What term describes a series of predictable and orderly changes within an ecosystem over time?

• A. Succession
• B. Evolution
• C. Mutation
• D. Adaptation

Answer: (A)

Succession describes a predictable sequence of changes in which the species composition of an ecosystem changes over time after a disturbance or when a new habitat becomes available. It starts with pioneer species that colonize bare or disturbed areas, followed by intermediate communities, and often progresses toward a more stable climax community (though many ecosystems remain dynamic). This idea captures why the ecosystem’s structure and function change in a orderly, time-based way.

Evolution, mutation, and adaptation operate at the level of organisms and populations: evolution is changes in allele frequencies over generations, mutation is DNA changes, and adaptation is a trait that improves fitness. They explain genetic or trait changes, not the stepwise reassembly of the whole community over time.