Final answer:
Punctuated equilibrium usually occurs in small populations that experience rapid environmental change, leading to bursts of rapid evolution. This contrasts with gradual speciation, which happens in stable environments and results in a steady divergence of species over longer periods.
Step-by-step explanation:
Punctuated equilibrium is a concept in evolutionary biology that posits that species experience periods of little or no evolutionary change punctuated by brief periods of rapid evolution. This model is in contrast to gradualism, which suggests a slow and steady evolutionary change over time.
Conversely, gradual speciation is more likely to occur in large populations residing in stable conditions over long periods. In both models, speciation results in the divergence and evolution of new species, which can be observed in the fossil record as bursts of change following long stases. Only about 30 to 35 percent of speciation events show evidence of punctuated change, while the remainder suggests a pattern of gradualism.