ecology vs systematics

ecology

noun
  • The branch of biology dealing with the relationships of organisms with their environment and with each other. 

systematics

noun
  • The systematic classification of a branch of science, especially the classification of organisms. 

  • A branch of Christian theology that formulates an orderly, rational, and coherent account of Christian beliefs. It comprises dogmatics, ethics and philosophy of religion. 

  • The place where legal provisions stand as relevant for their interpretation. 

  • The study of classification systems and nomenclature. 

How often have the words ecology and systematics occurred in a corpus of books? (source: Google Ngram Viewer )