Heritability and Repeatability

Question 1

Define Heritability (r^2).

Answer 1

The extent of differences observed in animal performance for a trait that is due to variation in genetics within a population.

Question 2

If heritability is __________, then the performance, on average, is a __________ indicator of an animal’s performance.

Answer 2

high ; good

OR

low ; poor

Question 3

The three main causes of genetic/genotypic correlation are:

Answer 3

Linkage
GEI
Pleiotropy

Question 4

What are the two types of heritability?

Answer 4

Broad Sense
Narrow Sense

Question 5

Which type of heritability is better for transmissible traits?

Answer 5

Narrow Sense

Question 6

What are the units for heritability?

Answer 6

There are no units!

Question 7

Define the range for heritability.

Answer 7

0 to 1

Question 8

True or False. Heritability is the proportion of a phenotype that is passed on.

Answer 8

False.

Question 9

True or False. Heritability can change.

Answer 9

True

Question 10

True or False. Low heritability means traits are not determined by genes.

Answer 10

False

Question 11

Formally define repeatability.

Answer 11

Measures the degree of association (strength) between repeated records of the same animal for phenotypes measured more than once.

Question 12

Define environment.

Answer 12

All of the non-genetic factors to which an individual is subjected to or experienced from the formation of zygote to birth and till death.

Question 13

Define permanent environmental effect(s).

Answer 13

Environmental effects on an individual’s phenotype that are constant across (or common to) repeated measures on that individual.

Question 14

Define temporary environmental effect(s).

Answer 14

Environmental effects on an individual’s phenotype- which influences only a single observation on the individual (by chance).

Question 15

Repeatability ranges from ____ to _____, but almost never goes below _____.

Answer 15

-1 ; 1 ; 0

Question 16

If a trait is _______ repeatable, then one record, on average, is a ___________ indicator of producing ability (PA).

Answer 16

highly ; good

OR

lowly ; poor

Question 17

How can one increase h^2 and r?

Answer 17

Manage environmental effects to be consistent.

Question 18

Can we predict an animal’s production?

Answer 18

Yes!

Question 19

What variables are needed to calculate an animal’s production (PA)?

Answer 19

r, repeatability
n, number of records
Pi, individual’s phenotype for a specific record
u, phenotype average

Question 20

What is producing ability (PA)?

Answer 20

The performance potential of an individual for a repeated trait.