Natural Selection (short version)

Evolution

Change in the genetic makeup of a population over generations

Population

A group of organisms of the same species in one area

Allelic frequency

The proportion of a specific allele in a population

Gene pool

All the alleles in a population

Fitness

How well an organism survives and reproduces

Overproduction

More offspring are produced than the environment can support

Variation

Differences within a population

Artificial selection

Humans choose which traits get passed on

Natural selection

Individuals with helpful traits survive and reproduce more

Descent with modification

Over many generations, populations change

Directional selection

Favors one extreme phenotype

Stabilizing selection

Favors the average phenotype

Disruptive selection

Favors both extreme phenotypes

Speciation

Formation of new species

Reproductive isolation

Populations can no longer mate and produce fertile offspring

Phylogenetic tree

A diagram showing evolutionary relationships

Independent assortment

Alleles for different genes separate independently during meiosis

Linked genes

Genes on the same chromosome that tend to be inherited togethe