The speed of Muller's ratchet in small (200 individuals) asexual and hybridogenetic populations. The vertical axis shows the number of lost classes respectively the number of fixed mutations. Both graphs show the average of 10 runs per reproductive mode. U was set to 0.3 for both reproductive modes and α = 1 for hybridogenetic reproduction to allow a comparison between asexual and hybridogenetic reproduction. Thicker lines indicate the losses of mutation classes whereas thinner lines indicate the number of fixed mutations in the population.