Animal Breeding Exam 3 Retake Flashcards
Selection Index
A linear combination of phenotypic information and weighting factors that is used for genetic prediction when performance data come from genetically similar contemporary groups
What are the 3 types of information used to calculate genetic predictions?
- Own performance data
- Pedigree data
- Progeny data
Regression
mathematical process that causes genetic predictions to be more or less conservative (closer to the mean) depending upon the amount of information that is available.
What 4 factors is amount of regression based on?
- Number of records
- Repeatability of traits
- Heritability of traits
- Pedigree information
Common environment effect
An increase in similarity of performance of family members caused by sharing a common environment.
Explain common environment
Relatives performances are typically similar because they have genes in common. Full siblings share a common environment because they have same parents because of this performance records of full sibs provide less information than expected. Important in liter bearing species
BLUP (Best Linear Unbiased Prediction)
Method of genetic prediction that is particularly appropriate when performance data come from genetically diverse contemporary groups
Blups allows us to look at genetically different cattle from
Different farm, different decades, and different contemporary groups
T or F. Blup can account for changes in genetic trend
True
Direct component or effect
Effect of an individuals genes on its performance
Maternal component or effect
The effect of genes in the dam of an individual that influence the performance of the individual through the environment provided by the dam
Large scale genetic evaluation
The genetic evaluation of large populations, typically entire breed
Sire summaries
A list of genetic predictions, accuracy values, and other useful information about sires in a breed.
Accuracy measures
Strength of the relationship between true values and their predictions
Parent EPD
An EPD for an animal with progeny data
Nonparent EPD
A genetic prediction based solely on pedigree data
Interim EPD
An updated EPD that is calculated between BLUP analyses and incorporates new information
Nucleus Breeding Scheme
A cooperative breeding program in which elite animals are concentrated in a nucleus herd or flock and superior germ plasm is then distributed among cooperating herds or flocks.
Correlated response to selection
Genetic change in one or more traits resulting from selection for naother
Pleiotropy
The phenomenon of a single gene affecting more than one trait
Types of correlations
Genetic, Phenotypic, Environmental
Genetic correltion
measure of the strength of the relatioship bectween breeding values for one trait and breeding values for another
Phenotypic correlation
A measure of the strength of the relationship between performance in one trait and performance in another trait
Environmental correlation
A measure of the strength of the relationship between environmental effects on one trait and environmental effects on another trait
Magnitude
Is this a strong relationship for a weak relationship
What are the 3 ways to classify correlations
Strength (strong or weak)
Sign (pos or neg)
Favorable or unfavorable
Direct response to selection
Genetic change in a trait resulting from selection for that trait
Direct selection
Selection for a trait as a means of improving that same trait
Indirect selection
Selection for one trait as a means of improving a genetically correlated trait
When can indirect selection be helpful
For a trait that is difficult or expensive measure
Selection intensity
Selecting for a continuous trait may have greater selection intensity than the trait of interest if the trait of interest is a threshold trait
Indicator traits
A trait that may or may not be important in itself, but is selected for as a way of improving some other genetically correlated trats
Single trait selection
selection for a single trait
Multiple trait selection
Selection for more than one trait
Aggregate breeding value OR net merit
The breeding value of an individual for a combination of traits
Tandem Selection
Selection for one trait then another
Easiest form of multiple selection
Selection target
A level of breeding value considered optimal in an absolute or practical sense
Independent culling levels
Minimum standards for traits undergoing multiple trait selection. Animals failing to meet any one standard are rejected regardless of merit in other traits
Economic selection indexes
An index or combination of weighting factors and genetic information either phenotypic data or genetic predictions on more than one trait. Economic selection indexes are used in multiple trait selection to predict aggregate breeding value
Selection indexes
A single number that predicts the BV of an individual for a weighted combination of traits
Economic weight
the change in aggregate breeding value due to an independent one unit increase in performance of a trait
Phenotypic selection index
a form of economic selection index used with phenotypic selection. In the classic form of phenotypic index, the traits in the index are identical to the traits in the breeding objective
What multiple trait selection method has the greatest chance of increasing the aggregate breeding value?
Economic selection index
