( ( ( ( Population Individuals ) ( of ( the ( same species ) ) ) ) ( ( living together ) ( in ( the ( same environment ) ) ) ) ) . )
(ROOT (NP (NP (NP (NNP Population) (NNS Individuals)) (PP (IN of) (NP (DT the) (JJ same) (NN species)))) (VP (VBG living) (ADVP (RB together)) (PP (IN in) (NP (DT the) (JJ same) (NN environment)))) (. .)))
Population Individuals of the same species living together in the same environment.
(ROOT (S (NP (NP (PDT All) (DT the) (NNS members)) (PP (IN of) (NP (NP (DT a) (NN species)) (SBAR (WHNP (WDT that)) (S (VP (VBP live) (PP (IN in) (NP (DT the) (JJ same) (NN area))))))))) (VP (VBP form) (NP (DT a) (NN population))) (. .)))
All the members of a species that live in the same area form a population.