Melanism in the Two Spot Ladybird: The Nature and Intensity of Selection

E. R. Creed
1975 Proceedings of the Royal Society of London. Biological Sciences  
Intraseasonal changes in the melanic frequency of Adalia have been recorded in and around Berlin and Birmingham; in the latter place a steady decrease in frequency has also occurred over several years. E sti mates of the intensity of natural selection have been made from the observed changes in frequency. Selection against black individuals in winter, and against red ones in summer, appears to be higher in Berlin (52 % against black heterozygotes in winter and 33 % against red homo zygotes in
more » ... d homo zygotes in summer) than in Birmingham (24 and 9 % respectively); there are indications th a t mean maximum summer temperature and mean minimum winter temperature influence the intensity of selection, as do local smoke pollution levels, but not sulphur dioxide (as with Biston betularia). In some parts of the ladybird's geographical range, increased mating activity of the black individuals may also be important.
doi:10.1098/rspb.1975.0083 fatcat:yeyauktvvbakvjikdixizruek4