punctuatedequilibriumDynamik

Punctuated equilibrium is a theory in evolutionary biology that proposes a distinction between the tempo and the mode of evolution. It suggests that species experience long periods of relative morphological stability (stasis) interrupted by brief, rapid episodes of evolutionary change during speciation. The term was introduced in 1972 by Stephen Jay Gould and Niles Eldredge in response to patterns observed in the fossil record, where new forms often appear abruptly rather than as gradual transformations over long intervals.

In this view, the most significant evolutionary changes are concentrated in speciation events, often occurring in small, geographically isolated populations. During these periods, genetic drift, selection, and other processes can result in rapid phenotypic shifts, producing new species over relatively short geological times. Once formed, these new species may persist, showing little net change for long durations.

The theory emphasizes that it is a pattern or tempo of evolution as observed in the fossil record, not a claim that microevolution ceases. It does not deny gradual change within lineages but argues that long-term macroscopic changes are commonly tied to speciation events. Reception has been mixed; some paleontologists cite fossil sequences showing abrupt appearances and stasis, while others argue the record is biased or that gradual changes can occur too. Punctuated equilibrium has influenced discussions on macroevolution, stasis, and the relationship between short-term processes and long-term patterns.