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A sheep–goat hybrid (called a geep in popular media or sometimes a shoat) is a domestic hybrid between a
sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...
and a
goat The goat or domestic goat (''Capra hircus'') is a species of Caprinae, goat-antelope that is mostly kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the ...
. While sheep and goats are similar and can be mated, they belong to different genera in the subfamily
Caprinae The subfamily Caprinae, also sometimes referred to as the tribe Caprini, is part of the ruminant family Bovidae, and consists of mostly medium-sized bovids. A member of this subfamily is called a caprine. Prominent members include sheep and g ...
of the family
Bovid The Bovidae comprise the family (biology), biological family of cloven-hoofed, ruminant mammals that includes Bos, cattle, bison, Bubalina, buffalo, antelopes (including Caprinae, goat-antelopes), Ovis, sheep and Capra (genus), goats. A member o ...
ae. Sheep belong to the genus ''
Ovis ''Ovis'' is a genus of mammals, part of the Caprinae subfamily of the ruminant family (biology), family Bovidae. Its seven highly sociable species are known as sheep or ovines. Domestic sheep are members of the genus, and are thought to be des ...
'' and have 54
chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...
s, while goats belong to the genus '' Capra'' and have 60 chromosomes. The offspring of a sheep–goat pairing is generally stillborn. Despite widespread shared pasturing of goats and sheep, hybrids are very rare, demonstrating the genetic distance between the two species. They are not to be confused with sheep–goat chimera, which are artificially created by combining the embryos of a goat and a sheep.


Characteristics

There is a long-standing belief in sheep–goat hybrids, which is presumably due to the animals' resemblance to each other. Some primitive varieties of sheep may be misidentified as goats. In ''Darwinism – An Exposition of the Theory of Natural Selection with Some of Its Applications'' (1889),
Alfred Russel Wallace Alfred Russel Wallace (8 January 1823 – 7 November 1913) was an English naturalist, explorer, geographer, anthropologist, biologist and illustrator. He independently conceived the theory of evolution through natural selection; his 1858 pap ...
wrote:
..the following statement of Mr. Low: "It has been long known to shepherds, though questioned by naturalists, that the progeny of the cross between the sheep and goat is fertile. Breeds of this mixed race are numerous in the north of Europe." Nothing appears to be known of such hybrids either in Scandinavia or in Italy; but Professor Giglioli of Florence has kindly given me some useful references to works in which they are described. The following extract from his letter is very interesting: "I need not tell you that there being such hybrids is now generally accepted as a fact. Buffon (''Supplements'', tom. iii. p. 7, 1756) obtained one such hybrid in 1751 and eight in 1752. Sanson (''La Culture'', vol. vi. p. 372, 1865) mentions a case observed in the Vosges, France. Geoff. St. Hilaire (''Hist. Nat. Gén. des reg. org.'', vol. iii. p. 163) was the first to mention, I believe, that in different parts of South America the ram is more usually crossed with the she-goat than the sheep with the he-goat. The well-known 'pellones' of Chile are produced by the second and third generation of such hybrids (Gay, 'Hist, de Chile,' vol. i. p. 466, ''Agriculture'', 1862). Hybrids bred from goat and sheep are called 'chabin' in French, and 'cabruno' in Spanish. In Chile such hybrids are called 'carneros lanudos'; their breeding ''inter se'' appears to be not always successful, and often the original cross has to be recommenced to obtain the proportion of three-eighths of he-goat and five-eighths of sheep, or of three-eighths of ram and five-eighths of she-goat; such being the reputed best hybrids."
Supposedly, most sheep–goat hybrids die as
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 ...
s. Hybrid male
mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...
are often sterile, demonstrating a phenomenon known as Haldane's rule. The Haldane phenomenon may apply even when the parent species have the same number of chromosomes, as in most cat-species hybrids. It sometimes does not apply when the species chromosome number is different, as in
wild horse The wild horse (''Equus ferus'') is a species of the genus Equus (genus), ''Equus'', which includes as subspecies the modern domestication of the horse, domesticated horse (''Equus ferus caballus'') as well as the Endangered species, endangered ...
(chromosome number = 66) with
domestic horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million ...
(chromosome number = 64) hybrids. Hybrid female fertility tends to decrease with increasing divergence in chromosome similarity between parent species. Presumably, this is due to mismatch problems during
meiosis Meiosis () is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, the sperm or egg cells. It involves two rounds of division that ultimately result in four cells, each with only one c ...
and the resulting production of
egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...
s with unbalanced genetic complements. However, a buck–ewe hybrid born in 2014 died of pregnancy related complications in 2018 raising the question if the parent–species combination has an influence on hybrid fertility. Blood transcriptome analysis of a buck–ewe hybrid and its parents revealed significant deviations from previously described imprinting schemes and a higher contribution from the goat genome to the genes expressed in the hybrid's blood. Due to the common genome, buck–ewe hybrid share 870 common genes with the maternal goat and 368 genes with the paternal sheep.


