There is a very interesting piece in the Chronicle of Higher Education by Simon Levin on the "Evolution of Ecology."
See The Evolution of Ecology - The Chronicle Review - The Chronicle of Higher Education
In it Simon, who I consider both a friend and colleague and who has been an inspiration to me for much of my work, discusses the history of the concept and the field of ecology. He repeats a key phrase he has used elsewhere:
Ecology, the unifying science in integrating knowledge of life on our planet, has become the essential science in learning how to preserve it.
I like this phrase and plan to use it a bit here and there, with attribution of course.
Levin also discusses how Darwin's Voyage of the Beagle helped launch the field of ecology because it
defined a new and synthetic way of looking at nature—in which the patterns characteristic of particular regions found explanation in a unifying, dynamic framework
It was only after Voyage of the Beagle and Wallace's work and others that the term "oekologie" came into being.
I particularly like the end where he connects ecology to study of other complex adaptive systems like economic ones and medical ones.
The article is really really really worth a read.