Question

As Wallace traveled the Malay Archipelago, he noticed that western islands had placental mammals, like monkeys. Eastern islands had marsupial mammals, like kangaroos. How did Wallace explain this distribution?

Answer 1

Answer:

The options

A. Marsupial and placental mammals live in different habitats. Monkeys could only survive in the western islands and kangaroos in the eastern islands.

B. Monkeys and tree kangaroos compete against one another and cannot live together.

C. God specially created monkeys on one set of islands and kangaroos on the other.

D. The western islands were once connected to Asia and the eastern islands had been connected to Australia. The islands had never been connected to eachother.

The CORRECT ANSWER IS D.

D. The western islands were once connected to Asia and the eastern islands had been connected to Australia. The islands had never been connected to eachother.

Explanation:

Several forms of animals were restricted to several regions as a result of species that originated from pre-existing, nearby species. Since, the western islands were once all connected, they would possess or show the same species, which are also observed in the mainland in Asia. The eastern islands happened to be once all connected and had the same species, which is located in Australia

Answer 2

Answer:

Through the movements of the continents.

Explanation:

Alfred Russel Wallace was a British scientist who researched evolution and natural selection around the same time as Darwin and some of his papers were published together with Darwin.

The given example in the question, why the western islands had mammals and the eastern islands did not was explained by Wallace as "because the islands were never connected by land before throughout the movements of the continents in the history of the world and therefore the species never had the chance to cross to other islands and evolved seperately."

I hope this answer helps.