( ( Allopatric speciation ) ( ( occurs ( when ( ( a ( new species ) ) ( arises ( in ( ( a ( geographic area ) ) ( that ( is ( isolated ( from ( the ( parent stock ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Allopatric) (NN speciation)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (JJ new) (NN species)) (VP (VBZ arises) (PP (IN in) (NP (NP (DT a) (JJ geographic) (NN area)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (VBN isolated) (PP (IN from) (NP (DT the) (NN parent) (NN stock))))))))))))) (. .)))
Allopatric speciation occurs when a new species arises in a geographic area that is isolated from the parent stock.
(ROOT (S (NP (JJ Sympatric) (NN speciation)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (JJ new) (NN species)) (VP (VBZ arises) (PP (IN without) (NP (JJ geographic) (NN separation))))))) (. .)))