Self-serving punishment of a common enemy creates a public good in reef fishes.
A key challenge for evolutionary biologists is to determine conditions under which individuals benefit from a contribution to public goods [1, 2]. For humans, it has been observed that punishment of free riders may promote contributions [3, 4], but the conditions that lead to stable cooperation based on punishment remain hotly debated [5-8]. Here we present empirical evidence that public goods may emerge as a by-product of self-serving punishment in interactions between coral reef fishes and parasitic saber-tooth blennies that stealthily attack their fish victims from behind to take a bite [9]. We first show that chasing the blenny functions as punishment [10], because it decreases the probability of future attacks. We then provide evidence that in female scalefin anthias, a shoaling species, punishment creates a public good because it increases the probability that the parasite switches to another species for the next attack. A final experiment suggests that punishment is nevertheless self-serving because blennies appear to be able to discriminate between look-alike punishers and nonpunishers. Thus, individuals that do contribute to the public good may risk being identified by the parasite as easy targets for future attacks.
University of Neuchâtel, Institute of Biology, Rue Emile-Argand 11, 2009 Neuchâtel, Switzerland. andrea.bshary@unine.ch
Andrea
A
Bshary
Redouan
R
Bshary
D000374:Aggression; D000818:Animals; D001492:Bass / Q000502:physiology*; D001522:Behavior, Animal; D057894:Coral Reefs; D005716:Game Theory; D011235:Predatory Behavior; D011678:Punishment; D012919:Social Behavior