How is a species defined according to the biological species concept?

• A. A group of organisms that share similar physical characteristics.
• B. A group of organisms that can interbreed and produce fertile offspring in nature.
• C. A group of organisms that occupy the same ecological niche.
• D. A group of organisms with identical genetic sequences.

Answer: (B)

Verified step by step guidance

1. Understand the biological species concept: It defines a species as a group of organisms that can interbreed and produce fertile offspring in natural conditions.
2. Clarify why physical characteristics alone are insufficient: Similar physical traits do not guarantee reproductive compatibility or fertile offspring.
3. Explain the importance of reproductive isolation: Species are distinct when they are reproductively isolated from other groups, meaning they cannot successfully interbreed with members of other species.
4. Discuss why ecological niche or genetic similarity is not the sole criterion: Organisms occupying the same niche or having similar genetic sequences may still belong to different species if they cannot interbreed.
5. Conclude by emphasizing the key criterion: The ability to interbreed and produce fertile offspring is the defining feature of a species under the biological species concept.