Natural selection

Directional selection

A process that can cause a shift in traits due to environmental changes, favoring traits that enhance survival, thus decreasing variation.

Disruptive selection

A form of selection where extreme phenotypes are favored over intermediate phenotypes, potentially leading to the formation of new species.

Stabilizing selection

A type of selection that favors average phenotypes by removing extreme variation, which can threaten the adaptability of a species.

Anagesis

The accumulation of changes in one species that leads to the development of another species.

Cladogenesis

The process of branching evolution where one or more new species arise from an ancestral species while the ancestral species continues to exist.

Genetic Drift

A random process that can result in the loss of alleles in a population, significantly affecting small populations.

Bottleneck effect

A drastic reduction in population size due to an event that filters organisms randomly, often caused by natural disasters.

Founder effect

The loss of genetic variation when a new population is established by a small number of individuals from a larger population.

Postzygotic isolation

A reproductive barrier that occurs after fertilization, preventing hybrid offspring from developing or breeding successfully.

Developmental isolation

A form of postzygotic isolation where fertilization occurs but embryonic development is irregular and leads to abortion.

Hybrid inability

A scenario where hybrids can develop and be born but do not reach reproductive age.

Hybrid sterility

A situation where hybrids survive to adulthood but are sterile and unable to reproduce.

Hybrid elimination

Selective elimination of hybrids, occurring in sympatric speciation where hybridization is possible but leads to reduced fitness of hybrid offspring.