Joint publication of Ecology and Evolution of interactions (EEI) group and ESB group

Testing evolution in action with polymorphic moths and natural predators in the wild

To celebrate the integration of the Ecology and Evolution of interactions (EEI) group that recently started in Helsinki and the ESB group, we highlight a joint research article titled “Geographic mosaic of selection by avian predators on hindwing warning colour in a polymorphic aposematic moth” published in Ecology Letters . The study was based on massive field experiments by Academy professor Johanna Mappes's EEI group and an integral part of current ESB post doc Katja Rönkä’s PhD on the role of predation in maintaining aposematic polymorphism in the wood tiger moth Arctia plantaginis. Beakmarks in the plasticine bodies of thousands of little paper-winged moths spread out to Finnish, Estonian, Scottish and Caucasian wood tiger moth habitats revealed differences in predator selection following predictions from aposematism theory, yet complicated by differences in the local predator community composition monitored at the same sites. The local density of moth warning colour morphs determined their risk of being attacked, as expected if local predators have learned to avoid the most common warning signals. However, here we also found that different morphs were selected for in different regions and according to the local avian community. Therefore, supportive of Thompson’s theory on a geographic mosaic of selection, it seems that spatial and temporal variation in morph densities and local avian predator community composition alters the direction and strength of positive frequency-dependent selection, which likely enables perplexing coexistence of multiple aposematic colour morphs for extended periods of time. Together, these findings provide a nice example of how the close collaboration of EEI and ESB widen both of our thinking from individual and population level differences in behaviour to processes creating and maintaining biodiversity in space and time.