• How do new species form?

• What patterns describe the rate of evolution?​

How do new species form?

• A new ​species can form when a group of individuals remains isolated from the rest of its species long enough to evolve different traits that prevent reproduction

• Species can be cut off or isolated from other members of the species by natural barriers such as a river or the Grand Canyon

• It is possible that species can become so different that they will no longer be able to mate and will become separate species​

Patterns that Describe Rate of Evolution

• Scientists have developed two patterns to describe the pace of evolution - gradualism and punctuated equilibrium

• Gradualism - pattern of evolution characterized by the slow and steady accumulation of small genetic changes over long periods of time

  • The fossil record contains examples of species as they go through these gradual changes

• Punctuated Equilibrium - pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change