( ( ( Microevolution -- ) ( variation ( within ( species 2 ) ) ) ) . )
(ROOT (NP (NP (NNP Microevolution)) (: --) (NP (NP (NN variation)) (PP (IN within) (NP (NN species) (CD 2)))) (. .)))
Microevolution--variation within species 2.
(ROOT (S (NP (NNP Microevolution)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NNS species)) (VP (VBZ changes) (PP (IN in) (NP (NP (JJ small) (NNS ways)) (PP (IN over) (NP (NN time))))))))) (. .)))
Microevolution is when a species changes in small ways over time.