( ( ( ( ( D -RRB- ) ( ( ( A ( single clade ) ) ( -LRB- ( i.e. ( , ( ( ( ( ( a group ) ( of ( species ( that share ) ) ) ) ( a common ) ) ancestor ) -RRB- ) ) ) ) ) ( can ( exhibit ( both gradualism ) ) ) ) ) and ) ( punctuated equilibrium ) ) . )
(ROOT (S (VP (VP (VB D) (-RRB- -RRB-) (NP (NP (DT A) (JJ single) (NN clade)) (PRN (-LRB- -LRB-) (FW i.e.) (, ,) (ADJP (NP (NP (NP (DT a) (NN group)) (PP (IN of) (NP (NP (NNS species)) (NP (DT that) (NN share))))) (QP (DT a) (JJ common))) (JJ ancestor)) (-RRB- -RRB-)) (SBAR (S (VP (MD can) (VP (VB exhibit) (NP (DT both) (NN gradualism)))))))) (CC and) (VP (VB punctuated) (NP (NN equilibrium)))) (. .)))
D) A single clade (i.e., a group of species that share a common ancestor) can exhibit both gradualism and punctuated equilibrium.
(ROOT (S (NP (NNP Darwin)) (VP (VBD believed) (PP (IN in) (NP (NN gradualism)))) (. .)))