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51 Cards in this Set
- Front
- Back
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What is the basic genetic model? |
P=μ+G+E P= phenotypic value μ= population mean G= genotypic effect E= environmental effect |
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What is the definition of quantitative genetics? |
The branch of genetics concerned with influences in, measurements of, relationships among, genetic prediction for, and rate of change in quantitative traits |
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Phenotypic Value (P) |
Measure of performance for a trait in an individual- performance record |
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Population mean (μ) |
Average phenotypic value of all the individuals in a population |
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Genotypic Value (G) |
Effect of an animal's genes (singly and in combination) on its performance for a trait |
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Environmental Effect (E) |
The effect external(non-genetic) factors have on animal performance |
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Value (in animal breeding) |
Measure applied to an individual as opposed to a population |
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Population measure |
Any measure applied to an individual as opposed to an individual |
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Population Parameters |
A true population measure |
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Sample statistic |
An estimated population measure |
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Normal distribution |
The statistical distribution that appears graphically as a symmetric, bell shaped curve |
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Variation |
Differences among individuals within a population |
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Variance |
Mathematical measure of variation |
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Standard deviation |
Mathematical measure of a variation that can be thought of as an average deviation from the mean |
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Variable |
Quantity that can take in different numerical values |
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Covariation |
How two traits/values vary together in population |
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Covariance |
The expected or average change in one variable (y) per unit change in another (x) |
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Breeding value (1st definition) |
Value of an individual as a (genetic) parent |
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Independent gene effect |
Effect of a gene independent of the effect if the other gene at a locus or at other loci |
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Breeding value (2nd definition) |
Part of an individual's genotypic value (G) due to independent/transmittable gene effects |
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Estimated breeding value |
Prediction of a breeding value |
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Expected Progeny Difference (EPD) |
Predicted difference or estimated transmitting ability (ETA) |
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Additive gene effect |
Independent gene effecrs |
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Additive genetic value |
Breeding value |
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Gene combination value (gcv) |
Part of an individual's genotypic value due to effects of gene combinations (dominance and epistasis) and cannot be transmitted from parent to offspring |
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Gene combination effects |
Effect of a combination of genes |
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Nonadditive gene effects |
Gene combination effects |
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Nonadditive genetic value or non additive value |
Gene combination value |
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Repeated trait |
Trait for which individuals commonly have more than one performance record |
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Producing Ability (PA) |
Performanxe potential of an individual for a repeated trait |
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Permanent environmental effect (Ep) |
Environmental Effect that permanently influences an individual's performance for a repeated trait |
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Temporary environmental effect (Et) |
Environmental Effect that influences a sibgle performance record or an individual, but not permanently affect the performance potential for a repeated trait |
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Heritability (h2) |
A measure of the strength of the relationship between performance (phenotypic values) and breeding values for a trait in a population |
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Heritability in the broad sense (H2) |
A measure if the strength of the relationship between performance (phenotypic values) and genotypic values for a trait in a population |
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Repeatability |
Measure of the strength of the relationship between repeated phenotypic values for a trait in a population |
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Selection |
The process that determines which individuals become parents, the number of offspring, and length of time remaining in the population |
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Natural selection |
Selection independent of human control |
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Artificial selection |
Selection dependent on human control |
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Replacement selection |
Process that determines which individuals will become parents for the first time |
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Culling |
Process that determines which parents will no longer become parents |
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Key equation |
Equation relating the rate of genetic change resulting from selection to four factors |
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Accuracy of selection |
Measure of strength of the relationship between true breeding values and their predictions for a trait under selection |
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Selection intensity |
Measure of how "choosy" breeders are in deciding which individuals are selected |
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Genetic variation |
Variability of breeding values within a population for a trait under selection |
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Generation interval |
Amount of time required to replace one generation with the next |
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Rate of genetic change/response to selection |
Rate of change in the mean breeding value of a population caused by selection |
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Selection Criterion (SC) |
An EPV, EPD, phenotypic value, or other piece of information forming the basis for selection decisions |
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Selection differential |
Difference between the mean selection criterion of those individual selected to be parents and the average selection criterion of all potential parents, expressed in units of the selection criterion |
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Truncation selection |
Selection on the basis of a distinct division in the selection criterion above which individuals are kept and below which they are rejected |
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Proportion saved |
number of individuals chosen to be parents as a proportion of the number of potential parents |
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Effective proportion saved |
In selection- a value that, when substituted for actual proportions saved, reflects correct selection intensity |
