Mutations are supposed to play an important role in evolution. On a per-nucleotide basis, mutation rates have been found to be very small. Moreover, the genomes are sufficiently large. However, every individual carries a number of new mutations. Some of these are lethal. Typically, even more are neutral or nearly so. Most of the rest are deleterious. But some of these mutations, perhaps more than we might have expected, are beneficial to individuals. Comment on the following three hypotheses:
a. In the absence of natural selection, deleterious mutations accumulate and the average fitness of populations decline. With natural selection, however, beneficial mutations can accumulate and mean fitness can rise.
b. Organisms exposed to adverse environmental conditions display greater rates of mutation.
c. Mutation rates vary depending on the loci in a genome