Abstracts (first author)
Prey and predator community composition promotes polymorphic warning signals
Polymorphic warning signals are puzzling since positive frequency-dependent selection should promote monomorphic warning coloration. We studied predation pressure in the aposematic moth Parasemia plantaginis by using artificial prey resembling white and yellow male colour morphs in five separate populations. We tested if predation was influenced by: 1) natural frequencies of colour morphs; 2) number of interspecific Lepidopterans sharing similar coloration, and; 3) predator community composition. Predation on yellows was lower than whites’ regardless of their local frequency. The number of white interspecifics increased the attack risk of whites and decreased it on yellows, whereas yellow interpecifics lowered predation on both morphs. Interestingly, predation pressure was dependent on predator community composition: Yellows suffered less attacks when Paridae were abundant, whereas whites suffered less attacks when Prunellidae were abundant. Our results suggest spatial heterogeneity in prey and predator community composition can generate geographic mosaic selection facilitating the evolution of polymorphic warning signals.