1. Darwin’s Observations Notes
7d. Variation within a species increases the likelihood that at least some members of a species will survive under changed environmental conditions.

2. Objectives
Describe how Darwin arrived at his idea about species variation.
Recognize how Darwin’s discoveries supported Lyell’s ancient-Earth theory.

3. Vocabulary
Variation
Adaptation

4. Darwin observed differences among island species.

5. Darwin spent more than 20 years compiling evidence before publishing in 1859 his ideas on how evolution works.

6. Variation
Difference in the physical traits of an individual from those of other individuals in the group to which it belongs.

7. Adaptation
Inherited trait that is selected for over time because it allows organisms to better survive in their environment.

8. Adaptations Within Species – Galapagos tortoises (Geochelone elephantopus) are evidence that species can adapt to their environment:
Domed tortoises have short necks and legs, and live in areas with low vegetation.
Saddle-backed tortoises have a high shell edge, allowing them to stretch their long necks.

9. Darwin observed fossil and geologic evidence supporting an ancient Earth.