Chapter 20, Problem 44A

Summary Introduction

To indicate:

The kind of data or evidence one would expect to find in the two organisms that have begun to evolve into separate species according to molecular clock technique

Introduction:

A molecular clock is a model that is used by systematics to compare DNA sequences from two different species to estimate how long the species have been evolving since they diverged from a common ancestor. Biologists use molecular clocks to compare DNA sequences or amino acid sequences of genes that are shared by different species.

Answer to Problem 44A

If the two organisms have begun to evolve into separate species according to molecular clock technique, the DNA sequences or amino acid sequences of genes that are shared by these two species would provide evidence of presence of ancestral genes. The differences between the genes indicate the presence of mutations. The more mutations that have accumulated, the more time has passed since divergence.

Explanation of Solution

Molecular clock technique gives us information about mutations that have accumulated over time in organisms. By comparing the DNA sequences or amino acid sequences of genes we can come to know how much time has elapsed since divergence of the two species. Data about neutral mutations will help to determine the degree of relationship between the two species.