In the mutation accumulation experiments of Dee Denvers and colleagues (2004)with Caenorhabditis elegans,deleterious mutations were observed to accumulate at a slow but steady rate when the populations were grown in a benign environment,with optimal temperature and humidity,minimal crowding of individuals,abundant food,and no predators or parasites.Control lines grown under normal conditions did not accumulate mutations at the same rate.After 240 generations,experimental lines that had accumulated substantial mutations were removed from the benign environment and these lines were propagated.Explain the results once the recovery lines were established,and how this experiment demonstrates the significance of natural selection in the evolutionary process.