( ( ( ( Evolution ( of ( Animal Behavior ) ) ) ( To ( the extent ) ) ) ( that ( behaviors ( are ( controlled ( by genes ) ) ) ) ) ) ( , ( they ( ( may ( evolve ( through ( natural selection ) ) ) ) . ) ) ) )
(ROOT (S (S (VP (VBN Evolution) (PP (IN of) (NP (NNP Animal) (NNP Behavior))) (PP (TO To) (NP (DT the) (NN extent))) (SBAR (IN that) (S (NP (NNS behaviors)) (VP (VBP are) (VP (VBN controlled) (PP (IN by) (NP (NNS genes))))))))) (, ,) (NP (PRP they)) (VP (MD may) (VP (VB evolve) (PP (IN through) (NP (JJ natural) (NN selection))))) (. .)))
Evolution of Animal Behavior   To the extent that behaviors are controlled by genes, they may evolve through natural selection.
(ROOT (S (NP (NNP Animal) (NNS behaviors)) (VP (VBP are) (VP (VBN controlled) (PP (IN by) (NP (NP (DT both) (NNS genes) (CC and) (NNS experiences)) (PP (IN in) (NP (DT a) (VBN given) (NN envionment))))))) (. .)))