The gene pool of the wild camels, because of their isolation and lack of interbreeding with domestic Bactrian camels, has much greater diversity and a wider range of adaptability and capacity for random mutations. This gene pool contains rich source materials for a number of scientific studies.
That confirms what conservationists have long suspected: that the two groups are genetically unique, and must be considered to be distinct subspecies.
The Bactrian camel is thought to have been domesticated (independent of the dromedary) sometime before 2500 BCE, in Northeast Afghanistan, or southwestern Turkestan. The dromedary camel is believed to have been domesticated between 4000 BCE and 2000 BCE in Arabia. As pack animals, these ungulates are virtually unsurpassed, able to carry 170–250 kg (370–550 lb) at a rate of 47 km (30 miles) per day, or 4 km/h (2 mph) over a period of four days.
In 2008 the wild camel was designated a NEW and SEPARATE species by scientists at the Institute of Population Genetics, University of Veterinary Medicine, Vienna. The scientists have published a paper (Genetic status of wild camels ‘Camelus ferus’ in Mongolia) which concludes:
Another difference is the ability of these wild camels to drink saltwater slush, although whether the camel can extract useful water from it is not yet certain. Domesticated camels are unable to drink such salty water.
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The wild camels have smaller, more slender bodies with thinner, more lithe legs, and lower pyramid-shaped humps.
Their habitat is in arid plains and hills where water sources are scarce and very little vegetation exists with shrubs as their main food source.
We identified 1,986,420 heterozygous single nucleotide polymorphisms (SNPs) in the wild camel genome and 2,129,442 heterozygous SNPs in the domestic camel genome (Supplementary Table S8). In both cases, the heterozygosity rates are estimated to be about 1.0 × 10−3 across the whole genomes (Fig. 2a). The number of small indels identified in the two genomes is also comparable (Supplementary Table S9).
Fewer than 1000 wild Bactrian camels survive in just a few areas in north-west China and south-west Mongolia.
Frankfurt Zoo, Germany Image credit: Elinor D via Wikimedia Commons, some rights reserved
The 500-bp paired-end and 3-kb mate-pair DNA library were sequenced on the Illumina Genome Analyzer IIx system. The 10-kb mate-pair DNA library was sequenced on the Applied Biosystems SOLiD 3 system. The 20-kb mate-pair DNA library was sequenced using the Roche Genome Sequencer FLX system. Library preparation, sequencing and base calling were performed according to the manufacturer’s recommendations.
The researchers cannot be sure, but they suspect that changes to the climate may have caused one group of Bactrian camels to migrate en masse away from the others, and that the ancestor of the domestic two-humped camel probably went extinct thousands of years ago.
However, domestic camels did not originate from the group of camels that still survive in the wild, say the researchers.
In this study, we sequenced the genomes of both wild and domestic bactrian camel, to better understand the history of their evolution and domestication, and to provide a resource for research into the genetic mechanisms that enable camels to survive extreme environments.
Compared to the domesticated Bactrian camel, the wild Bactrian camel is slightly smaller and has been described as "relatively small, lithe, and slender-legged, with very narrow feet and a body that looks laterally compressed."
H. Meng, Room 3‐319, Agriculture Building, Shanghai Jiao Tong University, Dongchuan Road 800, Minhang District, 200240 Shanghai, China. E‐mail: email@example.com S. Hu, Beijing Institute of Genomics, Chinese Academy of Sciences, No. 7 Beitucheng West Road, Chaoyang, 100029 Beijing, China. E‐mail: firstname.lastname@example.org
Accession codes: This Whole Genome Shotgun project has been deposited in DDBJ/EMBL/GenBank as project accession http://www.ncbi.nlm.nih.gov/bioproject/?term=PRJNA76177. The genome assembly has been deposited in DDBJ/EMBL/GenBank under the accession code http://www.ncbi.nlm.nih.gov/nuccore/?term=AGVR00000000. The version described in this paper is the first version, AGVR01000000.
