Which of the following is left unexplained by the biological species concept?

• A. The classification of asexual organisms
• B. The importance of gene flow between populations
• C. The role of reproductive isolation in speciation
• D. The definition of species based on interbreeding

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the biological species concept. It defines a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable offspring with members of other groups.
2. Step 2: Analyze the limitations of the biological species concept. It relies heavily on the ability to interbreed and produce fertile offspring, which is not applicable to organisms that reproduce asexually.
3. Step 3: Consider the classification of asexual organisms. Since asexual organisms do not interbreed, the biological species concept does not provide a clear framework for defining species in these cases.
4. Step 4: Evaluate the other options provided in the question. The biological species concept does explain the importance of gene flow between populations and the role of reproductive isolation in speciation, as these are central to its definition.
5. Step 5: Conclude that the classification of asexual organisms is left unexplained by the biological species concept, as it does not account for species that do not reproduce sexually.