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Arthur S. Lodge     |     home
First replies: Wells
    (1) The figure of 168 moths cited by Thomas and Johnson is an egregious example of manipulating data to prove something the data don't show. Those numbers were taken from Tables 6.1 and 6.2 in Michael Majerus's book, Melanism: Evolution in Action (Oxford, 1998, p. 123). Observations in Table 6.2 were recorded "in the vicinity of mercury vapour traps" - i.e., they were observations of moths which Majerus himself acknowledges (on p. 121) were NOT "in truly natural positions." So the 135 + 20 figures are not natural at all. Of the 47 moths found in truly natural positions (listed in Table 6.1), only 6 were found on exposed trunks. Another 6 were found hidden in cracks, and 20 were found hidden in trunk/branch joints. But according to the classic peppered moth story, it is moths whose camouflage differences affect bird predation that matter - not moths that are obscured from the view of birds in cracks or trunk/branch joints. So the number Thomas and Johnson should be citing is 6, not 168.

    (2) Even if the correct number were 168 rather than 6, this would still represent only a tiny percentage of the tens of thousands of peppered moths studied by field researchers between the 1950s and 1990s.

    (3) I do not claim that peppered moths NEVER rest on tree trunks, but only that they do not NORMALLY rest on tree trunks in the wild. This is the conclusion of everyone who has studied the natural resting-places of peppered moths, including Majerus. In addition to the conclusions you already cite from my work, I could add the following from Majerus's book: "Peppered moths do not naturally rest in exposed positions on tree trunks.... Data on the natural resting sites of the peppered moth are pitifully scarce, and this in itself suggests that peppered moths do not habitually rest in exposed positions on tree trunks. Many nocturnal moths do rest by day on tree trunks and searching trunks has long been a recognized method of collecting employed by lepidopterists. However, the number of published records of peppered moths being found on tree trunks is negligible." (Melanism: Evolution in Action, Oxford 1998, p. 121)