as the heterozygous advantage, in which a bank of recessive alleles becomes favored due to a change in the environment. The biological significance of melanism was a matter for debate for some decades, and although it is now generally accepted that melanism in (f. typical) is associated with atmospheric pollution, some of the details are still unclear. Although several points are worth emphasizing. Pollution in this instance is not having a direct effect on the moth populations, nor indeed on their predators, but an alteration to the habitat has altered greatly the relative fitness of different genotypes. Melanism also illustrates the difficulty of producing adequate proof, or disproof, of cause and effect when pollutants are thought to be causing major biological effects. In conclusion, with regards to genetics, it is important to appreciate that the effects of pollutants can be modified by an organism’s genetic constitution, and that pollutants can alter a population's gene pool (Freeman, 128). The interactions between pollutants and genes can be relevant both to understanding and to predicting effects and are potentially of great value for monitoring (Moriarty, 102).In summary, as stated throughout this school year in my 2375 Pollution class, the effects of pollutants on populations are mediated via their effects, direct or indirect on individuals and the likelihood of these effects depends on the dose. Sublethal effects can be unraveled from knowledge of the mode of action. Alternatively, emphasis in the study of sublethal effects can be placed on the health of the individual organism. With both approaches, the effect of other environmental variables needs to be given much more prominence than heretofore and this could profitably be linked with studies on amounts of pollutant within organisms (Moriarty, 176). It is from this basis that Moriarty states that we have to consider how best to predict and to monitor the ecological e...
