9th Grade Biology SOL Practice Test

The pattern of evolutionary change: whether it happens in steady, gradual steps or in short bursts. The best description here says evolution occurs in rapid spurts separated by long periods of little or no change. This idea, called punctuated equilibrium, means species mostly stay the same for long times (stasis) and new forms arise quickly when conditions change or isolation occurs, producing noticeable change in a relatively short era. By contrast, gradualism envisions slow, continuous change over long periods; uniformitarianism is a geological principle about slow, ongoing processes shaping Earth over time; catastrophism focuses on sudden, dramatic events causing rapid changes but not the recurring pattern of long stability with brief rapid shifts. So the rapid-change-with-long-stasis pattern fits punctuated equilibrium.