( ( Individuals ( of ( different species ) ) ) ( ( may ( ( ( ( ( ( mate and ) even ) ( produce ( hybrid offspring ) ) ) , ) but ) ( without ( ( ( resulting ( gene flow ) ) ( -LRB- ( ( exchange ( of ( genetic ( materia l ) ) ) ) -RRB- ) ) ) ( between ( the ( two species ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Individuals)) (PP (IN of) (NP (JJ different) (NNS species)))) (VP (MD may) (VP (VP (VB mate)) (CC and) (ADVP (RB even)) (VP (VB produce) (NP (JJ hybrid) (NN offspring))) (, ,) (CC but) (VP (PP (IN without) (NP (NP (NP (JJ resulting) (NN gene) (NN flow)) (PRN (-LRB- -LRB-) (NP (NP (NN exchange)) (PP (IN of) (NP (JJ genetic) (NN materia) (NNS l)))) (-RRB- -RRB-))) (PP (IN between) (NP (DT the) (CD two) (NNS species)))))))) (. .)))
Individuals of different species may mate and even produce hybrid offspring, but without resulting gene flow (exchange of genetic materia l) between the two species.
(ROOT (S (SBAR (IN If) (S (NP (CD two) (NNS populations)) (VP (VBP do) (RB not) (VP (VB mate) (CC and) (VB produce) (NP (ADJP (JJ fertile)) (NN offspring)))))) (, ,) (NP (JJ separate) (NNS species)) (VP (VBP result)) (. .)))