PARENT SESSION
Poster Session 29: Predator / Prey Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Induced defenses in Hyla chrysoscelis (Amphibia:Hylidae): plasticity response gradient and interspecific cue recognition.
Richardson, Jonathan2, 2 University of Washington, Seattle, Washington, USA
ABSTRACT- Organisms in aquatic ecosystems must often tolerate variable environmental conditions, including an uncertain risk of predation. Individuals that can maintain plastic defenses against predation will increase their survival when predators are present, but they will not incur the costs of these defenses when the risk of predation is low and the defense is not induced. The pond-breeding anuran Hyla chrysoscelis develops a very conspicuous phenotype in the presence of predators consisting of a brightly colored yellow and red tail with black spots, as well as a deep tail fin. I attempted to identify the source of the chemical signal that induces this defensive morphology in tadpoles of this species. I tested whether metabolites alone, originating from the prey but passing through the predator, were able to induce the same morphological response as the combination of metabolites and alarm signals coming directly from conspecifics. I used morphometric data, in addition to tail conspicuousness variables, to assess tadpole response to the perceived risk of predation. I also tested whether this inducing cue could be recognized across species by measuring the morphological response of H. chrysoscelis tadpoles exposed to cues emitted when tadpoles of a closely related genus (Pseudacris crucifer) were eaten by predators. Tadpoles exhibited a graded response of tail morphology in response to all cues. Responses of both tadpole shape and tail conspicuousness to indicators of a risk of predation were significantly greater than responses to control conditions. Hyla tadpoles were also able to respond to cues emitted when tadpoles of a closely related genus were consumed by predators. This suggests that inducing cues may be conserved across anuran lineages, and that interspecific communication for predator avoidance may be common in amphibians and other aquatic fauna.
Key words: inducible defenses, phenotypic plasticity, Hyla, Alarm signals