Muller's ratchet under epistatic selection.

摘要: In a finite asexual population mean fitness may decrease by process known as Muller's ratchet, which proceeds if all individuals with the minimum number of deleterious alleles are randomly lost. If these have independent effects on fitness, previous analysis suggested that rate this either remains constant or, accumulation mutations leads to decline size, grows. Here I show conclusion is quite sensitive assumption independence. synergistic effects, then, ratchet advances, frequency best available genotype will necessarily increase, making its loss less and probable. As result, sufficiently strong epistasis can effectively halt action ratchet. Instead being driven extinct, could then survive practically indefinitely, although lower than without random drift.