Exam 2 Flashcards
If the variance in the temporary environment decreases, heritability also decreases. (T/F)
False
All other factors held constant. if a producer decides to keep back his top 20% rather than the top 30% of females for breeding, he decreases his selection intensity. (T/F)
False
Adjusting phenotypic measurements for biological effects known to influence a trait helps to increase our estimate of repeatability. (T/F)
True
Breeding values for polygenic traits cannot be directly measured. (T/F)
True
If two traits are positively correlated, selecting on one will necessarily have a favorable impact on the other. (T/F)
False
Pleiotrophy, which is defined as a single trait being attributed to the action of multiple loci, is one reason some traits are correlated. (T/F)
False
In the genetic model, G includes all genetic factors an animal reliably passes on to its progeny. (T/F)
False
Features of heritability include:
a) it tends to be stable in value for a trait within a population (e.g., within a breed)
b) when heritability for a trait is low, it should never be included in a breeding program
c) its value is estimated from the regression of producing ability on performance
d) both 1 and 3
A
With respect to the key equation, if nothing else changes, decreasing the generation interval:
a) decreases heritability
b) increases the anticipated rate of genetic improvement
c) decreases replacement rate
d) decreases selection intensity
e) both 2 and 3
B
A trait with a heritability of 0.3 and a repeatability of 0.4, is measured on a ram and five of his full-siblings. The common environment effect (c2) is 0.2. The accuracy of prediction of the ram’s breeding value for the trait would increase if:
a) repeatability was instead 0.5
b) the records were on his progeny instead of from full-siblings
c) the common environment effect was zero
d) both 2 and 3
e) all of 1, 2, and 3
C
An individual’s most probable producing ability:
a) can never be negative
b) increases with increased variance in a temporary environment
c) is dependent upon the regression of producing ability on generation interval
d) increases if the resemblance among relatives increases
e) increases as the number of repeated records on that individual increases
E
Genomic selection:
a) relies upon the principle of linkage disequilibrium to associate variation with phenotypic variance
b) reduces the amount of phenotype data necessary for accurate prediction of breeding values
c) can improve the rate of genetic change by allowing individuals to be selected earlier, thus increasing the generation interval
d) both 1 and 2
e) both 1 and 3
A
