Evolutionary Change in Populations Flashcards

Vocabulary practice flashcards for Ch. 18 & 19 covering population genetics, Hardy-Weinberg equilibrium, evolutionary mechanisms, and types of selection.

Population Genetics

The study of genetic variability within a population and the evolutionary forces that act on it.

Population

A group of individuals of one species living in the same geographic area at the same time.

Gene Pool

All the alleles for all genes present in a population.

Genotype Frequency

The proportion or percentage of a particular genotype present in a population.

Phenotype Frequency

The proportion or percentage of a particular phenotype observed in a population.

Allele Frequency

The proportion or percentage of a specific gene allele within a population's gene pool.

Hardy-Weinberg Equation

The mathematical equations $p^2 + 2pq + q^2 = 1$ and $p + q = 1$ used to describe genotype and allele frequencies in a population at genetic equilibrium.

Hardy-Weinberg Principle

The principle stating that allele frequencies in a population remain constant across generations (genetic equilibrium) provided there are no mutations, random mating, large population size, no gene flow, and no natural selection.

Microevolution

Generation-to-generation changes in allele or genotype frequencies within a population when one or more Hardy-Weinberg equilibrium conditions are not met.

Mutation

Unpredictable changes in DNA that serve as the ultimate source of new alleles and increase genetic variability within a population.

Assortative Mating

A form of non-random mating where individuals select mates based on specific observable phenotypes.

Inbreeding

The mating of genetically similar individuals within a population.

Inbreeding Depression

A decline in biological fitness where inbred individuals exhibit lower survival and reproduction rates compared to non-inbred individuals.

Genetic Drift

Random changes in allele frequencies within a population that tend to decrease genetic variation, occurring most prominently in small populations.

Bottleneck

A sudden, dramatic reduction in population size caused by adverse environmental factors or events.

Founder Effect

A form of genetic drift that occurs when a few individuals establish a new population with allele frequencies different from the original population.

Gene Flow

The transfer or movement of alleles between different populations.

Directional Selection

A mode of natural selection that favors individuals expressing one extreme phenotype, causing a shift in the overall phenotypic distribution of the population over time.

Stabilizing Selection

A mode of natural selection that favors intermediate phenotypes and selects against extreme phenotypes, reducing overall variation.

Disruptive Selection

A mode of natural selection that favors individuals at both extreme ends of the phenotypic spectrum over intermediate phenotypes.

Achillea millefolium Geographic Variation

Geographic variation in yarrow plant height across the Sierra Nevada Range, demonstrating a decrease in mean plant height as elevation increases.

Sickle-Cell Hemoglobin Mutation

A point substitution on chromosome 11 in the beta-hemoglobin gene where nucleotide codon $\text{GAG}$ mutates to $\text{GTG}$, substituting glutamic acid ($\text{Glu}$) with valine ($\text{Val}$) at amino acid position 6.