Alleged and confirmed cases

At the
Botswana Botswana, officially the Republic of Botswana, is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory part of the Kalahari Desert. It is bordered by South Africa to the sou ...
Ministry of Agriculture in 2000, a male sheep impregnated a female goat resulting in a live male offspring. This hybrid had 57
chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...
s, intermediate between sheep (54) and goats (60) and was intermediate between the two parent species in type. It had a coarse outer coat, a woolly inner coat, long goat-like legs and a heavy sheep-like body. Although infertile, the hybrid had a very active libido, mounting both ewes and does even when they were not in heat. He was castrated when he was 10 months old, as were the other kids and lambs in the herd. A male sheep impregnated a female goat in
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
resulting in a mixed litter of kids and a female sheep–goat hybrid with 57 chromosomes. The hybrid was subsequently shown to be fertile when mated with a ram. In
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
, natural mating of a doe with a ram produced a female hybrid carrying 57 chromosomes. This animal backcrossed in the veterinary college of
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to a ram delivered a stillborn and a living male offspring with 54 chromosomes. In March 2014, a buck–ewe hybrid was born on a farm close to Göttingen in Germany. Also in March 2014, a male buck–ewe hybrid was born in Ireland. There was a reported case of live births of twin geep on a farm in Ireland in 2018. There was reported case of a live birth of a sheep–goat hybrid on a farm in
Tábor Tábor (; ) is a town in the South Bohemian Region of the Czech Republic. It has about 34,000 inhabitants, making it the second most populated town in the region. The town was founded by the Hussites in 1420. The historic town centre is well pres ...
in
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
in 2020. Her name was Barunka and she had health complications after being born. Her owners did not know if she was a goat or sheep, since neither goats nor sheep accepted her. Upon further inspection, it was discovered she was a sheep–goat hybrid. In May 2021, a healthy doe–ram hybrid was born on a farm in Kentucky, USA despite complications during labor. Her status as a hybrid was confirmed by
genetic testing Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...
: she has a hybrid karyotype of 57, XX.


Sheep–goat chimera


History

A sheep–goat chimera (sometimes called a geep in popular media) is a
chimera Chimera, Chimaera, or Chimaira (Greek for " she-goat") originally referred to: * Chimera (mythology), a fire-breathing monster of ancient Lycia said to combine parts from multiple animals * Mount Chimaera, a fire-spewing region of Lycia or Cilicia ...
produced by combining the
embryos 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 spe ...
of a
goat The goat or domestic goat (''Capra hircus'') is a species of Caprinae, goat-antelope that is mostly kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the ...
and a
sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...
; the resulting
animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...
has cells of both sheep and goat origin. A sheep–goat chimera should not be confused with a sheep–goat hybrid, which can result when a goat mates with a sheep. The first sheepgoat chimeras were created by researchers at the Institute of Animal Physiology in
Cambridge Cambridge ( ) is a List of cities in the United Kingdom, city and non-metropolitan district in the county of Cambridgeshire, England. It is the county town of Cambridgeshire and is located on the River Cam, north of London. As of the 2021 Unit ...
,
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
by combining sheep embryos with goat embryos. They reported their results in 1984. The successful chimeras were a
mosaic A mosaic () is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/Mortar (masonry), mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and ...
of goat and sheep cells and tissues.


Characteristics

In a chimera, each set of cells (germ line) keeps its own species' identity instead of being intermediate in type between the parental species. Because the chimera contains cells from (at least) two genetically different embryos, and each of these arose by fertilization of an egg by a sperm cell, it has (at least) ''four'' genetic parents. In contrast, a hybrid has only two. Although the individual cells in interspecies chimeras are entirely of one of the component species, their behaviour is influenced by the environment in which they find themselves. The sheep–goat chimeras have yielded several demonstrations of this. The most obvious was that the woolly areas of their fleece, tufts of goat wool ( angora-type) grew intermingled with ordinary sheep wool, even though the goat breed used in the experiments did not exhibit any wool whatsoever. Sheepgoat chimeras as a general rule may be assumed to be
fertile Fertility in colloquial terms refers the ability to have offspring. In demographic contexts, fertility refers to the actual production of offspring, rather than the physical capability to reproduce, which is termed fecundity. The fertility rate is ...
, with the reservations that apply to chimeras generally (which again reflect that the parent embryos may have been of different sex, so that the animal, apart from being a chimera, may also be intersex). But in accordance with the mosaic- (as opposed to hybrid-) nature of the interspecies chimera, any individual sperm or egg cell it produces must be of either the pure sheep or the pure goat variety. Whether in fact viable germ cells of both species may be, or have been, produced within the same individual is unknown. The term ''shoat'' is sometimes used for sheepgoat hybrids and chimeras, but that term more conventionally means a young piglet.


References


Notes


External links


Farmersjournal.ie
{{DEFAULTSORT:Sheep-goat hybrid Bovid hybrids Sheep Goats Intergeneric hybrids