mi·cro·ev·o·lu·tion 
(mī′krō-ĕv′ə-lshən, -ē′və-)
(mī′krō-ĕv′ə-lshən, -ē′və-)n.
Small-scale evolution consisting of genetic changes occurring usually within a single species and over a shorter period of time than in macroevolution.
mi′cro·ev′o·lution·ar′y adj.