Genetics 3

Vocabulary flashcards covering key concepts, equations, and definitions in animal genetics, trait types, heritability, selection differential, generation intervals, and breeding strategies.

Molecular Genetics

The branch of genetics concerned with the structure and function of genes.

Applied Genetics

The branch of genetics focused on improving genetic outcomes for the benefit of animals and/or humans.

Population Genetics

The branch of genetics that studies gene frequencies (allele frequencies) within a population and how these frequencies influence genetics.

Quantitative Traits

Traits represented as continuous variables that can be measured numerically, are controlled by many genes, and experience greater environmental influence with variable heritability.

Qualitative Traits

Traits represented as limited variables that can be described or expressed discretely and categorically, are controlled by one or few genes, and experience less environmental influence with greater heritability.

DOHaD Premise

The premise that in-utero environmental interactions with genomic factors influence health and risk of disease later in life.

Phenotype

An observable measure of a trait or performance, determined by the sum of genetics and environmental influences ($\text{PHENOTYPE} = \text{GENOTYPE} + \text{ENVIRONMENT}$).

Heritability

The proportion of phenotypic variation among animals for a particular trait that is due to additive gene effects and can be passed from parent to offspring.

Selection Differential

The phenotypic advantage of the animals chosen to be parents in relation to the overall average for the population.

Generation Interval

The average age of parents at the birth of their offspring that will in turn produce the next generation of breeding animals.

Annual Rate of Genetic Progress

The rate of genetic change per year, calculated as heritability multiplied by selection differential, divided by the generation interval.

In-Breeding

The intensive breeding of close relatives practiced to maintain breed standards and achieve predictability of offspring, which increases homozygosity.

Inbreeding Depression

The loss of vigor, decreased survival, and reduced fertility or performance in offspring resulting from generations of breeding related individuals.

Line-Breeding

A less restrictive form of inbreeding (such as breeding a granddaughter to a grandsire) used to maintain a high genetic relationship to a superior ancestor.

HYPP (Hyperkalemic Periodic Paralysis)

A genetic muscular disease seen in Quarter Horses, American Paint, and Appaloosa breeds caused by a mutation in the $SCN4A$ gene originating from the stallion Impressive.

Out-breeding

The mating of unrelated animals within lines and breeds or between breeds, which increases variation and heterozygosity.

Outcrossing

The mating of individual animals within the same breed that are unrelated for at least 4 to 6 generations.

Crossbreeding

The mating of animals belonging to different breeds to utilize breed complementation and hybrid vigor.

Heterosis

Also known as hybrid vigor, the increased productivity of crossbred progeny above the average of the breeds or lines that are crossed.