1. KEY CONCEPT Darwin’s voyage provided insight on evolution.

2. Darwin observed differences among Galapagos island species.
Variation is a difference in a physical trait.
Domed tortoises have a short neck and short legs and live in areas with low vegetation.
Saddle-backed tortoises have a high shell edge allowing them to stretch their long necks to reach taller vegetation.

3. Finches on certain Galapagos Islands live in different environments and have beaks of different sizes and shapes. A. B.
A. Large cactus finch (Geospiza conirostris): Species in the genus Geospiza have thick beaks and can feed on large, hard seeds that require strength for crushing.
B. Small tree finch (Camarhynchus parvulus): Species in the genus Camarhynchus have biting strength at the tips of their beaks, which is useful for tearing vegetation.

4. An adaptations is a feature that allow an organism to better survive in its environment.
Species are able to adapt to their environment.
Adaptations can lead to genetic change in a population.

5. Darwin observed a) fossil and b) geologic evidence supporting an ancient Earth.
Darwin found fossils of extinct animals that resemble modern animals.
Darwin found fossil shells high up in the Andes mountains.

6. Darwin extended his observations to the evolution of organisms.
He saw land move from underwater to above sea level due to an earthquake.
Darwin extended his observations to the evolution of organisms.
Fig. This trilobite, an early marine invertebrate that is now extinct, was found in a loose rock bed in Ohio.