Why did industrial melanism in the peppered moth, Biston betularia, help convince researchers that the intensity of natural selection can be very strong? The dark-colored morph drove the light-colored morph to extinction. Birds were unable to prey on the moths once they acquired their color adaptations. The moth population exploded, covering England with moths during the Industrial Revolution. The dark-colored allele increased in frequency very rapidly in multiple populations and later decreased rapidly after the environment changed. Natural selection maintained constant proportions of the color alleles in the population, despite rapid environmental change brought about by the Industrial Revolution. Which of the following is a definition of fitness, in the context of evolutionary biology? The quality of being able to fulfill a particular role or task The fecundity of a genotype The condition of being physically fit and healthy The viability of a genotype The average lifetime contribution of individuals with a particular genotype to a population A population carries two alleles at a locus. One allele has a miniscule fitness advantage. What is the long-term fate of the locus if natural selection is the only important evolutionary force? Eventually the beneficial allele will be fixed by natural selection. Both alleles will remain in the population at a ratio proportional to the fitness difference. The population size will increase. The population size will decrease. The allele at a disadvantage will mutate to improve to the fitness level of the other allele.