( ( ( ( Animals , ) ( which ( ( ( ( live ( within ( a ( same-species group ) ) ) ) , ) and ) ( ( occupy ( an area ) ) ( at ( the ( same time ) ) ) ) ) ) ) , ) ( ( are ( part ( of ( a population ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Animals)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VP (VB live) (PP (IN within) (NP (DT a) (JJ same-species) (NN group)))) (, ,) (CC and) (VP (VB occupy) (NP (DT an) (NN area)) (PP (IN at) (NP (DT the) (JJ same) (NN time))))))) (, ,)) (VP (VBP are) (NP (NP (NN part)) (PP (IN of) (NP (DT a) (NN population))))) (. .)))
Animals,          which live within a same-species group, and occupy an area          at the same time, are part of a population.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT a) (NN group)) (PP (IN of) (NP (NP (NNS organisms)) (PP (IN of) (NP (DT the) (JJ same) (NN species)))))) (SBAR (IN that) (S (VP (VBP live) (PP (IN in) (NP (DT the) (JJ same) (NN area)))) (NP (DT a) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN population))))) (. .)))