haplodiploidy
n. the state in which individuals of one sex have only one set of chromosomes (i.e., are haploid), because they have developed from an unfertilized egg, and individuals of the other sex have two sets of chromosomes (i.e., are diploid). Haplodiploidy is common in bees and wasps, in which males are haploid. Their female offspring inherit identical paternal genes and thus share 75% of their genes (siblings of diploid parents share only 50% of their genes). This provides a genetic basis for eusociality. —haplodiploid
adj.