Unit 7

Natural Selection

The process by which organisms with favorable traits are more likely to survive and reproduce, passing their traits to the next generation.

Artificial Selection

The intentional breeding of organisms with desirable traits by humans to produce specific characteristics in future generations.

Disruptive Selection

Selection that favors extreme phenotypes over intermediate phenotypes.

Stabilizing Selection

Selection that favors intermediate phenotypes over extreme phenotypes.

Directional Selection

Selection that favors one extreme phenotype, leading to a shift in allele frequency.

Five factors of Evolution according to Hardy- Weinberg

The five conditions that must be met for a population to be in Hardy-Weinberg equilibrium: large population size, random mating, no mutations, no gene flow, and no natural selection.

Genetic Drift

Random changes in allele frequencies in a population, which can lead to reduced genetic variation.

Founder’s Effect

A phenomenon that occurs when a small group from a population starts a new population, leading to limited genetic diversity.

Bottleneck Effect

A reduction in genetic diversity due to a significant reduction in population size, often caused by environmental events.

Hardy-Weinberg Equilibrium

A principle that states allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary influences.

Homologous Structures

Anatomical features in different species that are similar due to shared ancestry.

Analogous Structures

Structures in different species that have similar functions but evolved independently, not from a common ancestor.

Prezygotic Isolation

Reproductive barriers that occur before fertilization, preventing mating or fertilization between species.

Postzygotic Isolation

Reproductive barriers that occur after fertilization, affecting hybrid viability or fertility.

Biological Species Concept

The definition of a species as a group of organisms that can interbreed and produce fertile, viable offspring.

Allopatric Speciation

The formation of new species when populations are geographically isolated from each other.

Sympatric Speciation

The formation of new species from a surviving ancestral species while both continue to inhabit the same geographic region.