Haplodiploidy
As haplodiploidy refers to a form of Geschlechtsdetermination in which a sex only one set of chromosomes carrying ( haploid ) and the opposite sex of the double set of chromosomes ( diploid ). Usually the male sex is haploid.
One can differentiate between two basic types of haplodiploidy depending on the origin:
- Arrhenotocia - haploid individuals arise through parthenogenesis , i.e. from an unfertilized egg cell
- Pseudoarrhenotokia - haploid individuals due to subsequent loss of the paternal genome
In over 2000 species of hymenoptera ( ants , bees , wasps, etc.), males hatch from unfertilized eggs and are therefore haploid . Haplodiploidy is also found in some bark beetles ( tribe Xyloborini and kinship circle of the genus Coccotrypes in the tribe Dryocoetini ), many thrips , some scale insects , mites and nematode group Oxyuroidea .
Since the genome of the males can also be found in the mother and in the female siblings and is thus extremely related, it is assumed that haplodiploidy favors the formation of states . On the other hand, sex determination in termites does not take place haplodiploid, nevertheless highly developed forms of social organization have developed in all species of this hemimetabolic insect order.
In the case of the well-examined bees, it has been found that, similar to humans, a certain gene is ultimately decisive for determining sex. If it is available in two different versions (in the case of the fertilized eggs), females arise. If there is only one version (in the case of unfertilized eggs), males result. By inbreeding can to come that this gene is present in fertilized eggs in two identical versions. Then diploid males emerge. However, their larvae are eaten by the workers after they hatch from the egg.
literature
R. Gadagkar: On testing the role of genetic asymmetries created by haplodiploidy in the evolution of eusociality in the Hymenoptera In: Journal of Genetics 70 (1), 1991, pp. 1-31 online at IISC
swell
- ↑ a b Panagiota Manolakou, Giagkos Lavranos and Roxani Angelopoulou. Molecular patterns of sex determination in the animal kingdom: a comparative study of the biology of reproduction. 2006. Reproductive Biology and Endocrinology, 4:59. doi : 10.1186 / 1477-7827-4-59
- ↑ BB Normark, BH Jordal, BD Farrell: Origin of a haplodiploid beetle lineage In: Proceedings of the Royal Society B: Biological Sciences 266 (1435), November 22, 1999, pp 2253-2259 online from Royal Society Publishing
- ↑ BJ Crespi: Eusociality in Australian gall thrips in: Nature 359 (6397), 1992, pp 724-726
- ↑ SW Brown: Haplodiploidy in the Diaspididae - confirmation of an evolutionary hypothesis In: Evolution 12 (1), March 1958, pp. 115-116
- ^ RH Cruickshank, RH Thomas: Evolution of haplodiploidy in dermanyssine mites (Acari: Mesostigmata) In: Evolution . 53 (6), December 1999, pp. 1796-1803
- ↑ ML Adamson: Haplodiploidy of Oxyurida. Effects of this phenomenon in the life cycle In: Annales de parasitologie humaine et comparée 59 (4), 1984, pp. 387-413 PMID 6486626
- ↑ KR Foster, T. Wenseleers, FLW Ratnieks: Kin selection is the key to altruism In: Trends in ecology and evolution 21 (2), February 2006, pp. 57-60 PMID 16701471
- ^ Schmidt GH: Social polymorphism in insects - problems of box formation in the animal kingdom. Scientific publishing company Stuttgart 1974.