Nothing in biology makes sense except in the light of evolution.” Dobzhansky’s (1964, 449) sweeping generalization is provocative but also partial. Ecology casts the same indispensable light in biology, particularly on evolution. Nowhere is this clearer than in the origin of evolutionary theory. Although the term “ecology” was not coined until 1866 (Haeckel 1866), ecological insight is at the core of Darwin’s theory. It is reflected both in the theory’s concepts – for example, adaptation and natural selection – and in its compelling accounts of biological phenomena, such as the transmutation of species and the fit between organisms and environments. That evolutionary biology’s chief architect is Darwin is well known. The foundational role his work had in ecology and that an ecological perspective underpins the theory of natural selection are less appreciated.

Reconceptualizing the Environment

Perhaps the most theoretically fertile issue at the intersection of ecology and evolution is the adaptive fit between organisms and their environment. Seeing that relationship as the key to evolutionary dynamics required a reconceptualization of how the environment impacts organisms and the environment itself.

At the turn of the nineteenth century, philosophical and scientific conceptions of the environment reflected a romantic zeitgeist. Thoreau’s Walden , for example, exemplifies the view ( Fig. 47.1). In it, organisms and their environments are coupled components of an encompassing, harmonious system, each complementing the other in a providential symbiosis. The same underlying theological commitment to a beneficent and coherent order in the living world arguably compelled the impressive systematicity (and occasional biological misstep) of Linnaeus’s classification system. But by the mid-nineteenth century a less idyllic, more brutal view of the environment was challenging the prevailing romanticism (Worster 1994 ). Tennyson’s grim characterization of nature as “red in tooth and claw” captured the new sentiment, and would find scientific expression and vindication in Darwin’s theory.