( natural ( ( selection ( ( ( ( the process ) ( of ( survival ( of ( ( ( the fittest ) , ) ( ( by which ) ( ( organisms ( that ( adapt ( to ( their environment ) ) ) ) ) survive ) ) ) ) ) ) ) and ) ( those ( that ( ( do n't ) disappear ) ) ) ) ) . ) )
(ROOT (SINV (ADJP (JJ natural)) (VP (VBZ selection)) (NP (NP (NP (DT the) (NN process)) (PP (IN of) (NP (NP (NN survival)) (PP (IN of) (NP (NP (DT the) (JJS fittest)) (, ,) (SBAR (WHPP (IN by) (WHNP (WDT which))) (S (NP (NP (NNS organisms)) (SBAR (WHNP (WDT that)) (S (VP (VBP adapt) (PP (TO to) (NP (PRP$ their) (NN environment))))))) (VP (VBP survive))))))))) (CC and) (NP (NP (DT those)) (SBAR (WHNP (WDT that)) (S (VP (VBP do) (RB n't) (VP (VB disappear))))))) (. .)))
natural selection the process of survival of the fittest, by which organisms that adapt to their environment survive and those that don't disappear.
(ROOT (S (NP (JJ Natural) (NN selection)) (VP (VBZ is) (NP (NP (DT the) (NN process)) (SBAR (WHNP (WDT that)) (S (VP (VBZ allows) (NP (NNS organisms)) (PP (IN with) (NP (JJR better) (NNS traits) (S (VP (TO to) (VP (VB survive) (CC and) (VB produce))))))))))) (. .)))