“…He coordinated country-wide surveys of morph frequency (1958 and 1965), which became the standard to compare earlier and later work, and produced the first convincing evidence that birds eat the moths and could do so selectively (Kettlewell, 1955). Following his example, other authors tested for selective predation with moths of different phenotypes exposed on trees to be eaten (Clarke and Sheppard, 1966;Bishop, 1972;Lees and Creed, 1975;Whittle et al, 1976;Steward, 1977a;Bishop et al, 1978;Murray et al, 1980;Howlett and Majerus, 1987). Overall, these experiments suggested that the melanic peppered moth had an advantage of up to 2 to 1 over the typical form in industrial locations, where melanic frequency was 80 per cent or more, but a disadvantage, sometimes large, where the frequency was lower.…”