( ( On ( ( the origin ) ( of ( species ( by ( sympatric speciation ) ) ) ) ) ) . )
(ROOT (FRAG (PP (IN On) (NP (NP (DT the) (NN origin)) (PP (IN of) (NP (NP (NNS species)) (PP (IN by) (NP (JJ sympatric) (NN speciation))))))) (. .)))
On the origin of species by sympatric speciation.
(ROOT (S (NP (JJ Sympatric) (NN speciation)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (JJ new) (NN species)) (VP (VBZ arises) (PP (IN without) (NP (JJ geographic) (NN separation))))))) (. .)))