Darwin and Evolution of Populations

Evolution

The gradual change of a species over time to better suit their environment.

Natural Selection

A process in which individuals with favorable inherited traits are more likely to survive and reproduce.

Adaptation

An inherited trait that makes an organism more fit for its environment.

Fitness

An organism's ability to survive and reproduce.

Niche

The role or function of an organism or species in an ecosystem.

On the Origin of Species

Darwin's 1859 book that introduced the scientific theory of evolution through natural selection.

Genetic Drift

Changes in allele frequencies in a population due to random chance, not natural selection.

Founder Effect

Occurs when a few individuals become isolated from a larger population and start a new population, leading to different allele frequencies.

Bottleneck Effect

A drastic reduction in population size due to environmental change, causing loss of genetic variation.

Gene Flow

The movement of alleles into or out of populations through immigration or emigration.

Sexual Selection

When certain adaptations increase an individual's ability to secure a mate, leading to evolutionary changes.

Directional Selection

Occurs when conditions favor individuals at one end of the phenotypic range.

Disruptive Selection

Occurs when conditions favor individuals at both extremes of the phenotypic range.

Stabilizing Selection

Occurs when conditions favor intermediate variants and act against extreme phenotypes.

Heterozygote Advantage

Occurs when heterozygotes have higher fitness than both homozygotes, maintaining multiple alleles at a locus.

Microevolution

The change in allele frequencies in a population over many generations.

Artificial Selection

The process by which humans modify other species by selecting and breeding individuals with desired traits.

Descent with Modification

Darwin's phrase summarizing the perception that all organisms are related through descent from a common ancestor.

Fossils

Preserved remains or traces of organisms from the past, providing evidence for evolution.

Adaptation Examples

Traits like large beaks in finches that allow them to crack open seeds.

Allele Frequency

The relative frequency of an allele at a genetic locus in a population.