Testing  the integrated and individualistic hypotheses of communities.
   Ecologist Robert Whittaker tested these two hypotheses by graphing the
   abundance  of  different  plant  species  (y axis) along environmental
   gradients  of abiotic factors such as temperature or moisture (xaxis).
   Each colored curve represents the abundance of one species.

   Integrated   hypothesis.   Communities   are   discrete  groupings  of
   particular  species  that are closely interdependent and nearly always
   occur together. 1