( ( ( introduction ( of ( exotic species ) ) ) ( -LRB- ( ( ( e.g. ( , ( other species ) ) ) ( of snails ) ) -RRB- ) ) ) ; )
(ROOT (NP (NP (NN introduction)) (PP (IN of) (NP (JJ exotic) (NNS species))) (PRN (-LRB- -LRB-) (NP (NP (JJ e.g.) (, ,) (JJ other) (NNS species)) (PP (IN of) (NP (NNS snails)))) (-RRB- -RRB-)) (: ;)))
introduction of exotic species (e.g., other species of snails);
(ROOT (S (NP (JJ Exotic) (NNS species)) (VP (VBP are) (ADVP (RB also)) (VP (VBN called) (NP (JJ invasive) (NNS species)) (SBAR (IN because) (S (NP (PRP they)) (VP (VBP threaten) (NP (JJ other) (NNS species))))))) (. .)))