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Experimental Studies of Mimicry in Some North American Butterflies: Part II. Battus philenor and Papilio troilus, P. polyxenes and P. glaucus
Jane Van Zandt Brower
Vol. 12, No. 2 (Jun., 1958), pp. 123-136
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2406023
Page Count: 14
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1) This paper is the second in a series of three which describe experimental studies of mimicry in some North American butterflies. 2) Seven caged Florida Scrub Jays (Cyanocitta coerulescens coerulescens) were used as predators in feeding experiments designed to test the effectiveness of mimicry in the butterflies Battus philenor (model) and the presumed mimics, Papilio troilus, P. polyxenes, and the black female form of P. glaucus. The butter-flies were immobilized and their wings were folded together dorsally, so that only mimicry in the characters of the underside of the wings was being tested. 3) The three experimental birds ate all the non-mimetic butterflies, which were offered in couplet with each model or mimic presented. Because the mimics proved to be completely palatable to the control birds, these birds were not offered the edible, non-mimetic butterflies in the present experiments. 4) The model B. philenor was unpalatable to all three experimental birds. 5) After successive trials with the model, the mimic, P. troilus, was offered to the experimental birds in place of the model. Two of the three experimental birds did not discriminate P. troilus from B. philenor. The third experimental bird ate P. troilus. However, this bird then lost its ability to reject B. philenor on sight alone, which indicated that discrimination by sight was not effective between the mimic and model. 6) When P. polyxenes was given, it was not discriminated from the model, B. philenor, by the same two experimental birds which had failed to recognize P. troilus as different from B. philenor. The third experimental bird apparently did discriminate P. polyxenes from B. philenor. 7) When the black female form of P. glaucus was given in place of the model, it was apparently discriminated by two of the three experimental birds. The third bird, in this case, did not discriminate P. glaucus from B. philenor. 8) The same characteristic behavior that had been shown by the experimental birds toward the Monarch and the Viceroy was again evident when B. philenor and its mimics were presented. 9) The four control birds, which never were given the model, found P. troilus, P. polyxenes, and the black female form of P. glaucus palatable; the mean time which each control bird took to seize P. troilus also indicated that it was particularly palatable. 10) A comparison of the reaction of the experimental and control birds to P. troilus, and a comparison of their reaction to P. polyxenes, both gave values for P of less than .001. The significant difference in response in each case is attributed to the fact that the experimental birds had experience with models before receiving the mimics. The unpalatability of B. philenor was associated with its color pattern; the birds then could not discriminate or confused the color pattern of the mimics with that of the model. Under the conditions of the experiment, the effectiveness of mimicry in P. troilus and P. polyxenes has been demonstrated, and both have been shown to be Batesian mimics. 11) A comparison of the reaction of the experimental and control birds to the black female form of P. glaucus, on the basis of a small number of trials, showed no significant difference between the two sets of birds in their treatment of this butterfly, but the possibility of the mimicry of B. philenor by P. glaucus was clearly suggested by the experiments. Explanations of the discrimination of P. glaucus from B. philenor by two of the three experimental birds have been given.
Evolution © 1958 Society for the Study of Evolution