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Gradualism suggests that change is gradual with the accumulation of unique morphological adaptation. Punctuated Equilibrium suggests that rapid change occurs, with a new species “erupting” from the ancestral lineage and then staying the same thereafter.
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Gradualismsuggests that change is gradual with the accumulation of unique morphological adaptation. • Punctuated Equilibriumsuggests that rapid change occurs, with a new species “erupting” from the ancestral lineage and then staying the same thereafter.
The evolution of new species by gradual accumulation of small genetic changes over long periods of time • Slow and steady change in an organism • Over a short period of time it is hard to notice Gradualism
Current living zebras (top), extinct quaggas (bottom) Gradualism
Stable periods of no change (genetic equilibrium) interrupted by rapid changes involving many different lines of descent • Rare, rapid events of branching speciation Punctuated Equilibrium
Horseshoe crabs have changed little since their first appearance in the fossil record. • They are in a state of equilibrium Punctuated Equilibrium
Similar to gradualism Similar to punctuated evolution