Mutualistic interactions between related or unrelated species are wide- spread in ecological communities, yet their contribution to community structure is poorly understood as compared to those of other drivers such ascompetition and phylogenetic relationships. Elias et al. have studied theeffects of mutualistic interactions between neotropical ithomiine butterfly species, which form mimicry complexes with convergently evolved, brightly colored wing patterns that advertise toxicity to predatory birds. The mutualistic benefit between the butterfly species in a mimicry complex lies in the shared cost of "educating" predators. By studying 58 species in eight different complexes at a rainforest site in Ecuador, they were able to tease apart the relative effects of competition, phylogeny, and mutualism and showed that the adaptive benefits of mimicry drive increased ecological similarity between species-the opposite, in fact, from the effects of competition on community composition.
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