Normal distribution and points of introduction of domestic camels (Wilson, 1998). Click map to enlarge.
Zoological opinion nowadays tends to favour the idea that C. bactrianus and C. dromedarius are descendants of two different subspecies of C. ferus (Peters and von den Driesch 1997: 652) and there is no evidence to suggest that the original range of C. ferus included those parts of Central Asia and Iran where some of the earliest Bactrian remains have been found.
In particular, a population of wild Bactrian camel has been discovered to live within a part of the Gashun Gobi region of the Gobi Desert. This population is distinct from domesticated herds both in genetic makeup and in behavior.
"The wild Bactrian camel differs from the domestic Bactrian in a number of ways – smaller, more conical humps, flatter skull (havtagai, the Mongolian name for a wild Bactrian camel, means 'flat-head'), a different shape of foot – but the outstanding difference is genetic."
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It can also survive on water even saltier than seawater – which no other large mammal in the world, including the domestic Bactrian camel, can tolerate.
Bactrians are the last remaining wild camels of any type.
Domestic Bactrian Camel
The animal is listed as critically endangered and the Zoological Society of London's EDGE of Existence programme ranks them among the 100 most evolutionarily distinct but globally endangered animals.
Bactrian camels are induced ovulators - they ovulate after insemination of semen into the vagina; the seminal plasma, not the spermatozoa, induces ovulation. Ovulation occurs in 87% of females after insemination: 66% ovulate within 36 h and the rest by 48 h (the same as natural mating). The least amount of semen required to elicit ovulation is about 1.0 ml.
Re‐use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.
An analysis by scientists in China and Inner Mongolia shows that wild Bactrian camels are distantly related to their domestic two-humped counterparts.
How to cite this article: Jirimutu. et al. Genome sequences of wild and domestic bactrian camels. Nat. Commun. 3:1202 doi: 10.1038/ncomms2192 (2012).
Bactrian camels (Camelus bactrianus) are huge animals that stand up to 2.3m tall at the shoulder and can weigh up to 690kg.
Recent research has also shown that the two find it difficult to interbreed.
The domesticated Bactrian camel has served as a pack animal in inner Asia since ancient times. With its tolerance for cold, drought, and high altitudes, it enabled the travel of caravans on the Silk Road. A small number of feral Bactrian camels still roam the Mangystau Province of southwest Kazakhstan and the Kashmir Valley in India. Feral herds of Bactrian camels can be found in Australia and during the late 19th century a few existed in the southwest deserts of the United States.
The only extant predators that regularly target wild Bactrian camels are gray wolves, which have been seen to pursue weaker and weather-battered camels as they try to reach oases. Due to increasingly dry conditions in the species' range, the numbers of cases of wolf predation on wild camels at oases has reportedly increased. Historically, the Caspian tiger was also known to prey on wild Bactrian camels, but this subspecies is almost certainly extinct.
"The wild group is worthy of conservation as a separate entity," says Richard Kock, conservation programme manager for the Zoological Society of London.
As many as three regions in the genetic makeup are distinctly different from Bactrian camels, with up to a 3% difference in the base genetic code. However, with so few wild camels, what the natural genetic diversity within a population would have been is not clear.
Bactrian camels in the Chuya Steppe, Altai Mountains, Russia
Bactrian camels belong to a fairly small group of animals that regularly eat snow to provide their water needs. Any animals living above the snowline are obliged to do this, as snow and ice are the only forms of water during winter, and by doing so, their range is greatly enlarged. The latent heat of snow and ice is enormous compared with the heat capacity of water, demanding a large sacrifice in heat energy and forcing animals to eat only small amounts at a time.
To find out more about this relationship, Rimutu Ji of the Inner Mongolia Agricultural University in Huhhot, China, and He Meng of Shanghai Jiao Tong University, teamed up with scientists from the Chinese Academy of Sciences to sample the DNA of 18 domestic and three wild camels selected from different regions.
They also confirmed that all domestic camels originated from the same population.