( ( ( The unit ) ( of evolution ) ) ( ( is ( the population ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN unit)) (PP (IN of) (NP (NN evolution)))) (VP (VBZ is) (NP (DT the) (NN population))) (. .)))
The unit of evolution is the population.
(ROOT (S (NP (NNP Population)) (VP (VBZ is) (NP (NP (DT the) (NN unit)) (PP (IN of) (NP (NN evolution))))) (. .)))