Final answer:
Evolution can occur in two main patterns: gradualism, with a slow and steady pace, and punctuated equilibrium, with rapid bursts of change followed by long periods of stasis. The fossil record provides evidence supporting punctuated equilibrium, although both processes contribute to species evolution.
Step-by-step explanation:
Evolution may occur at a slow, steady rate, which is called gradualism, or there may be brief periods of rapid evolution, which is called punctuated equilibrium. The concept of gradualism suggests that evolutionary change occurs continuously at a slow pace. In contrast, the punctuated equilibrium model posits that evolution generally happens in quick spurts, particularly when a new species appears, followed by long periods with little to no evolutionary change. This idea is supported by the fossil record, which often shows long durations of stasis interrupted by sudden changes. Both theories highlight different aspects of the evolutionary process and the conditions that drive these changes. Gradual speciation is most likely in stable environments, while punctuated equilibrium can result from rapid environmental changes, both leading to the divergence of species.