A type of reproduction in fungi that results in genetic recombination without the formation and fusion of gametes. It occurs in heterokaryotic mycelia, in which two haploid nuclei fuse and then divide by mitosis, during which a form of crossing over occurs. During subsequent divisions chromosomes are progressively lost from the resultant diploid nucleus so that the haploid condition is restored. The asexual spores produced during the cycle will be genetically different from the original parent mycelium as a result of the crossing over that has occurred.