Summary
Males are haploid and females diploid in Hymenoptera, shaping relatedness and sociality.
In depth
Fertilised eggs become diploid females and unfertilised ones become haploid males. Sisters share 75 percent of genes, more than they would with their own offspring (50 percent), favouring cooperation in Hymenoptera. Termites are diploid but also eusocial, so this is not the only explanation.
It increases relatedness among sisters. Not all haplodiploid species are social. Alternative explanations include ecological factors.
Key idea: genetic relatedness may promote cooperation.
Haplodiploidy occurs in Hymenoptera (ants, bees, wasps), thrips and some beetles and mites. Queens can control the sex of eggs by storing sperm and releasing it or not. Haploid males produce sperm by mitosis. Sisters share 75 percent of genes with each other and 50 percent with their offspring, so helping a mother raise sisters could yield more inclusive fitness (the 3/4 relatedness hypothesis), but males, which are less related to sisters (25 percent), complicate matters, and many eusocial groups, such as termites, are diploid.
Haplodiploidy exposes harmful recessive alleles in males, purging them, and may reduce inbreeding costs. Sex ratio conflicts arise between queens and workers: workers prefer a 3:1 female to male investment ratio, queens 1:1.
Key idea: the 75 percent figure applies only to full sisters with a singly mated queen, and polyandry lowers it.
Frequently asked questions
What is Insect Haplodiploidy?
Males are haploid and females diploid in Hymenoptera, shaping relatedness and sociality.
Which area of biology covers Insect Haplodiploidy, and how advanced is it?
Insect Haplodiploidy is one of the 53 topics in Zoology & Animal Diversity. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Eusociality, Parental Care Evolution, Parasitism in Animals.
Can you give an example of Insect Haplodiploidy?
A queen controls the sex of offspring by fertilising or not.
What should I learn before Insect Haplodiploidy?
Work through the Beginner topics in Zoology & Animal Diversity first, such as Animal Kingdom, Vertebrates and Invertebrates, Sponges, then return to Insect Haplodiploidy. Advanced topics assume the Intermediate vocabulary.
What topics are related to Insect Haplodiploidy?
The closest topics to Insect Haplodiploidy are Eusociality, Parental Care Evolution, Parasitism in Animals, Bioluminescence. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Insect Haplodiploidy?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Insect Haplodiploidy. To practise the whole of Zoology & Animal Diversity, use the Zoology & Animal Diversity quiz.
How is Insect Haplodiploidy different from Eusociality?
Insect Haplodiploidy: Males are haploid and females diploid in Hymenoptera, shaping relatedness and sociality. Eusociality: Social organisation with reproductive division of labour, overlapping generations and cooperative care, as in ants and bees. Read both side by side and note what each one explains.
How should I study Insect Haplodiploidy step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Eusociality and explain the difference aloud. Finally, take the Zoology & Animal Diversity quiz and come back to this page for any question you miss.