Question

4
on the galapagos islands, darwin observed tortoises with domed and saddle-shaped shells. how did darwins observations of these tortoises help him form the theory of evolution by natural selection?
a. the tortoises helped to confirm that two similar species do not necessarily share a common ancestor.
b. the tortoises provided evidence that the galapagos had been colonized by tortoises multiple independent times.
c. the tortoises helped to confirm that environmental changes cannot affect the characteristics of a species.
d. the tortoises provided evidence that different species have adaptations suited to their particular environments.

Explanation:

Darwin observed that Galápagos tortoises with domed shells lived in areas with low, easy-to-reach vegetation, while those with saddle-shaped shells lived in areas with taller cacti (their shells allowed them to stretch their necks to reach the cacti). This showed that the tortoises' physical traits were adaptations to their specific environments, which supported the idea that natural selection favors traits that help organisms survive and reproduce in their habitats. Options A, B, and C are incorrect: Darwin's work supported common ancestry, the tortoises likely shared a single ancestor that colonized the islands, and his observations showed environmental factors do shape species characteristics.

Answer:

D. The tortoises provided evidence that different species have adaptations suited to their particular environments.