Breeding Final Flashcards
expected frequency of the recessive allele for a population in Hardy-Weinberg equilibrium
q
Single-locus genotype consisting of functionally different genes
heterozygote
Reference to offspring that are phenotypically identical to parents of the same phenotype, exclusively
Breed true
Specific location of a gene on a chromosome
Locus
Type of gene action in which the value of the heterozygote is intermediate to the values of the two homozygotes
Incomplete dominance
Expected frequency of the dominant allele for a population in Hardy-Weinberg equilibrium
p^2
Expected frequency of the dominant allele for a population in Hardy-Weinberg equilibrium
p
Type of gene action in which the value of the heterozygote is equal to the value of one of the homozygotes
complete dominance
expected frequency of the homozygous recessive genotype for a population in Hardy-Weinberg equilibrium
q^2
Type of gene action in which the heterozygote is typically superior to the homozygous genotypes
overdominance
Alternative form of a gene
allele
single-locus genotype consisting of functionally similar alleles
homozygotes
Which type of inheritance involves genes located on the sex chromosomes?
sex-linked
Milk production is an example of which type of inheritance
sex-limited
baldness in humans is an example of which type of inheritance?
sex-influenced
Four forces that change gene frequencies
Mutation Selection (controlled) Genetic Drift Migration (controlled)
Assumptions of Hardy-Weinburg and assumptions
Complete dominance -assuming that there is no mutation, selection, migration, random mating, and large populations.
A reduction in performance due to increased homozygosity
inbreeding depression
system of mating in which hyprid vigor and breed complementarity are generated and maintained
crossbreeding system
a breed consisting of two or more component breeds
composite breed
a measure of inbreeding in an individual
Fx
hybrid vigor resulting from having a crossbred dam
HV^m
mating of individuals more closely related than the average of the population
Inbreeding
Hybrid vigor resulting from having a crossbred sire
HV^p
A measure of level of pedigree relationship
Rxy
System of mating in which the relationship between current progeny and an ancestor is maximized while minimizing the inbreeding coefficient
Linebreeding
True/False: a 2-breed specific system yields 100% of both HV^I and HV^M
False
True/False: A 3-breed specific system does not produce its own replacement females
True
True/False: The management difficulty for a 3-breed rotation system is low
False
True/False: a 2-breed rotation system can maximize breed complementarity
False
True/False: A backcross system results in 100% HV^I but 0% HV^m
False
True/False: a composite system results in highly uniform progeny
true
True/False: Alleles that are “alike in state” are by definition “identical by descent”, but alleles that are “identical by descent” are not necessarily “alike in state”
False
An abstract measure of the relationship between two variables
Covariance
A unitless measure of the strength of the linear relationship between two variables
Correlation
The spread of the distribution of a trait in a population, expressed in units of the trait
Standard Deviation
A measure of change in the dependent variable per unit change in the independent variable
Regression
Has a range from 0 to +1
Heritability
Has a range from -1 to +1
Correlation
Truncation Selection
a ratio used to divide selection into “keeper/cullers”
How much progeny look like their parents
heritability
delta G/t
the rate of change in the breeding values of a pop
Obv
the genetic variation
i (in the key equation)
intensity of selection
rBV,BV
accuracy of selection
L
generation interval
Which components are unitless
i rBVBV
Which components can most likely be manipulated by breeders to improve rate of genetic gain
Generation Interval Intensity of Selection Accuracy of Selection
Which estimate (EBV or MPPA) is a prediction of the individual’s performance for the trait of interest in FUTURE records
MPPA
A measure of the strength of the relationship between environmental effects on two traits
Environmental correlation
The weighted combination of traits defining aggregate breeding value used in a selection index
Breeding objective
A trait that may or may not be of importance itself, but is used as a means of selecting on genetically correlated trait
Indicator trait
The change in return expected from a one unit change in performance of a trait
Economic weight
A measure of feed efficiency that is NOT independent of body weight
Average Daily Gain
A measure of the strength of the relationship between performance values for two traits
Phenotypic correlation
A type of indirect selection in which selection is on specific DNA sequences
Marker Assisted Selection
Variation at a single site in DNA
Single nucleotide polymorphism
A level of breeding value that is optimal in either the absolute or practical sense
Selection target
The breeding value of an individual for a combination of traits
Aggregate Breeding Value
a measure of feed efficiency that is independent of body weight
Residual Feed Intake
Reflects correct selection intensity when selecting for multiple, uncorrelated traits
Effective proportion saved
A gene with two or more segregating alleles which have differing effects on a production trait
Quantitative Trait Loci
A measure of the strength of the relationship between breeding values for two traits
Genetic correlation
Pro/Con: Tandem Selection
Easiest method Least effective
Pro/Con: Independent Culling Levels
Can be used at any stage of an animals life Doesn’t “appreciate” genetic merit in one trait if a different trait doesn’t make the cut
Pro/Con: Economic Index
Most effective Hard to calculate
What are two causes of genetic correlations? Specify permanent or temporary
Linkage- temporary Pleiotropy- permanent
Equation for calculating Direct Response to Selection
Equation for multiple uncorrelated traits
Equation for Ratio of Response
Equation for the Standard Deviation of BV
Equation for correlated change
Equation for ratio of response for indirect to direct selection
Prediction Equation
Equation for Wright’s Coefficient of Relationship
Equation for HV (difference in performance of purebreds from crossbreds)
Equation for HV % (difference in performance of purebreds from crossbreds)
Why do genetic predictions regress
Genetic predictions are regressed for the amount of information in order to make them
more or less conservative (i.e. closer to the mean) depending on the amount of
information used in calculation.
What will happen to the weighting factors and accuracies if not accounted for
they will inflate upwards
Factors affecting accuracy of prediction for a repeated trait
number of records
heritability
repeatability
pedigree relationship
Why does pedigree data only provide limited accuravy of prediction
Pedigree data can only provide limited accuracy of prediction because pedigree data
does not account for Mendelian sampling.
Why is progeny data different than pedigree data
Each progeny record provides a measure of the value of the genes that an ind
ividual
transmits. In other words, each
progeny represent
s
an independent sample of genes from
the animal of interest
. This is not true of pedigree information.
Purpose of large-scale evaluation
The purpose of large-scale evaluation is to allow for the genetic comparison of animals in different herds or flocks.
Key equation elements improved by using large-scale genetic evaluation
accuracy
intensity
typical sire summary
Typically comprised of a introductory section which may include an explanation of the data, a glossary of terms, qualifications of a sire to be listed in the summary, a table of genetic parameter estimates (heritabilities and correlations), distributions of predictions within the breed, a table converting accuracies to PC values, and genetic trend graphs. The sire list itself usually includes the animal id, some miscellaneous information (coat color, genetic defects, etc.), and prediction and accuracy measures.
accuracy
measure of the strength of the relationship between true values and their predictions
confidence range
the range of values within which the true value of interest lies
possible change
a measure of accuracy that indicates the potential amount of future change in a prediction
the higher the accuracy, the _______the associated ____________ and possible change
the higher the accuracy, THE SMALLER the associated CONFIDENCE RANGE and possible change
Why do you need to know about the variability about the trait with accuracies
With accuracies, you do not need to know anything about the variability about the trait in order to interpret the value, which is not true about confidence ranges or possible change values. However, confidence ranges and possible changes are more graphic and can be more informative indicators of the reliability of a prediction.
Why is male selection more important than female selection
sire selection drives genetic change
more accessible than dams
