We have the following problem:
On the Galapagos Islands, several species of iguanas live on land, and some species live only in marine environments. It is possible that both of these species diverged from a common ancestor. Both species lay their eggs in the sand.
The marine iguanas are sustained on a diet of algae in the water, while land iguanas generally eat cactus plants on the islands. And while algae are abundant in the water, cacti are much rarer on land.
Explain how these two species could have developed from a single common ancestor. What do you think could have caused this to happen?
During the course of history, rats and goats have been introduced to the island as nonnative species. The rats usually eat iguana eggs, while goats like to eat the cactus plants found on the island.
How might the introduction of rats and goats have affected both iguana species?
The answers to this question will be found in the comments to this post.