( Gradualism ( ( is ( ( the key ) ( to Darwinism ) ) ) . ) )
(ROOT (S (NP (NNP Gradualism)) (VP (VBZ is) (NP (NP (DT the) (NN key)) (PP (TO to) (NP (NNP Darwinism))))) (. .)))
Gradualism is the key to Darwinism.
(ROOT (S (NP (NNP Darwin)) (VP (VBD believed) (PP (IN in) (NP (NN gradualism)))) (. .)))