Aposematic Variation and the Evolution of Warning Coloration in Mammals

摘要

Aposematic prey animals use conspicuous, high contrast color patterns to warn potential predators that they possess a defense mechanism. Avian predators show an innate phobia of bold, contrasting color patterns, and can readily learn to avoid a prey item displaying bold warning coloration. Signal uniformity is important to promote predator learning and memory retention; however, there is documented variation in the aposematic pattern of many species, including the striped skunk (Mephitis mephitis). Most of the literature on aposematism refers to studies using avian predators and insect prey -- we know relatively little about how mammalian predators learn about and interact with aposematic prey, despite the recognized influence of predation on the evolution of aposematism in mammals. This study examined the behavior of coyote (Canis latrans) subjects during interactions with baited black-and-white models that were able to spray a dilute skunk oil solution. Coyotes are the most common mammalian predator of striped skunks. To test their ability to generalize, after being sprayed coyotes were introduced to a variant model design based on natural documented variation in striped skunk pelage. The results demonstrate that coyotes show innate wariness of a black-and-white striped model, and most can effectively learn to avoid the model after being sprayed. Variants with proportionately more white incited more avoidance behaviors than darker patterns, although they did not allow for greater signaling power than the diagnostic black-and-white striped pattern.