CHARACTERIZATION OF DELETERIOUS MUTATIONS IN OUTCROSSING POPULATIONS

Deng and Lynch recently proposed estimating the rate and effects of de leterious genomic mutations from changes ill the mean and genetic vari ance of fitness upon selfing/outcrossing in outcrossing/highly selfing populations. The utility of our original estimation approach is limit ed in outcrossing populations, since selfing may not always be feasibl e. Here we extend the approach to any form of inbreeding in outcrossin g populations. By simulations, the statistical properties of the estim ation under a common form of inbreeding (sib mating) are investigated under a range of biologically plausible situations. The efficiencies o f different degrees of inbreeding and two different experimental desig ns of estimation are also investigated. We found that estimation using the total gene tic variation in the inbred generation is generally mo re efficient than employing the genetic variation among the mean of in bred families, and that higher degree of inbreeding employed in experi ments yields higher power for estimation. The simulation results of th e magnitude and direction of estimation bias under variable or epistat ic mutation effects may provide a basis for accurate inferences of del eterious mutations. Simulations accounting for environmental variance of fitness suggest that, under full-sib mating, our extension can achi eve reasonably well an estimation with sample sizes of only similar to 2000-3000.