“…When neighboring populations of a species are compared, one finds that they usually differ from one another, slightly or appreciably, in a number of characteristics, eg, size, color or any other morphological or physiological character (Halkka et al, 1975;Rhomberg and Singh, 1989). Huxley (1942) Adh, a-Gpd, G-6-pd, Odh, 6-Pgd, Aph, Est-C, and Mdh (Voelker et al, 1977(Voelker et al, , 1978Anderson, 1981;Oakeshott et al, 1981Oakeshott et al, , 1982David, 1982;Anderson and Oakeshott, 1984). The seasonal cycle in Mpi and the latitudinal clines of other loci suggest that alternative alleles have different optimal temperatures or other environmental variables (see also Tomiuk and Wohrmann, 1984).…”