Animal Breeding Terms

Heritability

Heritability

A measure of the strength of the relationship between performance and breeding value for a trait in a population

Additive Gene Effect

The contributions of the final phenotype from more than one gene, or from alleles of a single gene, that combine in a way that the sum of their effects is equal to the sum of their effect individually (no dominance)

Sex-linked inheritance

The gene linked to sex chromosomes

Sex-limited inheritance

Phenotypic expression limited to one particular sex

Sex-influenced inheritance

Modes of gene expression differ between males and females

Test mating

A mating designed to reveal genotype of an individual for a small number of loci

Repeatability

The measure of the strength of a relationship between repeated records for a trait in a population

Correlation

The measure of the strength of the relationship between two variables

Dominance and the 4 types of dominance

One member of an allele pair of gene that has the ability to exclude the expression of the other member.

No Dominance

Complete Dominance

Partial Dominance

Over Dominance

Breeding Value

The value of an individual as a “genetic” parent. The genotypic value that can be transmitted from parent to offspring

Variance

The measure of variation/difference of individuals within a population

Genetic selction

Information on the genotype/performance of pedigree or progeny of an individual

Genomic selection

Selection based on the genomic information plus relatives information

Hardy-Weinberg Equilibrium law

Large random-mating population with no selection, mutation, or migration. Gene & genotypic frequencies are constant through generations.

Simple relationship between gene and genotypic frequencies.

Accurcy of estimated breeding value

A measure of the strength of the relationship between true breeding values and their prediction

What is a gene

A basic physical unit of heredity consisting of a DNA sequence at a specific location on a chromosome that has a function

Gene Frequency

The ratio of a particular allele to the total of all other alleles of the same gene in a given population

Coefficient of Variation

The measure of relative variability.
Ratio of standard deviation to the mean

Regression

The average/expected change in one variable (y) per unit of change in the other (x)

Genotypic Frequency

The number of individuals with a given genotype divided by the total number of individuals in the population

BLUP

Best Linear Unbias Prediction

A method of genetic evaluation for estimated breeding value

Covariance

The measure of the joint variability of two variables

Epistasis

The effect between genes of different loci

Outbreeding

The breeding of non-related individuals

Inbreeding

The breeding of related or genetically similar individuals

Positive assortative mating

The mating of individuals with similar phenotypes

(Tallest with Tallest)

Decrease uniformity

Increase genetic variation and genetic gain in the offspring of the population

Negative assortative mating

The mating of individuals with dissimilar phenotypess

(Tallest with shortest)

Increase uniformity

Decrease genetic variation and genetic gain in the offspring of the population