Thelytoky (from the Greek thēlys "female" and tokos "birth") is a type of parthenogenesis in which females are produced from unfertilized eggs, as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in about 1,500 species, about 1 in 1000 of described animal species, according to a 1984 study.[1] It is more common in invertebrates, like arthropods, but it can occur in vertebrates, including salamanders, fish, and reptiles such as some whiptail lizards.

Thelytoky can occur by a number of different mechanisms each of which has a different impact on the level of homozygosity. It can be induced in Hymenoptera by the bacteria Wolbachia and Cardinium,[2] and has also been described in several groups of Hymenoptera, including Cynipidae, Tenthredinidae, Aphelinidae, Ichneumonidae, Apidae and Formicidae.[3]

Thelytoky in ants, bees, and wasps

Hymenoptera (ants, bees, and wasps) have a haplodiploid sex-determination system. They produce haploid males from unfertilized eggs through arrhenotokous parthenogenesis. However, in a few social hymenopterans, queens or workers are capable of producing diploid female offspring by thelytoky.[4] The daughters produced may or may not be complete clones of their mother depending on the type of parthenogenesis that takes place.[5][6] The offspring can develop into either queens or workers. Examples of such species include the Cape bee, Apis mellifera capensis, Mycocepurus smithii and clonal raider ant, Cerapachys biroi.

See also


  1. ^ White, Michael J.D. (1984). "Chromosomal Mechanisms in Animal Reproduction" (PDF). Bolletino di zoologia 51 (1-2): 1–23.  
  2. ^ Jeong, G; R Stouthamer (2004-11-03). "Genetics of female functional virginity in the Parthenogenesis-Wolbachia infected parasitoid wasp Telenomus nawai (Hymenoptera: Scelionidae)" (PDF). Heredity 94 (4): 402–407.  
  3. ^ Suomalainen, Esko; Anssi Saura; Juhani Lokki (1987-08-31). Cytology and evolution in parthenogenesis. CRC Press. pp. 29–31, 51.  
  4. ^ Pearcy, M. (2004). "Conditional Use of Sex and Parthenogenesis for Worker and Queen Production in Ants" (PDF). Science 306 (5702): 1780–1783.  
  5. ^ Fournier, Denis; Estoup, Arnaud; Orivel, Jérôme; Foucaud, Julien; Jourdan, Hervé; Breton, Julien Le; Keller, Laurent (2005). "Clonal reproduction by males and females in the little fire ant" (PDF). Nature 435 (7046): 1230–1234.  
  6. ^ Baudry, Emmanuelle; Per Kryger; Mike Allsopp; Nikolaus Koeniger; Dominique Vautrin; Florence Mougel; Jean-Marie Cornuet; Michel Solignac (2004-05-01). "Whole-Genome Scan in Thelytokous-Laying Workers of the Cape Honeybee (Apis mellifera capensis): Central Fusion, Reduced Recombination Rates and Centromere Mapping Using Half-Tetrad Analysis". Genetics 167 (1): 243–252.