A mimic without its model - geographic variation in viceroy butterfly chemical defenses, palatability, and mimicry

Mimicry is an anti-predator defense, dependent on the prey’s ability to convey to the predator that it is undesirable to consume. This defensive strategy exists across a continuum; at one end of the continuum a prey species (mimic) dupes the predator by resembling a different model species (Batesian mimicry). At the other end of the continuum, two or more unprofitable prey species share the cost of predator education by resembling each other (Mullerian mimicry). Where a given mimicry system falls on this continuum and how it subsequently evolves is dependent on variation in prey noxiousness. In many mimicry systems, prey noxiousness is diet derived, yet the impacts of other ecological circumstances such as community context remain unknown. Here I explore the role of model abundance, mimic abundance, mimic defensive chemistry and mimic diet chemistry on the mimicry continuum. The abundance of queen butterflies (model) in a community decreases both the noxiousness and chemical defenses of viceroy butterflies (mimic). In areas of high queen abundance, viceroys have high palatability and low chemical defenses while in areas of low queen abundance, viceroys have lower palatability and greater chemical defenses. However, the chemical composition of the sources of viceroy chemical defense (the larval host plant) remains constant across communities. These results indicate selective pressures across communities such as non-trophic interactions have distinct outcomes in producing a mimicry continuum. Thus, the large scale spatial dynamics of mimicry relationships may facilitate the evolution of honest warning coloration in the viceroy.