Chapter 24 Study Guide: Quantitative Traits and Heritability

Vocabulary flashcards covering key concepts: quantitative traits, variance components, and heritability from the provided notes.

Quantitative traits

Traits that show a continuous distribution and are influenced by multiple genes (polygenic) and environmental factors; they vary over a range of values rather than into discrete categories.

Continuous distribution

A pattern where trait values form a continuum rather than distinct, separate categories.

Polygenic

Traits are influenced by many genes that collectively contribute to the phenotype.

Environmental factors

Non-genetic influences that affect trait expression and contribute to phenotypic variation.

Height (example of a quantitative trait)

A quantitative trait influenced by both genetic makeup and environmental factors such as nutrition.

Total variance

The overall phenotypic variance in a population, equal to genetic variance plus environmental variance.

Genetic variance

The portion of total variance due to genetic differences; can be subdivided into additive variance and dominance variance.

Additive variance

Variance attributable to the additive effects of individual alleles.

Dominance variance

Variance arising from interactions between alleles at the same locus (dominance).

Environmental variance

Variance due to non-genetic factors such as climate, soil quality, and management practices.

Heritability

A measure of the proportion of phenotypic variance in a population attributable to genetic differences; values near 1 indicate a strong genetic basis, but it does not mean the trait is fully genetically determined.

Implication of high heritability for breeding

High heritability values can guide selective breeding by indicating traits that can be reliably passed on to offspring.