microevolution

mi·cro·evo·lu·tion

noun
\ˈmī-krō-ˌev-ə-ˈlü-shən also -ˌē-və-\

Definition of MICROEVOLUTION

: comparatively minor evolutionary change involving the accumulation of variations in populations usually below the species level

—mi·cro·evo·lu·tion·ary \-shə-ˌner-ē\ adjective