"Go-slow" Signalling and the Problem of Automimicry

Abstract

Automimicry is the existence of palatable individuals in an unpalatable, warningly coloured (i.e. aposematic) prey species. Because automimics are visually indistinguishable from their models, they present a special problem for the evolutionary stability of aposematism. Traditionally this problem has remained either unrecognized, or has been considered solved by the actions of naive predators that attack warningly coloured prey, eating them if palatable, rejecting them if unpalatable. Although naive predators can stabilize aposematism against invasion by automimics, the conditions under which they can do so are restricted. It is argued here that an adjustment to the traditional view of how aposematic signals operate can offer a more general solution to the problem of automimicry. The "go-slow signalling" solution proposes that some predators learn not to avoid aposematic prey, but to sample them cautiously in order to determine their true palatability more accurately. Because unpalatable prey can benefit by advertising conspicuously to go-slow predators, but cannot benefit by advertising to naive predators (unless predators are innately cautious of conspicuously coloured prey), go-slow signalling can stabilize aposematism under a wider range of conditions than can traditional naive predators. The assumptions, predictions, and empirical implications of the go-slow signalling hypothesis are discussed.