( ( This ( helps ( explain ( why ( ( the ( jawed vertebrates ) ) ( are ( ( the ( only species ) ) ( that ( have ( ( ( ( a ( second ( , ( adaptive ( immune system ) ) ) ) ) , ) ( ( in addition ) to ) ) ( ( the ( innate ( immune system ) ) ) ( that ( ( all ( other species ) ) have ) ) ) ) ) ) ) ) ) ) ) ) ) ( , ( &#34; ( ( says ( ( Schatz , ) ( an immunologist ) ) ) . ) ) ) )
(ROOT (S (S (NP (DT This)) (VP (VBZ helps) (VP (VB explain) (SBAR (WHADVP (WRB why)) (S (NP (DT the) (JJ jawed) (NNS vertebrates)) (VP (VBP are) (NP (NP (DT the) (JJ only) (NN species)) (SBAR (WHNP (WDT that)) (S (VP (VBP have) (NP (NP (DT a) (JJ second) (, ,) (JJ adaptive) (JJ immune) (NN system)) (, ,) (CONJP (IN in) (NN addition) (TO to)) (NP (NP (DT the) (JJ innate) (JJ immune) (NN system)) (SBAR (IN that) (S (NP (DT all) (JJ other) (NN species)) (VP (VBP have)))))))))))))))) (, ,) (NP (CD &#34;)) (VP (VBZ says) (NP (NP (NNP Schatz)) (, ,) (NP (DT an) (NN immunologist)))) (. .)))
This helps explain why the jawed vertebrates are the only species that have a second, adaptive immune system, in addition to the innate immune system that all other species have,&#34; says Schatz, an immunologist.
(ROOT (S (NP (NNS Vertebrates)) (VP (VBP are) (ADJP (JJ unique) (PP (IN in) (S (VP (VBG having) (S (NP (NP (JJ adaptive) (NN immunity)) (PP (IN in) (NP (NN addition)))) (VP (TO to) (VP (VB innate) (NP (NN immunity)))))))))) (. .)))