 Mutations without recessive lethal (or sterile) phenotype in diploid organisms can simply be bred to homozygosity and maintained  by crossing homozygotes.
<clarity>  Mutations without recessive lethal (or sterile) phenotype in diploid organisms can simply be bred to homozygosity and maintained  by crossing homozygotes.
 Mutations without recessive lethal (or sterile) phenotypes can simply be bred to homozygosity and maintained by crossing homozygotes.