Effect of model strength on predationof Batesian models and mimics.

Certain species in nature have evolved characteristics that provide protection from predators. Batesian mimicry is a system that describes a model/mimic relationship, in which a palatable organism phenotypically resembles an unpalatable organism. The effectiveness of the mimicry system may depend on the strength of toxicity in the models. We investigated the relationship between model strength and benefit to models and mimics by presenting both palatable and unpalatable artificial worms to foraging birds. The strength of the model was varied in order to determine what type of relationship occurred between model strength and benefit received by models and mimics. The type of relationship (i.e. linear, exponential, etc.) has implications as to how model strength has evolved over time. An inverse exponential relationship revealed the best fit model for our data with the most significant results. Our results therefore suggest that model strength would evolve via natural selection in a system that provides the most benefit to models relative to incremental increase in model strength, as seen in an inverse exponential relationship.