Evolutionary conflict can drive rapid adaptive evolution, sometimes called an arms race, because each party needs to respond continually to the adaptations of the other. Evidence for such arms races can be seen in morphology, in behavior, or in the genes underlying sexual interactions or host-pathogen interactions. ~ American evolutionary biologist Katherine Geist
Resource allocation trade-off has influenced the evolutionary diversification of weapons, revealing a rich interplay between developmental trade-offs and both pre- and post-mating mechanisms of sexual competition. ~ Australian evolutionary biologist Leigh Simmons & American zoologist Douglas Emlen
Evolutionary arms races often occur. A typical example are male animals that produce ever-spectacular weapons to fight off rivals and secure a mate. Antlers and tusks are exemplary.
3 preconditions appear necessary for adaptive arms races to reach extremities. 1st, there must be competition for a limited resource, typically access to reproductive females. 2nd, the resource must be confined in a way that its access is largely defensible by an animal. 3rd, males fight one-on-one for the right of access. Where guerilla tactics may succeed does not lead to the evolution of extreme bioweapons.