Chapter 15, Problem 1A

Solution

To determine:

To replace the underlined word in a sentence to make it correct.

Introduction:

Evolution can be defined as the unrolling of nature that brings about an orderly change from one form to another which results in the descendants to become different from the ancestors.

Evolutionary biology is history of development of newer forms of life from the pre-existing ones in various periods of the time on earth.

The word which can be filled to replace species changes over time is Evolution. So the correct sentence is Natural selection is a mechanism for Evolution.

The theory of natural selection was given by Charles Darwin and Alfred Wallace in 1858 and this theory is also known as Darwin-Wallace theory.

Natural selection is differential reproduction which means some members of population have genes that enable them to grow up and reproduce at higher rate and leave more surviving offspring in the next generation than others. It will result the gene to become predominant in the gene pool as it is producing more offspring that continue for many generations. Natural selection can result in organisms that are more likely to survive and reproduce and eventually leads to speciation and hence evolution.

The theory of natural selection was based on the following prepositions:

• Struggle for existence
• Variation and heredity
• Survival of the fittest