Today’s metaphor comes from the beginning of the third chapter of Charles Darwin’s Origin of Species (1859), where Darwin asks his Victorian readers to think of nature, not as might be customary for them on a summer stroll—as a place of abundance and “bright with gladness”—but as a place where animals and plants are actually struggling with one another for access to scarce resources:
We behold the face of nature bright with gladness, we often see superabundance of food; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that though food may be now superabundant, it is not so at all seasons of each recurring year.
Scarcity of resources is central to Darwin’s argument for evolution by natural selection, and he calls his theory:
[T]he doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms.
For a discussion of economic Malthusianism applied by Darwin in analogy with biological evolution, see here: https://santitafarella.wordpress.com/2008/07/28/evolution-v-creation-metaphor-watch-is-the-struggle-for-existence-economic-malthusianism-writ-large/