Which of the following best describes the purpose of a phylogenetic tree in taxonomy?

• A. To classify organisms based solely on physical similarities
• B. To illustrate the evolutionary relationships among different species
• C. To show the geographic distribution of species
• D. To organize organisms by their ecological roles

Answer: (B)

Verified step by step guidance

1. Understand the purpose of a phylogenetic tree: A phylogenetic tree is a diagram that represents evolutionary relationships among organisms. It is based on shared common ancestry and genetic, morphological, or molecular data.
2. Eliminate incorrect options: The option 'To classify organisms based solely on physical similarities' is incorrect because phylogenetic trees use more than just physical traits; they incorporate genetic and evolutionary data.
3. Evaluate the option 'To show the geographic distribution of species': This is not the primary purpose of a phylogenetic tree. Geographic distribution may be related but is not the focus of the tree.
4. Consider the option 'To organize organisms by their ecological roles': This is also incorrect because ecological roles are not the basis for constructing phylogenetic trees.
5. Select the correct answer: The correct purpose of a phylogenetic tree is 'To illustrate the evolutionary relationships among different species,' as it shows how species are related through common ancestors and evolutionary history.