( ( As ( physiological ( or ( environmental ( conditions change ) ) ) ) ) ( , ( ( ( an ( animal 's ) ) ( food ( and ( water requirements ) ) ) ) ( ( will change ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (NN physiological) (CC or) (JJ environmental) (NNS conditions) (NN change))) (, ,) (NP (NP (DT an) (NN animal) (POS 's)) (NN food) (CC and) (NN water) (NNS requirements)) (VP (MD will) (VP (VB change))) (. .)))
As physiological or environmental conditions change, an animal's food and water requirements will change.
(ROOT (S (NP (NP (DT A) (NN change)) (PP (IN of) (NP (NP (NN season)) (CC and) (NP (JJR less) (NN food))))) (ADVP (RB usually)) (VP (VB cause) (S (NP (JJ certain) (NNS animals)) (VP (TO to) (VP (VB migrate))))) (. .)))
A change of season and less food usually cause certain animals to migrate.