( ( A trait ) ( ( ( is ( an adaptation ) ) ( if ( it ( was ( shaped ( by ( natural selection ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN trait)) (VP (VBZ is) (NP (DT an) (NN adaptation)) (SBAR (IN if) (S (NP (PRP it)) (VP (VBD was) (VP (VBN shaped) (PP (IN by) (NP (JJ natural) (NN selection)))))))) (. .)))
A trait is an adaptation if it was shaped by natural selection.
(ROOT (S (NP (NNP Evolution)) (VP (VBZ occurs) (PP (IN by) (NP (NP (JJ natural) (NN selection)) (, ,) (NP (NP (DT a) (NN process)) (SBAR (WHADVP (WRB whereby)) (S (NP (JJ better-adapted) (NNS members)) (VP (VBP pass) (PRT (RP along)) (NP (PRP$ their) (NNS traits)) (, ,) (PP (VBG according) (PP (TO to) (NP (NN darwin))))))))))) (. .)))