( ( A population ) ( ( is ( ( a group ) ( of ( individuals ( of ( ( the ( same species ) ) ( living ( in ( ( the ( same area ) ) ( at ( the ( same time ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN population)) (VP (VBZ is) (NP (NP (DT a) (NN group)) (PP (IN of) (NP (NP (NNS individuals)) (PP (IN of) (NP (NP (DT the) (JJ same) (NN species)) (VP (VBG living) (PP (IN in) (NP (NP (DT the) (JJ same) (NN area)) (PP (IN at) (NP (DT the) (JJ same) (NN time)))))))))))) (. .)))
A population is a group of individuals of the same species living in the same area at the same time.
(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.