Meeting Abstract

63.6  Wednesday, Jan. 6  Evolution of bribery in a diffuse cleaning mutualism LETTIERI, Liliana*; STREELMAN, J. Todd; Georgia Institute of Technology; Georgia Institute of Technology liliana@gatech.edu

Most examples of tolerance traits come from plant-herbivore and host-parasite systems. The mutualism between Caribbean cleaner gobies and their many client fish species appears to provide the first vertebrate animal example of using a set of traits that reduced the costs of interactions with risky individuals. Novel blue stripes in some species “bribe” predators to become clients that receive parasite-cleaning services in turn providing a reliable alternative food source for the gobies. Our results highlight evolutionary changes from predator resistance traits (camouflaged colors within aposematic patterns) to tolerance traits (conspicuous advertising stripes and chemically mediated attack reduction). These shifts were most likely driven by the sensory and learning biases of a large suite of piscivorous reef fish species. In field trials, stereotypical client posing behaviour and antagonistic attack occurrences varied inversely among control, yellow, and blue striped models, with blues receiving more posing and fewer attacks. In addition, wild caught cleaners deterred predation in feeding trials, surviving more often and for longer when enclosed with small predatory fishes. Notably, cleaner status was a significant predictor of survival, and blue cleaners were spit out more often than other goby species. Blue cleaners are also more likely to service piscivorous clients than yellow and green basal species. We propose Elacatinus gobies have evolved in a repeated adaptive fashion to promote interactions with risky clients, while pre-existing adaptations deter attacks and reduce costs. The key innovation of “bribery” has mediated this shift from conflict to cooperation via tolerance. Similar trajectories of evolution from resistance to tolerance may occur in other diffuse mutualisms.