1. The Puzzle of Life’s Diversity 15.1

2. Evolution Change in a kind of organism over time.

3. Theory Well-tested explanation that unifies a broad range of observations.

4. Fossil Preserved remains or evidence of an ancient organism.

5. Key Concept What was Charles Darwin’s contribution to science? Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way life changes over time.

6. Key Concept What pattern did Darwin observe among organisms of the Galapagos Islands? Darwin observed that the characteristics of many animals and plants varied noticeably among the different islands of the Galapagos.