Alarm signals predator attraction

Mathis, A., Chivers, D.P. R.J.F Smith. 1995. Chemical alarm signals predator-deterrents or predator attractants Am. Nat., 145, 994-1005. 

Chivers DP, Brown GE, Smith RJF (1996) The evolution of chemical alarm signals attracting predators benefits alarm signal senders. Am Nat 148 649-659... 

The variety of functional niches occupied by these injury-released compounds suggests conflicts between the requirements of various functions . Selection on senders and receivers may each exert pressure on the system. For example, predator attraction as a defense mechanism may conflict with abrasive spawning behavior and resistance to digestive processes may conflict with optimal breakdown rates for alarm signaling. 

Predator attraction as a strategy favoring senders would favor chemical secretions that were easily detected by predators. Both alarm signaling and predator attraction should favor easy detection. However, there could be conflict between attracting predators and repelling conspecifics, so a compound or mix of compounds that was a general attractant or repellant would favor one function over the other. If that is so, predator attraction seems to have won out in fathead minnows. However, compounds that attract predators are best avoided by prey, increasing selection on prey for defensive responses to the cue. 

Taxonomic Comparisons. Obviously there are many variations on the basic injury released alarm pheromone theme in fishes and other organisms. A more comprehensive examination of the distribution and variations of this phenomenon might reveal patterns. For example, are there alarm substances that are predator attractants and others that are predator repellants Are some ecological niches more amenable to chemical alarm signaling than others Electrical ostariophysans, for example, seem to lack the alarm pheromone system (Pfeiffer 1977) but may use their electrical signals in some comparable manner. 

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