their natural instinct for self-preservation 
(ROOT (NP (NP (PRP$ their) (JJ natural) (NN instinct)) (PP (IN for) (NP (NN self) (HYPH -) (NN preservation)))))
(ROOT (NP (NP (PRP$ ) (JJ ) (NN )) (PP (IN ) (NP (NN ) (HYPH ) (NN )))))