Lesson 21: Mechanisms of Evolutionary Change

Allele Frequencies

The proportion of a specific allele among all alleles for a given gene in a population.

Artificial Selection

The intentional breeding of organisms by humans to favor desirable traits.

Bottleneck Effect

A sharp reduction in population size due to environmental events or disasters, causing loss of genetic diversity.

Epistasis

Interaction between genes where one gene masks or modifies the effect of another.

Evolution

Change in the genetic composition of populations over generations.

Fitness

An organism’s ability to survive and reproduce, contributing its genes to the next generation.

Founder Effect

Reduced genetic variation when a new population is established by a small number of individuals.

Genotype

The genetic makeup of an organism (its set of alleles).

Phenotype

The observable traits of an organism, resulting from genotype and environment.

Gene Flow

Movement of alleles between populations through migration or interbreeding.

Genetic Drift

Random changes in allele frequencies in a population, especially in small populations.

Genetic Variation

Differences in DNA sequences among individuals in a population.

Hardy-Weinberg Equilibrium

A theoretical state where allele and genotype frequencies remain constant across generations in the absence of evolutionary forces.

Mutation

A change in DNA sequence that can introduce new genetic variation.

Natural Selection

Process where individuals with advantageous traits survive and reproduce more successfully.

Nonrandom Mating

Mating that is not by chance, often influenced by traits, location, or social factors.

Polymorphic Variation

The occurrence of two or more distinct phenotypes within a population.

Population

A group of individuals of the same species living in the same area and interbreeding.

Population Genetics

The study of genetic variation within populations and how it changes over time.

Selection

Any process that favors certain traits over others, influencing survival and reproduction.