( ( ( Two ( fruit flies ) ) ( of ( ( different ( species mate ) ) ( but ( no offspring ) ) ) ) ) ( are ( produced c. ) ) )
(ROOT (S (NP (NP (CD Two) (NN fruit) (NNS flies)) (PP (IN of) (NP (NP (JJ different) (NN species) (NN mate)) (PP (CC but) (NP (DT no) (NN offspring)))))) (VP (VBP are) (VP (VBN produced) (NP (NN c.))))))
Two fruit flies of different species mate but no offspring are produced c.
(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)) (. .)))