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Flashcards in Exam 3 Deck (43)
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1

Population measure

Any measure applied to a population as opposed to an individual

2

Population parameter

A true population measure (as opposed to an estimated). Ex. Means, variances, and standard deviation; true correlations between traits

3

Sample statistic

An estimate of a populations parameter

4

Normal distribution

A statistical distribution that appears graphically as a symmetric, bell-shaped curve.

5

Mean

The arithmetic average

6

Variation

Differences among individuals within a population

7

Variance

(o^2)
A mathematical measure of variation

8

Standard deviation

(o)
A mathematical measure of variation that can be thought of as an average deviation from the mean. The square root of the variation

9

Variable

Any quantity that can take on different numerical values. All elements (except Mu) of the genetic model for quantitative traits are considered variables

10

Covariation

How two traits or values vary together in a population

11

Covariance

cov(X,Y)
The basic measure of covariation

12

Correlation coefficient

r
(x,y)
A measure of the strength of a relationship between two variables

13

Phenotypic correlation

r
(Px,Py)
A measure of the strength of the relationship between performance in one trait and performance in another trait

14

Genetic correlation

r
(BVx,BVy)
A measure of the strength of the relationship between breeding values for one trait and breeding values for another trait

15

Environmental correlation

r
(Ex,Ey)
A measure of the strength of the relationship between environmental effects on one trait and environmental effects on another trait

16

Regression coefficient

b
(y*x)
The expected or average change in one variable (Y) per unit change in another (X)

17

True value

An unknown, underlying attribute that affects animal performance. Examples include breeding value, progeny difference, gene combination value, producing ability, and environmental effects

18

Predicted value

A prediction of a true value. Ex EBV or BV; EPD or PD; MPPA or PA

19

Prediction equation

A mathematical equation used to calculate a predicted value based on phenotypic data

20

Heritability

h^2
A measure of the strength of the relationship between performance and breeding values for a trait in a population

21

Heritability in the broad sense

H^2
A measure of the strength of the relationship betel next performance (phenotypic values) and genotypic values for a trait in a population

22

Repeatability

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

23

Contemporary group

A group of animals that have experienced a similar environment with respect the expression of a trait. Typically perform in the same location, same sex, similar age, managed alike

24

Contemporary group effect

E
cg
An environmental effect common to all members of a contemporary group

25

Trait ratio

An expression of relative performance— the ratio of an individual’s performance to the average performance of all animals in the individual’s contemporary group

26

Key equation

The equation relating the rate of genetic change resulting from selection to four factors: accuracy of selection, selection intensity, genetic variation, and generation interval

27

Accuracy of selection

r. ^
(BV, BV)
A measure of the strength of the relationship between true breeding values and their predictions for a trait under selection

28

Selection intensity

(i)
A measure of how “choosy” breeders are in deciding which individuals are selected
The difference between the mean selection criterion of those individuals selected to be parents and the average selection criterion of all potential parents, expressed in standard deviation units

29

Genetic variation

o
(BV)
In the context of the key equation for genetic change, variability of breeding values within a population for a trait under selection

30

Generation interval

L
The amount of time required to replace on generation with the next
In a closed population, the average age f presents when their selected offspring are born