Melanic Moth Frequencies in Yorkshire, an Old English Industrial Hot Spot

Abstract

A survey has been carried out in Leeds, England, in the west Yorkshire industrial heartland, and in neighboring York, surrounded by agriculture, of melanic frequency in the moth species Biston betularia, Odontoptera bidentata, and Apamea crenata. All show a decline in melanics in the postindustrial environment, the first over almost the full range from nearly 100% to less that 10%, the others to smaller extents. Changes in several species over as great a magnitude and as wide an area must result from selection. The results are compared with others along a transect through northern England. The onset of response is progressively later from west to east. The rate of decline is lower at the extremes of the transect to west and east than it is in the center. We still do not have a clear picture of the causes of the changes. One major factor is likely to be selective predation, which is shown to be critically dependent on predation rate. As a consequence, differences in settling behavior between the species could account for different responses even if the species are attacked by the same predators.

Decline of melanism in two British moths: spatial, temporal and inter-specific variation

“…O. bidentata melanics have never been as prevalent as those of B. betularia and fluctuated in frequency over shorter distances (Bishop et al, 1978;Cook and Jacobs, 1983). They have declined at a lower rate to frequencies that are sometimes still quite high (Cook et al, 2004(Cook et al, , 2005; this paper). Apocheima pilosaria (Denis and Schiffermü ller) is in some respects intermediate in response between these two species (Lees, 1971(Lees, , 1981Cook et al, 2002).…”

“…Similar calculations have been carried out (Table 3) for data from Manchester (data of Cook et al, 1999), Caldy, west of Liverpool (Clarke et al, 1985(Clarke et al, , 1990(Clarke et al, , 1994Grant et al, 1996), York (TJ Crawford in Cook et al, 2005, supplemented from Table 1), Cambridge (Lees and Creed, 1975;Majerus, 1998), north-west Kent (BK West, in Cook and Grant, 2000) and Nottingham (K Cooper in Cook and Grant, 2000). The estimates provide no significant evidence of change in selection over the period nor any consistent pattern of acceleration or deceleration, but most of the data sets are probably insufficiently complete to detect it.…”

“…This is 476 m away from the collecting site used by SL Sutton (SLS site, NGR 434379 439387) and previously reported (Cook et al, 2005), allowing frequencies in parallel samplings to be compared. In the peppered moth B. betularia, the black form carbonaria, intermediates insularia and the black and white typica forms are scored, and in the scalloped hazel moth O. bidentata, the melanic nigra and the pale brown nonmelanic forms are scored.…”

“…Descriptions of these phenotypes are given by Kettlewell (1973). Evidence on the number of alleles in the melanic series in B. betularia is reviewed by Cook and Muggleton (2003 (Cook et al, 2005).…”

“…When dominant morph frequency is very high, however, as at Figure 1 Frequency of the carbonaria form in Biston betularia for north Leeds. Circles: data of SLS (from Cook et al, 2005). Squares: this paper.…”