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Information about Haplodiploidy

The Haplodiploid sex-determination system determines the sex of the offspring of many Hymenopterans (bees, ants, and wasps), and coleopterans (bark beetles). It may help to explain the evolution of eusociality in these species.

Several models have been proposed for the genetic mechanisms of haplodiploid sex-determination. The model most commonly referred to is the complementary allele model. According to this model, if an individual is heterozygous for a certain allele, it develops into a female, whereas hemizygous and homozygous individuals develop into males. In other words, diploid offspring develop from fertilized eggs, and are normally female, while haploid offspring develop into males from unfertilized eggs. Diploid males are infertile, as their sperm do not undergo meiosis which means that their offspring would be triploid. This also means that Hymenopterans may be especially sensitive to inbreeding: Inbreeding reduces the number of different sex alleles present in a population, hence increasing the occurrence of diploid males.

After mating, fertile Hymenopteran females store the sperm in an internal sac called the spermatheca. The mated female controls the release of stored sperm from within the organ: If she releases sperm as an egg passes down the oviduct, the egg is fertilized. [1] Social bees, wasps, and ants can modify sex ratios within colonies to maximize relatedness among members, and to generate a workforce appropriate to surrounding conditions. [2]

Sex-determination in honey bees

In honeybees the drones (males) are entirely derived from the queen, their mother. The queen has 32 chromosomes and the drones have 16 chromosomes. Drones produce genetically identical sperm. Males do not contribute to males - therefore males have no fathers or sons. The genetic makeup of the female worker bees is half derived from the mother, and half from the father. [3] Thus, if a queen bee mates with only one drone, any two of her daughters will share, on average, 3/4 of their genes. The diploid queen's genome is recombined for her daughters, but the haploid father's genome is inherited by his daughters "as is".

While workers can lay unfertilized eggs that become their sons, haplodiploid sex-determination system is beneficial to the individual due to indirect selection. The worker is more related to the queen's daughters (her sisters) than to the workers' sons (her nephews). Helping the queen's offspring to survive is aiding the spread of the same genes that the worker possesses [4] Batches of worker bees are short lived and are constantly being replaced by the next batch, so this kin selection is possibly a strategy to ensure the proper working of the hive. However, since queens usually mate with a dozen drones or more, not all workers are full sisters. Due to the separate storage of drone sperm, a specific batch of brood may be closer related than a specific batch of brood laid at a later date. Kin selection may explain the evolution of these eusocial colonies.

Shared gene proportions in haplo-diploid sex-determination system relationships
Sex Daughter Son Mother Father Full Sister Full Brother Niece/Nephew
Female 1/21/21/21/23/41/43/8
Male 10101/21/21/4

References

1. ^ van Wilgenburg, Ellen; Driessen, Gerard & Beukeboom, Leo W. Single locus complementary sex determination in Hymenoptera: an "unintelligent" design? Frontiers in Zoology 2006, 3:1
2. ^ Mahowald, Michael; von Wettberg, Eric Sex determination in the Hymenoptera Swarthmore College (1999)
3. ^ Sinervo, Barry Kin Selection and Haplodiploidy in Social Hymenoptera 1997
4. ^ Foster, Kevin R.; Ratnieks, Francis L. W. The Effect of Sex-Allocation Biasing on the Evolution of Worker Policing in Hymenopteran Societies The American Naturalist, volume 158 (2001), pages 615–623

See also

Hymenoptera
Linnaeus, 1758

Suborders

Apocrita
Symphyta

Hymenoptera is one of the larger orders of insects, comprising the sawflies, wasps, bees, and ants.
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BEE may refer to:
  • Black Economic Empowerment, the policy of post-apartheid affirmative action in South Africa
  • Biblical Education by Extension, a Christian program designed to instruct theology in countries with weak theological infrastructure.

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Formicidae
Latreille, 1809

Subfamilies
  • Aenictogitoninae
  • Agroecomyrmecinae
  • Amblyoponinae (incl. "Apomyrminae")
  • Aneuretinae
  • Cerapachyinae
  • Dolichoderinae
  • Ecitoninae (incl.

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wasp is any insect of the order Hymenoptera and suborder Apocrita that is not a bee or ant. The suborder Symphyta includes the sawflies and wood wasps, which differ from members of Apocrita by having a broader connection between the mesosoma and metasoma.
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Scolytinae
Latreille, 1807

Genera

See text.

