Topic 1.3 – Natural and Artificial Selection

Vocabulary flashcards covering key terms from Topic 1.3 on how natural and artificial selection, mutations, and human activities influence genetic diversity and species change.

DNA Mutation

A permanent change in an organism’s genetic material; the primary source of new genetic variation.

Genetic Diversity

The variety of alleles present within a population, produced largely by mutations.

Allele

One of two or more alternative forms of a gene inherited from parents.

Selective Advantage

A genetic trait that improves an organism’s chance of survival and reproduction in a changing environment.

Natural Selection

The process in which heritable traits that enhance survival and reproduction become more common in a population over generations.

Selective Pressure

An environmental factor that favors certain phenotypes and disfavors others, guiding evolution in a population.

Adaptation

A structural, behavioural, or physiological feature that increases an organism’s likelihood of surviving to reproduce.

Speciation

The formation of new species when populations become reproductively isolated from one another.

Adaptive Radiation

The rapid diversification of a single ancestral species into many species, each adapted to different environments.

Geographic Barrier

A physical feature (e.g., glacier, lava flow, island) that isolates populations and can lead to speciation.

Extinction

The complete disappearance of a species from Earth.

Mass Extinction

A relatively short period in which a large percentage of Earth’s species become extinct.

Mutagen

Any substance or event that increases the rate of mutation in DNA.

Physical Mutagen

A mutagen that physically alters DNA structure, such as X-rays or UV radiation.

Chemical Mutagen

A mutagen that chemically reacts with DNA, such as nitrites or industrial gas fumes.

Carcinogen

A substance or agent that causes cancer; many carcinogens are mutagens (e.g., cigarette smoke, UV radiation).

Artificial Selection

Human-directed breeding that applies selective pressure to develop or enhance desirable traits in organisms.

Selective Breeding

The intentional mating of individuals with preferred traits to produce offspring exhibiting those traits.

Monoculture

The agricultural practice of repeatedly planting the same crop variety over large areas, reducing genetic diversity.

Beneficial Mutation

A genetic change that provides an organism with an advantage under certain environmental conditions.

Harmful Mutation

A genetic change that damages cell function, causes disease, or leads to uncontrolled cell growth.

Abiotic Factor

A non-living environmental component (e.g., temperature, sunlight) that can act as a selective pressure.

Evolutionary Divergence

The accumulation of genetic differences between populations, leading to distinct evolutionary paths.

Galápagos Finches

A classic example of adaptive radiation where finch species evolved diverse beak shapes to exploit different food sources.