Which of the following best describes our current understanding of how species evolve over time?

• A. Species remain unchanged unless a catastrophic event forces them to evolve suddenly.
• B. Species evolve only when individuals intentionally adapt to new environments during their lifetimes.
• C. Species evolve through the gradual accumulation of genetic changes that increase their fitness in a given environment.
• D. Species evolve because all individuals in a population acquire the same beneficial mutations simultaneously.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of evolution. Evolution refers to the process by which populations of organisms change over generations through variations in their genetic material. These changes can lead to adaptations that improve survival and reproduction in specific environments.
2. Step 2: Analyze the first option: 'Species remain unchanged unless a catastrophic event forces them to evolve suddenly.' This describes a concept called punctuated equilibrium, which is not the sole mechanism of evolution. Evolution can occur gradually without catastrophic events.
3. Step 3: Analyze the second option: 'Species evolve only when individuals intentionally adapt to new environments during their lifetimes.' This is incorrect because evolution does not involve intentional changes during an individual's lifetime. Traits acquired during a lifetime are not passed to offspring (Lamarckian inheritance is outdated).
4. Step 4: Analyze the third option: 'Species evolve through the gradual accumulation of genetic changes that increase their fitness in a given environment.' This aligns with the modern understanding of evolution through natural selection, where beneficial genetic mutations accumulate over time, improving fitness.
5. Step 5: Analyze the fourth option: 'Species evolve because all individuals in a population acquire the same beneficial mutations simultaneously.' This is incorrect because mutations occur randomly and independently in individuals, and beneficial mutations spread through populations over generations via natural selection.