Question

Which of the following observations helped Darwin shape his concept of descent with modification?

(A) Species diversity declines farther from the equator.

(B) Fewer species live on islands than on the nearest continents.

(C) Birds live on islands located farther from the mainland than the birds' maximum nonstop flight distance.

(D) South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

Short answer

1. The statement "Species diversity declines farther from the equator" is false.
2. The statement "Fewer species live on islands than on the nearest continents" is false.
3. The statement "Birds live on islands located farther from the mainland than the birds' maximum nonstop flight distance" is false.
4. The statement "South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe" is true.

Step-by-step solution

Darwin, evolution and natural selection

Natural selection and evolution are interlinked phenomena. Darwin studied evolution and formed several ideas regarding evolutionary trends. He challenged the common misconception that adaptive traits cannot pass on to successive generations and successfully proved his hypothesis.

He observed this trend in all the living organisms and called the phenomenon descent with modification. Darwin also figured out that the occurrence of a trait was hugely dependent on its natural selection.

Explanation for option (A)

The genetic variations must be inherited among individuals to produce a viable impact on the population. The diversity of species does not decrease farther from the equator. Instead, it increases while moving farther from the equator.

Thus, the species diversity increases while moving farther from the equator.

Therefore, the given statement is false.

Explanation for option (B)

Species reside on the islands more diversely compared to the nearest continents. The species' population on the islands was not the observation that led Darwin to shape the concept of descent with modification.

Thus, the species diversity among islands and continents did not lead Darwin to form the concept.

Therefore, the given statement is false.

Explanation for option (C)

Birds are present on the islands that are not very far from the mainland. Birds need to migrate, and hence the islands should not be far away from their maximum nonstop flight distance.

Thus, the birds that dwell on islands are not located farther from the mainland.

Therefore, the given statement is false.

Explanation for option (D)

The South American temperate plants possess more similarities to the tropical plants of South America than the temperate plants of Europe. According to Darwin, the favorable traits first get adapted by the population.

These adaptive traits got incorporated into the population and passed on to the upcoming generations.

As the South American plants are genetically similar, the plants are adapted to different environments, temperate and tropical. Both types of plants show descent with modification.

Thus, the temperate and tropical plants from South America had more genetic similarities.

Therefore, the given statement is true.