ORI GIN AL PA PER Influences of geographic differentiation in the forewing warning signal of the wood tiger moth in Alaska

Abstract Aposematic organisms have warning signals advertising their unpalatability to predators, and because signal efficiency is better in higher densities, positive frequency-dependent selection is expected to select against less common signals. The wood tiger moth (Parasemia plantaginis) occurs across the Holarctic and its conspicuous hindwings serve as warning signals to predators. It also has conspicuous black and white forewing patterns that could act as warning signals, or help to hide the moth by preventing predators from seeing the outline of the moth’s body (a strategy known as disruptive coloration). In Alaska, the predominant forewing pattern changes distinctly between the regions around Fairbanks and Anchorage, suggesting local predators may maintain differences if the pattern functions as a warning signal. Alternatively, restricted gene flow along with drift could be responsible. We placed artificial moths with both local dominant and foreign forewing patterns in each of the two regions to test if predators select against the foreign forewing types, which would suggest the warning signal function of forewing patters. We also manipulated the level of disruptiveness in the forewing patterns to see if disruptive-ness works in concert with the warning signal. The locally dominant forewing type wa