This paper synthetically outlines the process that from the botanical researches, evolutionary theories, and mineral-cycles discoveries, beginning from the second half of the nineteenth century, has led to the development of ecology as an autonomous scientific discipline. At the beginning of the twentieth century, this development intersected the studies on thermodynamics and systems theories, which together with a great variety of natural, technical, and social sciences, became integrated in the constituting ecological science. From the 1950s onward, systems theory has notably constituted an important contribution in the shaping of ecology, some of whose most influential and controversial approaches, namely ecosystems ecology and global ecology, are deeply characterised by the systems theorists' influence.