selection plant breeding

Genetic Gain

The increase in performance of a trait achieved through artificial genetic improvement programs, measured after one generation.

Genetic Improvement Programs

Programs aimed at enhancing specific traits through selective breeding utilizing methods from quantitative genetics.

Heritability

The proportion of phenotypic variance attributable to genetic variance, important for predicting response to selection.

Response to Selection

The change in phenotypes across generations due to natural or artificial selection, influenced by genetic variation and heritability.

Selection Intensivity

The ratio of selection differential to phenotypic standard deviation, indicating how strongly a trait is being selected for in a population.

Breeder's Equation

The equation R = h²S, which relates selection response to heritability and selection differential.

Selection Differential (S)

Quantifies the difference in phenotype between selected individuals and the overall population.

Phenotypic Standard Deviation (σp)

A measure of variation within a population's traits, essential for calculating selection intensity.

Genetic Advance

The expected improvement in a trait due to selection over generations, dependent on selection intensity and heritability.

Quantitative Genetics

The field that utilizes statistical methods to predict genetic change by measuring traits and their inheritance patterns.

Artificial Selection

Human-driven selective breeding that mimics natural selection to rapidly change traits in species.

Narrow-Sense Heritability (h²)

The proportion of phenotypic variance attributable to additive genetic variance, calculated as h² = R/S.

Selection Intensity (i)

Defined as the ratio of selection differential (S) to phenotypic standard deviation (σp): i = S/σp.

Estimating Response to Selection

The process of determining the change in phenotype across generations due to genetic selection, influenced by heritability and selection differential.

Genetic Variation

Essential for both natural and artificial selection; it determines the potential for evolutionary change.

Natural Selection

The mechanism where certain genotypes are favored in reproduction, leading to adaptive changes in populations.

Artificial Selection

A human-driven mechanism used to accelerate desired traits in species, as seen in domestic animals.

Example of Genetic Gain Calculation

Using a cotton variety example, genetic gain (G) can be calculated based on selection differential (S), selection intensity (i), and heritability.