1308.0962 (Sona John et al.)

Effect of linkage on the equilibrium frequency of deleterious mutations    [PDF]

Sona John, Kavita Jain

We study the evolution of an asexual population of binary sequences of finite length in which both deleterious and reverse mutations can occur. Such a model has been used to understand the prevalence of preferred codons due to selection, mutation and drift, and proposed as a possible mechanism for halting the irreversible degeneration of asexual population due to Muller's ratchet. Using an analytical argument and numerical simulations, we study the dependence of the equilibrium fraction of deleterious mutations on various population genetic parameters. In contrast to the one-locus theory, where the fraction of disadvantageous mutations decreases exponentially fast with increasing population size, we find that in the multilocus model, it decreases to zero exponentially for very large populations but approaches a constant for smaller populations logarithmically. The weak dependence on the population size may explain the similar levels of codon bias seen in populations of different sizes.

View original: http://arxiv.org/abs/1308.0962