Chapter 19.2 (Pgs. 546-551):Patterns and Processes of Evolution

Microevolution*- Is evolution that happens on a small

scale

- Includes natural selection and genetic drift

- Can involve the speciation of a few species from a common ancestor

Macroevolution- Is large changes in anatomy and

behavior over long periods of time

- Is the evolution of many new species from an ancient ancestor

Extinction- Occurs when an organism is no

longer fit for its environment

- Background extinction is a normal extinction rate of species

- Mass extinction is the extinction of a large number of species at one time

- Usually due to a natural disaster or rapidly changing climate conditions

Rate of Evolution

- Can change for different organisms at different periods in time

- Gradualism- Slow, steady changes accumulate

over time

- Punctuated Equilibrium- Long periods of very slow change

are punctuated by periods of rapid change

Adaptive Radiation

- A single or a few species rapidly evolves into many new species

- Can occur when a species migrates into a new area

- Can occur after extinction, and new habitats have become available