Key Concepts in Evolution and Species Diversity

Species richness

The number of different species in a given area.

Species evenness

The relative abundance of different species in a community.

Phylogeny

The evolutionary history and relationships among species.

Evolution

The change in genetic composition of a population over time.

Microevolution

Small genetic changes within a population over a short time.

Macroevolution

Large-scale evolutionary changes that result in new species.

Gene

A unit of heredity made of DNA that codes for a trait.

Genotype

The genetic makeup of an organism.

Phenotype

The observable traits of an organism.

Mutation

A random change in DNA that can lead to genetic variation.

Recombination

The reshuffling of genes during reproduction, increasing diversity.

Evolution by artificial selection

Human-driven breeding for desired traits.

Evolution by natural selection

Traits that improve survival and reproduction become more common.

Fitness

An organism's ability to survive and reproduce.

Adaptation

A trait that improves an organism's survival and reproduction.

Gene flow

Movement of genes between populations through migration.

Genetic drift

Random changes in gene frequencies, often in small populations.

Bottleneck effect

Genetic diversity loss due to a drastic population reduction.

Extinction

The complete disappearance of a species.

Founder effect

Genetic differences caused when a small group starts a new population.

Geographic isolation

Physical separation of populations, leading to speciation.

Allopatric speciation

New species form due to geographic isolation.

Reproductive isolation

Populations that can no longer interbreed and produce fertile offspring.

Sympatric speciation

New species evolve without geographic isolation.

Genetically modified organism (GMO)

An organism with altered DNA through genetic engineering.

Range of tolerance

The environmental conditions an organism can survive in.

Fundamental niche

The full range of conditions an organism could live in.

Realized niche

The actual conditions an organism lives in due to competition.

Distribution

The geographic area where a species is found.

Niche generalist

A species that can survive in a wide range of conditions.

Niche specialist

A species adapted to a narrow set of conditions.

Mass extinction

A rapid, widespread loss of many species at once.