How do density dependent dynamics influence the efficacy of mimetic signaling?

Trustees Of Boston University, Boston

Investigators

Abstract

Mimicry is a classic example of evolutionary adaptation where organisms gain a selective benefit by resembling a different species. In cases of Batesian mimicry, palatable mimics gain protection from predation by co-opting an unpalatable model’s signal to potential predators. Evolutionary theory predicts that any mutation that improves the resemblance between the model and mimic should be favored by natural selection. Therefore, the widespread occurrence of mimetic polymorphism, the conspicuous variance in mimetic perfection, and the existence of apparently static imperfect mimetic signals is puzzling. Although numerous hypotheses have been proposed to explain these puzzling phenomena, recent research in this field suggests that any factor that reduces a predator’s ability to predict which potential prey items are toxic will lead to relaxed selective pressure on imperfect mimics. Here, the researchers test the hypothesis that density dependent effects, alone or in concert with frequency-dependent effects, increase predator uncertainty and cause relaxed selection on imperfect mimetic traits. Researchers will also partner with K-12 STEM teachers to improve outreach to public schools. Although the importance of frequency-dependent dynamics is well established in the mimicry literature, questions remain about their relationship to the evolution of imperfect mimicry and the paradox of mimetic polymorphism. Finding evidence of density dependent effects would be significant for at least two reasons. First, it would improve understanding of the factors governing predator behavior. This is important because predator communities likely vary significantly across both spatial and temporal scales. Therefore, understanding how variation in prey density and abundance influences predator learning is crucial to predicting the conditions under which imperfect mimicry is expected to persist. Second, density effects provide an intuitive hypothesis for the maintenance of polymorphic mimicry because spatial and/or temporal variance in the absolute or relative density of multiple, unpalatable models within a given predator community is expected to generate a heterogeneous fitness landscape for palatable mimics that could lead to the origin of, or further divergence between, polymorphic forms. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.