Chapter 11, Problem 1LTB

What observations did Darwin make on the Galapagos Islands that helped convince him that evolution occurs?

1. the existence of animals that did not fit into Linnaeus’s classification system;
2. the similarities and differences among cacti and tortoises on the different islands;
3. the presence of species he had seen on other tropical islands far from the Galapagos;
4. the radioactive age of the rocks of the islands;
5. fossils of human ancestors

Summary Introduction

Introduction:

Evolution is a process in which the changes that occur in an organism. In the Galapagos Islands, Darwin found the pattern of differences between the closely allied forms in different islands and between the mainland and island.

Answer to Problem 1LTB

Solution:

The correct answer is option (b) the similarities and differences among cacti and tortoises in different islands.

Explanation of Solution

Explanation/justification for the correct answer:

Option (b) the similarities and differences among cacti and tortoises in islands. In the Galapagos Islands, Darwin found similarities and differences in different varieties of organisms and that some varieties were unique to certain islands. Darwin also found various types of cacti and tortoises in these islands and then, concluded that the different varieties must have evolved from a single ancestor. Thus, the similarities and differences in varieties of cacti and tortoises helped him to conclude that evolution occurs. So, the correct answer is option (b).

Explanation for incorrect answer:

Option (a) the existence of animals that did not fit into Linnaeus’s classification system. The Linnaeus’s classification system is a system to classify and name organisms and does not discuss evolution. So, this is an incorrect option.

Option (c) the presence of species he had seen in other tropical islands apart from the Galapagos. Environmental conditions play an important role in evolution so, the species he had seen on other tropical islands did not contribute towards his findings about evolution. So, this is an incorrect answer.

Option (d) the radioactive age of the rocks of the islands. Darwin’s conclusions were not based upon radioactive studies. So, this is an incorrect answer.

Option (e) fossils of human ancestors. The conclusions that Darwin made were through observation of characteristics in cacti and tortoises. So, this is an incorrect answer.

Conclusion

The similarities and differences between varieties of cacti and tortoises helped Darwin to conclude that evolution occurs. Hence, the correct answer is option (b) the similarities and differences between cacti and tortoises in different islands.