Haplodiploidy

Haplodiploidy is a sex determination system, also called arrhenotoky, in which males develop from unfertilized eggs and are haploid while females develop from fertilized eggs and are diploid. It determines sex in every member of the insect orders Hymenoptera (bees, ants, wasps, and sawflies) and Thysanoptera (thrips), and appears occasionally in spider mites, some Hemiptera, some beetles, and rotifers. Because an individual sex depends on how many chromosome sets it received, the system produces unusual genealogies: a male has no father and cannot have sons, yet can have grandsons. In a eusocial colony founded by a single queen mated only once, the diploid female workers share about three quarters of their genes on average, a higher relatedness than ordinary sexual reproduction produces, which is why haplodiploidy has featured heavily, if still contentiously, in kin selection theories of how eusociality evolved. The system also purges harmful recessive alleles unusually fast, since any such allele is automatically expressed in haploid males. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/