Population Genetics and Heritability

Flashcards covering key concepts from the lecture on population genetics, qualitative and quantitative variation, heritability, and their implications in biology.

Qualitative Variation

Traits that vary qualitatively, with a small number of distinct phenotypes.

Examples of Qualitative Traits

Snow geese feather color (white or blue) and pea plant seed shape (round or wrinkled).

Quantitative Variation

Traits that show a continuous range of phenotypes, often not easily categorized into discrete bins.

Polygenic Traits

Traits controlled by more than one gene, leading to complex phenotypic variation.

Heritability (H²)

The fraction of phenotypic variation in a population due to genetic variation.

Phenotype vs Genotype

Phenotype is the expressed trait, while genotype is the underlying genetic makeup.

Environmental Effects on Traits

Environmental conditions can influence phenotypic expression, complicating genotype-phenotype relationships.

Directional Selection

Natural selection that favors individuals at one end of a phenotypic spectrum.

Stabilizing Selection

Natural selection that favors the average phenotype and reduces variation.

Disruptive Selection

Natural selection that favors individuals at both extremes of the phenotypic spectrum.

Heritability Estimation

Using parent-offspring resemblance to estimate the heritability of a trait.

Counterintuitive Heritability

High heritability in a population does not imply genetic differences between populations with phenotypic differences.

Genotype-Phenotype Complexity

The relationship between genotype and phenotype is more complex in quantitatively varying traits.

Example of Polygenic Traits

Human height, where multiple genes and environmental factors affect the trait's expression.

Genetic Variation (VG)

The portion of phenotypic variation in a population attributed to genetic differences.

Environmental Variation (VE)

The portion of phenotypic variation in a population attributed to environmental differences.