The mean genome-wide rate of fixation of deleterious mutations per generation, calculated over a time interval generations, as a function of genome size () for various recombination lengths (). This is shown for (A) low () and (B) high () LGT rates. Similarly, the rate of fixation of deleterious mutation per locus per generation is shown, again for (C) low () and (D) high () LGT rates. As genome size increases, LGT becomes less effective in reducing the mutational burden of a population. An increase in recombination length improves the efficiency of LGT in preventing the accumulation of mutations, but this beneficial effect declines rapidly with genome size. Only if recombination length is of the same order of magnitude as genome size () and the rate of LGT is high () can large genomes be maintained in a mutation-free state. Parameters: , , , . Error bars show the standard deviation over 50 independent iterations.