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