A bark beetle is one of approximately 220 genera with 6,000 species of beetles in the subfamily Scolytinae
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Eusociality is the phenomenon of reproductive specialization found in some animals. It generally involves the production of sterile members of the species, which carry out specialized tasks, effectively caring for the reproductive members.
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Zygosity refers to the genetic condition of a zygote. In genetics, zygosity describes the similarity or dissimilarity of DNA between homologous chromosomes at a specific allelic position or gene.

Every gene in a diploid organism has two alleles at the gene's locus.
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Zygosity refers to the genetic condition of a zygote. In genetics, zygosity describes the similarity or dissimilarity of DNA between homologous chromosomes at a specific allelic position or gene.

Every gene in a diploid organism has two alleles at the gene's locus.
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meiosis (IPA: /maɪˈəʊsɪs/) is the process by which one diploid eukaryotic cell divides to generate four haploid cells often called gametes.
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Polyploidy is the condition of some biological cells and organisms manifested by the presence of more than two homologous sets of chromosomes. Polyploid types are termed according to the number of chromosome sets in the nucleus: triploid (three sets; 3x),
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mating is the pairing of opposite-sex or hermaphroditic internal fertilization animals for copulation and, in social animals, also to raise their offspring. Mating methods include random mating, disassortative mating, assortative mating, or a mating pool.
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sperm is derived from the word spermos (meaning "seed") and refers to the male reproductive cells. Sperm cells are the smaller gametes involved in fertilization.
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The spermatheca is an organ of the female reproductive tract in insects, some molluscs, and certain other invertebrates. Its purpose is to receive and store sperm from the male, and it is usually the site of fertilization when the oocytes are ready.
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oviduct. The eggs travel along the oviduct. The oviduct in birds is divided in several parts:
  • Infundibulum (formation of Chalazae, place of fertilisation)
  • Magnum (formation of egg white)
  • Isthmus

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The factual accuracy of part of this article is disputed.
The dispute is about whether the species/subspecies treatment of Engel (1999) has been accepted by the scientific community.

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Drones are male honey bees. Male honey bees develop when the queen bee lays unfertilized eggs.

Drone genetics

See also:

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queen bee is typically used to refer to an adult, mated female in a honey bee colony or hive; she is usually the mother of all the bees in the hive. The queens are developed from larvae selected by worker bees and specially fed in order to become sexually mature.
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sperm is derived from the word spermos (meaning "seed") and refers to the male reproductive cells. Sperm cells are the smaller gametes involved in fertilization.
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Chromosomal crossover (or crossing over) is the process by which two chromosomes, paired up during prophase 1 of meiosis, exchange some portion of their DNA. Crossing over is specifically initiated in pachytene, before the synaptonemal complex develops, and is not completed
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kin selection.

The concept was formalized by JBS Haldane (1955)[1] and W. D. Hamilton (1963)[2], while the actual term "kin selection" may first have been coined by John Maynard Smith (1964)[3]
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Swarthmore College is a private, independent, liberal arts college in the United States with an enrollment of about 1,500 students. The college is located in the borough of Swarthmore, Pennsylvania, 11 miles (17.7 km) southwest of Philadelphia.
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American Naturalist is a monthly scientific journal, founded in 1867 and associated with the American Society of Naturalists. It is published by the University of Chicago Press. The journal covers ecology, evolutionary biology, population, and integrative biology research.
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Genetics (not to be confused with the UK publication, Journal of Genetics). is a monthly scientific journal publishing investigations bearing on heredity and variation. Genetics is published by the Genetics Society of America.
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Ploidy is the number of homologous sets of chromosomes in a biological cell. The ploidy of cells can vary within an organism. In humans, most cells are diploid (containing one set of chromosomes from each parent), but sex cells (sperm and egg) are haploid.
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The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals (the other is the Y chromosome). It is a part of the XY sex-determination system and X0 sex-determination system.
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The Y chromosome is the sex-determining chromosome in humans and most other mammals. In mammals, it contains the gene SRY, which triggers testis development, thus determining sex.

Overview

Most mammals have one pair of sex chromosomes in each cell.
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Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division.]] A chromosome is a single large macromolecule of DNA, and constitutes a physically organized form of DNA in a cell.
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Sexual differentiation is the process of development of the differences between males and females from an undifferentiated zygote (fertilized egg). As male and female individuals develop from zygotes into fetuses, into infants, children, adolescents, and eventually into adults, sex
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A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most sexual organisms have two sexes. In many cases, sex determination is genetic: males and females have different alleles or even different genes that
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The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects (Drosophila) and some plants (Ginkgo). In the XY sex-determination system, females have two of the same kind of sex chromosome (XX), and are called
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