Self-dependence of the Mutation Rate

University Of Florida, Gainesville FL

Investigators

Abstract

The goal is to determine whether the rate at which heritable mutations occur in an organism's genome depends on the number of mutations that are already present. It was previously demonstrated that different stocks of nematodes in which mutations accumulated for 200 generations experienced different rates of decline in reproductive rate ("fitness"). The process will be repeated for a further 135 generations on a subset of these stocks with high and low fitness. If the mutation rate depends on the current mutational status, low fitness stocks will decline more rapidly than high fitness stocks. A complication is that the effect of a mutation on fitness may depend on the number of mutations already present, whereby the cumulative effects of mutations do not equal the sum of the individual effects. To distinguish between the two possibilities, the genomes of representative stocks will be sequenced, directly establishing the relationship between current mutational status and future mutation rate. The mutation rate is usually considered a fixed property of a species, but if the mutation rate depends on the number of mutations already present, there are important consequences for conservation biology, agriculture, and medicine. For example, a temporary increase in the level of a mutagenic pollutant in the environment could have lasting effects on the mutation rate even after the pollutant was removed from the environment. Understanding the relationship between current and future mutational status will enable prediction of the future consequences of environmental factors that increase the mutation load in the short term.