This Week's Citation Classic

Dawkins R and Krebs JR. Arms races between and within species. Proc. R. Soc. Lond. B 205, 489-511 (1979)

Back in the old days before Richard Dawkins was an atheist gadfly, he did some interesting work in behavioral ecology, particularly among digger wasps. One of my favorite (and most cited) Dawkin's paper is Arms Races Between and Within Species, which he published with the estimable Lord Krebs. (There was a time when Behavioural Ecology was my favorite book in the world). The paper is very accessible, even for someone not schooled in the jargon-dense field of biology.

"Arms races" are evolutionary short hand for the coevolutionary adaptation, counter-adaptation struggles that occurs between competing entities. The term derives from the Cold War struggle between the US and the USSR where every move by the US (deploying missiles say) was countered by a similar move by the USSR.

Dawkins and Krebs's paper was one of the first to popularize the metaphor in an evolutionary context. It was, and still is, an exceptionally powerful idea and can be applied to a great number of contexts. The crux of their argument is that organisms do not respond to the physical environment alone, but rather to all the abiotic and biotic components of their habitat.

Dawkins and Kreb's cite Darwin as one of the first progenitors of the idea,

"'. . .the structure of every organic being is related, in the most essential yet often hidden manner, to that of all the other organic beings, with which it comes into competition for food and residence, or from which it has to escape, or on which it preys. This is obvious in the structure of the teeth and talons of the tiger; and in that of the legs and claws of the parasite which clings to the hair on the tiger's body. But in the beautifully plumed seed of the dandelion, and in the flattened and fringed legs of the water-beetle, the relation seems at first confined to the elements of air and water. Yet the advantage of plumed seeds no doubt stands in the closest relation to the land being already thickly clothed with other plants; so that the seeds may be widely distributed and fall on unoccupied ground. In the water-beetle, the structure of its legs, so well adapted for diving, allows it to compete with other aquatic insects, to hunt for its own prey, and to escape serving as prey to other animals.'"

An important point made by Dawkins and Krebs is that arms races are often asymmetrical, as epitomized by the Life-Dinner principle. In this metaphor, the Rabbit runs faster than the Fox since the Rabbit is running for its Life whereas the Fox is running only for Dinner. Dawkins and Krebs suggest that this can lead to species extinction. As they write in the conclusion,

"...the arms race concept may help to resolve the old controversy over whether lineages drive themselves to extinction through progressive evolution. The orthogenetic idea that evolution has its own inexorable internal momentum forcing lineages beyond the limits of natural selection is obviously absurd. Rut orthodox natural selection, if there is an arms race, can generate the kind of runaway process that looks like orthogenesis, and which might eventually hasten extinction of the lineage."

I find it interesting that Dawkins, one of the most prominent proponents of genic selection, appears here to be advocating for species selection.