Which of the following statements about adaptive radiation is correct?

• A. Adaptive radiation refers to the gradual accumulation of small genetic changes within a single population over time.
• B. Adaptive radiation results in decreased biodiversity within an ecosystem.
• C. Adaptive radiation occurs when a single ancestral species rapidly diversifies into multiple new species, each adapted to a different ecological niche.
• D. Adaptive radiation only occurs in response to mass extinction events.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of adaptive radiation. Adaptive radiation is an evolutionary process where a single ancestral species rapidly diversifies into multiple new species, each adapted to a specific ecological niche. This often occurs when new habitats or resources become available, or after mass extinction events create ecological opportunities.
2. Step 2: Analyze the first statement: 'Adaptive radiation refers to the gradual accumulation of small genetic changes within a single population over time.' This describes microevolution, not adaptive radiation. Adaptive radiation involves the rapid formation of multiple species, not gradual changes within a single population.
3. Step 3: Analyze the second statement: 'Adaptive radiation results in decreased biodiversity within an ecosystem.' This is incorrect because adaptive radiation typically increases biodiversity by creating multiple new species adapted to different niches.
4. Step 4: Analyze the third statement: 'Adaptive radiation occurs when a single ancestral species rapidly diversifies into multiple new species, each adapted to a different ecological niche.' This is correct and aligns with the definition of adaptive radiation.
5. Step 5: Analyze the fourth statement: 'Adaptive radiation only occurs in response to mass extinction events.' This is incorrect because while mass extinction events can trigger adaptive radiation, it can also occur in other scenarios, such as when species colonize new environments with unoccupied niches (e.g., Darwin's finches on the Galápagos Islands).