  We study the genetic behaviour of a population formed by haploid individuals
which reproduce asexually. The genetic information for each individual is
stored along a bit-string (or chromosome) with L bits, where 0-bits represent
the wild-type allele and 1-bits correspond to harmful mutations. Each newborn
inherits this chromosome from its parent with some few random mutations: on
average a fixed number m of bits are flipped. Selection is implemented
according to the number N of 1-bits counted along the individual's chromosome:
the smaller N the higher the probability an individual has to survive a new
time step. Such a population evolves, with births and deaths, and its genetic
distribution becomes stabilised after many enough generations have passed.
  The question we pose concerns the procedure of increasing L. The aim is to
get the same distribution of relative genetic loads N/L among the equilibrated
population, in spite of a larger L. Should we keep the same mutation rate m/L
for different values of L? The answer is yes, which intuitively seems to be
plausible. However, this conclusion is not trivial, according to our
simulational results: the question involves also the population size.
