ANSC 3500 DIY Exam 2

What is true about covariation?

A positive covariance between birth weight (BW) and weaning weight (WW) means that calves with increased BW will also have increased WW.

__________measures the strength (consistency and reliability) of the _______________ between two traits.

Correlation, relationship

True or False. A regression equation is a mathematical equation that allows us to predict the best combination of traits to be selected.

False

True or False. Estimated breeding value (EBV) is a prediction of the breeding value of an individual as a genetic parent due to dominance effects that are transmissible to the progeny.

False

True or False. The BV of a sire can be calculated as twice the expected difference in its progeny

True

True or False. A parent transfer ¾ of its genes to the offspring. ½ is due to additive effects and ¼ is due to the dominance effect.

False

True or False. Dominance and epistasis are the main components of the breeding value.

False

The effect of a gene independent of the effect of the other gene at the same locus (dominance) and the effects of genes at other loci (epistasis). This is an example of:

Additive effect

True or False. An animal's breeding value for a trait is simply the sum of the independent effects of that animal's gene for a locus and at all other loci affecting the trait.

True

True or False. The gene combination value is not transmissible from parent to offspring.

True

For genetic change to be possible in a trait in a population, what must be present within this population?

Variation

True or False. On average, only half of the dominance genetic value is transmitted from parent to offspring.

False

True or False. EPDs can not be compared across breeds without adjustment.

True

True or False. The BV of a sire can be calculated as twice the difference in its progeny.

True

True or False. On average, only half of the genotypic value is transmitted from parent to offspring.

False

Assuming that the dam's BV = +40 kg and the sire's BV = +60 and the population average is 250 kg. Which is the expected performance of the offspring?

300 kg

True or False. The progeny difference is one-half of the additive genetic value.

True

What is true about genetic variation

Genetic variation is the source of genetic change, Is affected by selective breeding

True or False. Epistatic effects depend on the combination of genes at different loci. Due to that, offsprings inherit only ½ of the genotypic value from each parent.

False

__________is the value of an individual's alleles to its progeny's performance, while _______________ is the value of an individual's genes to their own performance.

Expected progeny difference (EPD), Breeding value

____________ market breeding potential, so __________ market breeding potential,

Seed stocker, Breeding value

____________ is the part of an individual's ________________ value that is due to the effects of gene combinations (dominance and epistasis)

GCV, genotypic

True or False. The heritability for reproductive traits ranges from medium to high.

False

It is a measure of the strength of the relationship between the breeding value and the phenotype

Heritability

What is the range of values for a h2 estimate?

0 to 1

1 multiple choice option

True or False. Because heritability and correlation share similar mathematical properties, heritability values range from -1 to + 1.

False

True or False. Heritability is an estimate of the proportion of total phenotypic variation between individuals for a given trait that is due to differences among genotypes of individuals in the population.

True

True or False. If a trait is strongly influenced by variations in the environment, the trait's heritability will be high in a population in which environmental conditions undergo great changes.

False.

True or False. When the heritability is high, the correlation between the breeding value and the phenotype of the individual is also high. Therefore, the observation of the phenotype is a good indicator of the breeding value of the individual.

True

True or False. When the trait has a low heritability, its improvement largely depends on the environment.

True

True or False. Carcass traits have low heritability values.

False

True or False. In highly heritable traits, much of the variation in the phenotype is due to environmental differences.

False

True or False. Considering that some traits are strongly influenced by environmental effects, it is correct to say that the heritability of a trait will be low in the case of populations that inhabit places that suffer great environmental variations.

True

True or False. Heritability is used to compare animals, within a breed, as to the performance of their future progeny.

False

True or False. A heritability of 0.7 indicates that 30% of the trait is determined by environmental effects.

False

True or False. The square root of broad sense heritability is the correlation between the phenotypic values with the genotypic values.

True

True or False. The heritability of a trait is constant, regardless of the environment. However, differences in the prediction methods may lead to differences in heritability estimates.

False

True or False. The narrow sense heritability is the square root of the correlation between the phenotypic values with the additive genetic values.

True

True or False. If the heritability of a trait is high, breeding values for the trait will be high also.

True

True or False. Selective breeding for traits with high heritability leads to more accurate BV predictions and faster genetic progress.

True

True or False. Repeatability is a measure of the strength of the relationship between repeated records (repeated phenotypic values) for a trait in a population

True

True or False. When repeatability is high, a single record of performance of an animal, is on average, a good indicator of an animal's producing ability

True

True or False. Repeatability is important for making culling decisions. Thus, animals with low performance for a trait with high repeatability can be culled down.

True

True or False. When repeatability is high, animals with poor performance can be culled based on their first record.

True

True or False. When repeatability is low, animals with poor performance can be culled based on their first record.

False

True or False. Low repeatability leads to more accurate predictions, as we make fewer mistakes in the replacement selection.

False

True or False. The repeatability of fertility, either as the number of lambs born or weaned, is low. This means that culling ewes based on their first ewe performance will produce little lifetime gain.

True

True or False. Heritability and repeatability are related population parameters important for culling decisions.

True

True or False. Because repeatability is a fixed population parameter, it is not possible to change it through selective breeding.

False

True or False. Environmental effects common to repeated measures on an individual are defined as permanent.

True

True or False. Unlike heritability, repeatability measures are less affected by the environment.

False

True or False. Repeatability is a ratio of genotypic and permanent environmental variances by the total phenotypic variance

True

True or False. Repeatability can be used to predict future records for an animal based on its previous records.

True