"As Biston betularia has served as a paradigm of evolution, it deserves the closest possible scrutiny"
B. Grant & R. J. Howlett (1988), Biol. J. Linn.Soc. 33, 217-232
"Until now, however, the prize horse in our stable of examples has been the evolution of 'industrial melanism' in the peppered moth, Biston betularia, presented by most teachers and textbooks as the paradigm of natural selection and evolution occurring within a human lifetime....this classic example is in bad shape, and, while not yet ready for the glue factory, needs serious attention."
J. A. Coyne (1998) Nature 396, 35
"Of course, the 'classical' explanation may be true, in whole or in part. We contend, however, that there is little persuasive evidence, in the form of rigorous and replicated observations and experiments to support this explanation at the present time."
T. D. Sargent, C. D. Millar & D. M. Lambert (1998), Evolutionary Biology 30, p. 318.
"...almost all textbook photographs depicting the morphs of B. betularia on trees represent dead specimens glued to the different backgrounds."
ibid., p. 309
Arthur S. Lodge | home
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Peppered moth melanism - summary by A. S. Lodge
1. The observed high rates of change of morph populations would (if the "classical" application of the NDT were valid) require (ref. 1) a high "selection pressure" (i.e., a high rate of bird predation). Bird predation of peppered moths from their natural resting places in the wild has never been observed (ref. 2).
2.There is no published evidence that shows that random, spontaneous mutations have played any role in the first appearance of any morph (ref. 3).
3. Because the range of bird vision extends beyond the human range into the ultraviolet, human assessments of crypsis (= camouflage) are unreliable guides to birds' assessments (ref. 4).
4. The natural daytime resting places of B. betularia in the wild are not on vertical tree trunks (ref. 5).
5. Following the reduction in industrial pollution consequent on passage of clean air acts, relative populations of lighter morphs increased before lichens returned to lighten tree trunks (ref. 6).
6. The results of laboratory and other humanly contrived experiments are an unreliable guide to the natural behavior of moths in the wild (ref. 7).
7. In the wild, peppered moths normally rest with closed wings, not with wings spread out (ref.8)
8. Since 1810, both light and dark moths have existed. No new forms have appeared. There is, therefore, no evidence of evolution during this period.
9. There is no evidence that mutations have played any significant role in the increase and decrease in the dark/light ratio during the past 190 years.
1."..the speed with which melanics have replaced typicals is regarded as one of the most striking features of the industrial melanism phenomenon (Kettlewell, 1973)." T. D. Sargent, C. D. Millar, & D. M. Lambert (1998), Evolutionary Biology 30, p.303, paragraph 3.
2. "…observations of peppered moths being taken from any natural resting places are still lacking and are urgently needed." M. E. N. Majerus (1998), Melanism: Evolution in Action (Oxford University Press), p.125, paragraph 2.
3. "A typical assumption from the `classical' perspective is that these alleles have arisen as `spontaneous mutations'." Sargent et al., ibid., p.302, paragraph 1.
4. "..none of the assessments of the relative crypsis of moths as determined by humans should be applied to birds." Majerus, ibid., p.137, paragraph 2.
5. "…all we have observed is where the moths do not spend the day." C. A. Clarke, G. S. Mani, & G. Wynne (1985), Biol. J. Linn. Soc. 26, 189-199. "…individuals do not commonly rest on vertical tree trunks." Sargent et al. p.307, paragraph 1.
6. "… it is not entirely clear, even in England (e.g., Clarke et al. 1985) that lichen floras have changed appreciably, and they have certainly not done so in North America (e.g., Grant et al., 1995, 1996)." Sargent et al., p.316, paragraph 4.
7. "We feel that there is really no evidence from experimental work on background choice that supports the `classical' explanation of industrial melanism in B. betularia." Sargent et al., ibid., p.308, paragraph 3. "…Kettlewell's experiments do not prove in any acceptable way, according to the current scientific standard, the process he maintains to have experimentally demonstrated", G. Sermonti & P. Catastini (1984), Riv. Biol. 77, 35-52.
8. T. D. Sargent, inspecting photos of peppered moths in a textbook, stated, "These moths are not in a resting attitude, because the antennae are out. When they rest, they pull the antennae back under the forewings and their wings are back in a triangular state, not spread out like this." Quoted by Judith Hooper in Of Moths and Men (Fourth Estate, London UK, 2002) p.241.