I want to perform CCA, but I read that,
remember that observations (for example, species abundances) have to present unimodal distributions along gradients (for example, environmental variables). Note that if observations are, instead, linearly related to gradients, we have to use a Canonical Correlation Analysis (CANCOR) or Redundancy Analysis (RDA) instead of a Canonical Correspondence Analysis (CCA).
Source: R Functions: Canonical Correspondence Analysis: CCA and Partial CCA
Which exploratory data analysis I can carry out (preferably in
R) to be sure that my data are suitable for CCA?