True

Question 25

T/F: Threshold traits are polygenic

Answer 25

True

Question 26

Which traits have low heritabilities (

Answer 26

fertility

Question 27

As related to fitness, less desirable genes reach an intermediate frequency that cannot be further diluted

Answer 27

overdominant

Question 28

T/F: Hybrid vigor is a positive effect of Gene Combination Value

Answer 28

True

Question 29

Heritabilities of carcass traits in livestock

Answer 29

high

Question 30

T/F: All traits are heritable

Answer 30

false

Question 31

T/F: Pedigree estimates are used in parent EPDs for non-sire genetic evaluations

Answer 31

false

Question 32

T/F: accuracy of selection is highly dependent on heritability

Answer 32

True

Question 33

T/F: if sires are genetically superior to dams, save many female replacements

Answer 33

true

Question 34

T/F: Multi-trait selection increases genetic change by reducing selection intensity

Answer 34

false

Question 35

MOET?

Answer 35

Multiple Ovulation, Embryo Transfer

Question 36

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:

Answer 36

Indicator trait

Question 37

Genotype (G) = Breeding value +

Answer 37

Gene Combination Value

Question 38

Producing ability is the performance potential of an individual for what kind of trait?

Answer 38

Repeated

Question 39

Name two ways to improve Heritability and Repeatability

Answer 39

Environmental Uniformity and accuracy of Data

Question 40

What are the three directly proportional factors that effect Genetic Change

Answer 40

Accuracy of Selection, Selection intensity, and Genetic Variation

Question 41

What factor has an inversely proportional effect on Genetic Change

Answer 41

Generation Interval

Question 42

The risk that the true breeding values of replacements wil be significantly poorer than expected is:

Answer 42

Selection risk

Question 43

What are two common environmental adjustments for heritability and repeatability

Answer 43

age and sex

Question 44

The formula used to account for contemporary group effects is called a

Answer 44

trait ratio

Question 45

For the Quantatative Model

Answer 45

P= (MU) + G + E

Question 46

In threshold traits, "Threshold" is the point where what changes

Answer 46

phenotype

Question 47

A weighted combination of traits defining aggregate breeding value for use in an economic selection index

Answer 47

Breeding objective

Question 48

BLUP stands for

Answer 48

Best Linear Unbiased Predictions

Question 49

What is a Central Test Station

Answer 49

A place where animals (usually males) are asked to perform under same environment

Question 50

What are three types of info found in Sire Summaries?

Answer 50

Animal ID, Misc. info, and Prediction of accuracy info

Question 51

What are three factors affecting Accuracy of Prediction related to Selection index

Answer 51

Heritability, pedigree relationship, # of records, progeny records

Question 52

What are two ways in which accuracy is conveyed in Sire Summaries

Answer 52

Correlation (repeatability), Confidence ranges, probable change (standard error)

Question 53

What is one reason that indirect Selection is performed on correlated traits?

Answer 53

Direct Selection is too expensive to measure; Better accuracy w/indirect; and direct trait is a threshold trait

Question 54

One standard deviation of the mean is a what % probability of occurrence

Answer 54

68%