Survival of fathead minnows after injury by predators and its possible role in the evolution of alarm signals

Synopsis Some mechanisms proposed to account for the evolution of animal alarm signals require that the signal sender survive in order to benefit. The ostariophysan alarm pheromone system requires mechanical damage for the release of the alarm pheromone. A natural situation is described in which up to 16% of the fathead minnows in a population have survived damaging encounters with predators. This indicates that post-signal selective benefits can operate in the evolution of the ostariophysan alarm system.