Genetic instability of C. elegans comes naturally.

There have been many attempts to measure the genome-wide mutation rate for spontaneous mutations, using measurements of traits in inbred lines in which mutations have accumulated. However, these are likely to miss many small-effect mutations that are important for evolutionary processes. Recently, the genome-wide spontaneous mutation rate in inbred lines of Caenorhabditis elegans was estimated, using DNA sequencing. The results imply that the mutation rate is surprisingly high, and that insertion-deletion mutations are unexpectedly common. Phenotypic assays of the same lines detected only a small proportion of mutations that were predicted to have evolutionarily significant fitness effects.