( There ( ( are ( ( two ( generally ( accepted varieties ) ) ) ( of ( evolution ( , ( ( microevolution and ) macroevolution ) ) ) ) ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD two) (RB generally) (VBN accepted) (NNS varieties)) (PP (IN of) (NP (NN evolution) (, ,) (NN microevolution) (CC and) (NN macroevolution))))) (. .)))
There are two generally accepted varieties of evolution, microevolution and macroevolution.
(ROOT (S (NP (NNP Macroevolution)) (VP (VBZ happens) (SBAR (WHADVP (WRB when)) (S (NP (NP (NNS forces)) (PP (IN of) (NP (NN evolution)))) (VP (VBP work) (PP (IN over) (NP (NP (DT a) (JJ long) (NN period)) (PP (IN of) (NP (NN time))))))))) (. .)))