Chapter 9, Lesson 3

Rate of Change

Chapter 9, Lesson 3

Pages 350-353

• 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

Fill in the Blanks

The _________ _________ has given scientists information about past life on Earth.

Multiple Choice

A new species can form when a group of individuals remains completely separated from the rest of its family long enough to evolve different traits that prevent reproduction.

• true

• false

Multiple Choice

A natural catastrophe such as a river or volcano may separate group members

• true

• false

Multiple Choice

The Kaibab squirrel and the Abert's squirrel are members of the same species.

• true

• false

Multiple Choice

Evolution explains how variations can lead to changes in a species.

• true

• false

Multiple Choice

__________ occurs when some members of a species become cut off.

• gradualism

• isolation

• mate or reproduce

• punctuated equilibrium

Multiple Choice

The cow and the dog are separate species, unable to _________ with each other.

• gradualism

• isolation

• mate or reproduce

• punctuated equilibrium

Multiple Choice

__________ is a pattern of new species forming over very long periods of time.

• gradualism

• isolation

• mate or reproduce

• punctuated equilibrium

Multiple Choice

__________ is a pattern of new species evolving during short periods of rapid change.

• gradualism

• isolation

• mate or reproduce

• punctuated equilibrium