Dwarfism

from Wikipedia, the free encyclopedia

Dwarfing , also known as nanism or nanosomy , is a general evolutionary phenomenon of the adaptation of species to certain environmental conditions . This leads to a miniaturization and sometimes a reduction in organs . The cause is a reduction in the size of the living space and a restriction in the food supply, which is not only expressed in a temporary, phenotypic adaptation, but is also genotypically anchored through selection pressure . The prerequisite for this is the isolation of the habitat, which leads to the development of dwarfed subspecies and species over long periods of time . The phenomenon was particularly observed in connection with the reduced living space and limited food supply on islands ( island dwarfing ).

The dwarfing has been studied especially for the lineages of vertebrates , where it can be seen in the reduction of the skeletal elements e.g. B. is particularly noticeable in the extinct dwarf elephants . Often smaller species can also be found in bony fish , including the second smallest recent vertebrate ( Paedocypris progenetica ) ( dwarfism in bony fish ), which was long thought to be the smallest recent vertebrate until the even smaller frog species Paedophryne amauensis was discovered in 2009 .

In addition to evolutionary dwarfism or short stature, there are numerous deficit-related forms of short stature in the plant and animal kingdoms as well as in humans that occur during the ontogenesis of an individual: dwarfism as a result of genetic defects, dwarfism as a result of deficiencies or malnutrition, dwarfism as a result of hormonal disorders.

Individual evidence

  1. ^ Island dwarfing: Mammoths lived on Crete in miniature format. In: Spiegel Online . May 9, 2012, accessed June 10, 2018 .
  2. ↑ Lexicon of Biology, article "dwarfism"

See also

literature

Web links

Wiktionary: Nanism  - explanations of meanings, word origins, synonyms, translations