The original source of new alleles, upon which selection operates, is
mutation, a random event that occurs without regard to selectional value in
the organism. Although many model organisms have been used to study mutational
events in populations, some investigators have developed abiotic molecular
models. Soll (2006) examined one such model to study the relationship between
both deleterious and advantageous mutations and population size in a ligase
molecule composed of RNA (a ribozyme). Soll found that the smaller the
population of molecules, the more likely it was that not only deleterious
mutations but also advantageous mutations would disappear. Why would
population size influence the survival of both types of mutations (deleterious
and advantageous) in populations?