Convergent

Evolution towards similar characteristic

• Analogous structures

• Similar functions

  • wings

  • aquatic mammals versus fish

Divergent

Closely related species that evoled in different directions

• Homologous structures (different function but similar ancestor)

• Speciation due to environmental adaptations

Coevolution

Two species evolve in response to changes in each other

• Evolutionary arms race

  • adaptations to prevent predation lead to adaptations of predators in response to prey adaptations

Trait Changes

Traits and allele frequencies can change over time in different ways

• Directional

  • the environment favors one trait over another

• Stabilizing

  • the environment finds a middle ground between two traits

• Disruptive

  • the environment favor two extreme variations of a trait