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Flashcards in Exam 2 Deck (54):
1

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

2

Fitness

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

3

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

4

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

5

Progeny Difference

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

6

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

7

Phenotypic Correlation

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

8

Genetic Correlation

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

9

Contemporaries

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

10

Genetic Trend

Change in the mean breeding value of a population over time

11

Heritability

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

12

Repeatability

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

13

Accuracy

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

14

Selection Target

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

15

Producing ability

The performance potential of an individual for a repeated trait

16

What are the three methods of multiple-trait selection

Tandem Selection
Independent Culling Levels
Economic Selection Index

17

Two types of Genetic Prediction discussed in class:

Selection index and BLUP

18

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

True

19

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

True

20

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

False

21

Used to compare animals using data from genetically diverse groups

BLUP

22

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

True

23

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

false

24

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

True

25

T/F: Threshold traits are polygenic

True

26

Which traits have low heritabilities (

fertility

27

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

overdominant

28

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

True

29

Heritabilities of carcass traits in livestock

high

30

T/F: All traits are heritable

false

31

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

false

32

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

True

33

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

true

34

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

false

35

MOET?

Multiple Ovulation, Embryo Transfer

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:

Indicator trait

37

Genotype (G) = Breeding value +

Gene Combination Value

38

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

Repeated

39

Name two ways to improve Heritability and Repeatability

Environmental Uniformity and accuracy of Data

40

What are the three directly proportional factors that effect Genetic Change

Accuracy of Selection, Selection intensity, and Genetic Variation

41

What factor has an inversely proportional effect on Genetic Change

Generation Interval

42

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

Selection risk

43

What are two common environmental adjustments for heritability and repeatability

age and sex

44

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

trait ratio

45

For the Quantatative Model

P= (MU) + G + E

46

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

phenotype

47

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

Breeding objective

48

BLUP stands for

Best Linear Unbiased Predictions

49

What is a Central Test Station

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

50

What are three types of info found in Sire Summaries?

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

51

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

Heritability, pedigree relationship, # of records, progeny records

52

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

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

53

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

54

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

68%