Question

this type of evolution occurs very slowly over very long periods of time. population gradualism punctuated equilibrium species

Explanation:

Gradualism is the evolutionary model defined by slow, continuous changes in species over extended geological timeframes, matching the description provided. The other options do not fit: population and species are biological units, not evolutionary rate models; punctuated equilibrium describes long periods of stasis interrupted by rapid evolutionary change.

Answer:

Gradualism