The rate of spontaneous mutation for life-history traits in Caenorhabditiselegans

Spontaneous mutations were accumulated in 100 replicate lines of Caenorhabd itis elegans over a period of similar to 50 generations. Periodic assays of these lines and comparison to a frozen control suggest that the deleteriou s mutation rate for typical life-history characters in this species is at l east 0.05 per diploid genome per generation, with the average mutational ef fect on the order of 14% or less in the homozygous state and the average mu tational heritability similar to 0.0034. While the average mutation rate pe r character and the average mutational heritability for this species are so mewhat lower than previous estimates for Drosophila, these differences can be reconciled to a large extent when the biological differences between the se species are taken into consideration.