The evolutionary force of recombination is lacking in asexually repro-
ducing populations. As a consequence, the population can suffer an
irreversible accumulation of deleterious mutations, a phenomenon known
as Muller's ratchet. The three most important parameters of this model
are: the population size, the mutation rate and the selective
disadvantage each mutation adds to a genotype. The long-standing
question on the rate of accumulation of deleterious mutations depending
on these three parameters will not be answered analytically in this
talk, but I will give some evidence for asymptotics of the rate of the
ratchet. This is joint work with Anton Wakolbinger (Frankfurt) and
Alison Etheridge (Oxford).