Creeper chickens are characterised by abnormally short legs, so short that the body is carried a few centimetres from the ground. This chondrodystrophy (dwarfism) is caused by a dominant lethal allele, ''Cp''. A number of breeds display the characteristic, among them the

Chabo The Japanese Bantam or Chabo () is a Japanese breed of ornamental chicken. It is a true bantam breed, meaning that it has no large fowl counterpart. It characterised by very short legs – the result of hereditary chondrodystrophy – and a larg ...

and Jitokku breeds of Japan, the Courte-pattes of France, the

Krüper The Krüper () is a German breed of creeper chicken. It originates in the former Duchy of Berg, now the Bergisches Land in western Germany, and is one of three chicken breeds from that area, the others being the Bergische Kräher and the Bergi ...

of Germany, the Luttehøns of Denmark, and the Scots Dumpy. They have been called by many names, among them bakies, brevicrews, corlaighs, crawlers, creepers, creepies, dumpfries, dumpies and jumpers.

History

Creeper chickens have been known and described since

Renaissance The Renaissance ( , ) is a Periodization, period of history and a European cultural movement covering the 15th and 16th centuries. It marked the transition from the Middle Ages to modernity and was characterized by an effort to revive and sur ...

times at least. Chickens of this type were described and illustrated in the ''Monstrorum Historia'' of the Bolognese naturalist

Ulisse Aldrovandi Ulisse Aldrovandi (11 September 1522 – 4 May 1605) was an Italian naturalist, the moving force behind Bologna's botanical garden, one of the first in Europe. Carl Linnaeus and the comte de Buffon reckoned him the father of natural history stud ...

(1522–1605), published posthumously in 1642 with text by Bartolomeo Ambrosini. In his ''

The Variation of Animals and Plants Under Domestication ''The Variation of Animals and Plants Under Domestication'' is a book by Charles Darwin that was first published in January 1868. A large proportion of the book contains detailed information on the domestication of animals and plants but it al ...

'' of 1868,

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...

writes that creeper chickens were among the types described in a Chinese encyclopaedia compiled from earlier sources and published in 1596. They have been called by many names, among them bakies, brevicrews, corlaighs, crawlers, creepers, creepies, dumpfries, dumpies and jumpers. The creeper gene was described by

Ira Eugene Cutler Ira or IRA may refer to: *Ira (name), a Hebrew, Sanskrit, Russian or Finnish language personal name * Ira (surname), a rare Estonian family name; occurs in some other languages *Iran, UNDP code IRA Law and finance * Indian Reorganization Act of 1 ...

in 1925, and confirmed by Walter Landauer and L.C. Dunn in 1930. The symbol ''Cp'' was assigned to it by Frederick Hutt in 1933. It was shown to be present in the

by Landauer in 1942, in the Jitokko by S. Okamoto in the same year, and in the Gan-Dori and Miyaji-Dori by Tohru Shibuya in 1972.

Biology

The short legs of creeper chickens are the result of

autosomal dominant In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the Phenotype, effect of a different variant of the same gene on Homologous chromosome, the other copy of the chromosome. The firs ...

transmission of a

lethal allele Lethal alleles (also referred to as lethal or lethals) are alleles that cause the death of the organism that carries them. They are usually a result of mutations in genes that are essential for growth or development. Lethal alleles can be recessive ...

, ''Cp''. Affected birds are

heterozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mos ...

(''Cp''/+) for the gene;

homozygotes Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mos ...

(''Cp''/''Cp'') die at the

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

stage. The ''Cp'' trait is linked closely to the gene for the rose comb, ''MNR2''. Shortening of the leg bones is also observed in Indian Game, and some birds carry a lethal allele. It is quite different to that of the creeper; Hutt assigned it the symbol ''Cl''.

References

Aviculture Animal genes {{bots, deny=Citation bot