Darwinian a. : Pertaining to Darwin; as, the Darwinian theory, a theory of the manner and cause of the supposed development of living things from certain original forms or elements.

Darwinian n. : An advocate of Darwinism.

Example:
How can the Darwinian concept of descent with modification explain the evolution of such complex structures a?

Taxonomy
Darwinism, evolution, Darwin, Charles Darwin, natural selection, evolutionary theory, Social Darwinism, Universal Darwinism, Darwinian, Neural Darwinism, free encyclopedia, theory, mechanism, 06-19, 2007-01-04, 19th Century, evolutionary theories, sole mechanism.

Defination from the web:
... was, in its day, synonymous with "Darwinism" — the application of Darwinian principles of "struggle" to society, usually in support of anti-philanthropic ... How to be Anti-Darwinian". TalkOrigins Archive. http://www.talkorigins.org/faqs/anti-darwin.html. Retrieved 2008-06-19. ...