The Evolution of Populations Vocabulary

Vocabulary flashcards covering key concepts from Topic 6: The Evolution of Populations, including genetic variation, modes of natural selection, genetic drift, gene flow, and mechanisms of balancing selection.

Microevolution

A change in allele frequencies in a population over generations.

Gene Pool

All the alleles present in all individuals in a population.

Allele

Different forms of a gene, corresponding to different DNA sequences in each form.

Nonheritable Variation

Phenotypic variation that does not result from genetic differences, but rather from environmental influences such as diet.

Mutation

A random change in the nucleotide sequence of DNA that creates new alleles.

Point Mutation

A change in one base in a gene.

Non-adaptive Evolution

Any change in allele frequency that does not lead a population to become more adapted to its environment.

Relative Fitness

The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals.

Directional Selection

A mode of natural selection that favours individuals at one end of the phenotypic range.

Disruptive Selection

A mode of natural selection that favours individuals at both extremes of the phenotypic range over intermediate phenotypes.

Stabilizing Selection

A mode of natural selection that favours intermediate variants and acts against extreme phenotypes.

Genetic Drift

Unpredictable, random changes in allele frequencies in a population from one generation to the next, which can lead to a loss of genetic variation.

Founder Effect

A type of genetic drift that occurs when a few individuals become isolated from a larger population, establishing a new population with different allele frequencies.

Bottleneck Effect

A sudden reduction in population size due to an environmental change, resulting in a gene pool that may no longer reflect the original population.

Gene Flow

The transfer or movement of alleles among populations due to the movement of fertile individuals or gametes.

Balancing Selection

Natural selection that maintains stable frequencies of two or more phenotypic forms in a population.

Frequency-Dependent Selection

A type of selection in which the fitness of a phenotype declines if it becomes too common in the population, favouring whichever phenotype is less common.

Heterozygote Advantage

A situational advantage occurring when heterozygous individuals at a particular locus have a higher fitness than both types of homozygous individuals.

Extirpation

The local extinction or disappearance of a species from a particular geographical area, reducing species genetic diversity.