Characterizing Deleterious Genomic Mutations in Simulated Populations Under Some Biologically Realistic Situations
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Authors
Li, Jian
Issue Date
2000
Volume
Issue
Type
Thesis
Language
en_US
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Abstract
The DENG-LYNCH method was developed to estimate the rate and effects of deleterious genomic mutations (DGM) in natural populations under the assumptions that populations are infinite with unlinked loci, completely outcrossing or selling, and at mutation-selection (M-S) balance. However, the population sizes of many organisms are not large enough to be considered infinite. In many plant and animal populations, selfing or outcrossing is often incomplete in that a proportion of populations undergoes inbreeding while the rest undergoes outcrossing. In addition, the degree of deviation of populations from M-S balance is often unknown. Through computer simulations, I investigated the robustness and applicability of the DENG-LYNCH method under different degrees of partial selfing/outcrossing, for non-equilibrium populations approaching M-S balance at different stages, and in finite populations with linkage disequilibrium. The investigation was implemented under constant, variable and epistatic mutation effects. I find that generally the estimation by the DENG-LYNCH method is fairly robust if the selfing rate (S) is less than 0.10 in outcrossing populations and if5 >0.8 in selfing populations. The estimation may be unbiased under partial selfing with variable and epistatic mutation effects in predominantly outcrossing populations. The estimation is also fairly robust in nonequilibrium populations at different stages approaching M-S balance and in finite populations with linkage disequilibrium. The dynamics of populations approaching M-S balance under various parameters were also studied. Under mutation and selection, generally, it takes 400-2,000 generations to reach M-S balance even when starting from homogeneous individuals free of DGM. In finite populations under constant mutation effect, U and h are unbiased or upwardly biased slightly, and s is unbiased for most cases in outcrossing populations; U and h are upwardly biased (the former is not more than 1.5 1/ and the latter is less than 1.1 h), and s is unbiased or downwardly biased slightly in highly selfing populations. Under variable mutation effects, U ranges from 0.56 to 0.72 U, and s from 1.4 to 1.8 s . My investigation provides a basis for characterizing DGM in partial selfing or outcrossing populations, nonequilibrium populations, and finite populations with linkage disequilibrium.
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Creighton University
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