Taxonomy and Evolution

Taxonomy

The most agreed upon classification for camelidae is as follows:

Order: Artiodaetyla

Artiodactyla is the order that includes all even-toed, hoofed mammals. The size of animals within this order is very variable. The main constant characteristic is the anatomy of the foot which has an even number of digits (2 in the case of camelidae). The order is represented by 9 recent families: Suidae (pigs), Tayassuidae (i.e colored peccary), Hippopotamidae (hippopo tamuses), Tragulidae (chevrotains, mouse deer), Cervidae (deer), Giraffidae (giraffes), Antilocapridae (i.e. American antelopes, pronghorn antelopes), Bovidae (i.e. elands, buffalos, bison, cattle, sheep, goats, gazelles, oryx, waterbucks...), and Camelidae (dromedaries, Bactrian camels, llamas, alpacas, guanacos and vicuñas).

These mammals exist throughout the world except for Australia and New Zealand, Antartica and isolated islands. Camelidae belong to the sub-order of Tylopoda or padded foot animals.

Family: Camelidae

The camelidae family contains 2 subfamilies (Camelinae and Laminae) divided into 3 recent genera (Camelus, Lama and Vicuña) with a total of 6 species. All these species have 37 pairs of chromosomes (72 autosomes and 2 heterosomes).

Genus: Camelus (2 species)

The genus Camelus includes two different species:

Camelus dromedarius: known also as the single-humped camel. Arabian camel or dromedary.
Camelus bactrianus: known as the double-humped camel or Asian camel.

Genus: Lama (3 species)

The genus llama is confined to the South American continent and includes 3 species:
Lama glama: the llama Lama pacos: the alpaca Lama guanacoe: the Guanaco
Lama pacos: the alpaca
Lama guanacoe: the Guanaco

Genus: Vicugna (one species)

Vicugna vicugna: the vicuña

Evolution of the camelidae.

Fossil discoveries suggest that all camelidae originated from the same ancestor which lived in North America about 40 million years ago. The distinction of laminae from camelinae may have started in the Eocene epoch and been completed in the Pleistocene some 3 to 4 million years ago. Camelinae migrated to Asia across the Bering Strait when it was still a land bridge and formed the Old World camelids (Camelus dromedarius and Camelus bactrianus) whereas the laminae migrated to South America to form the 4 New-World species of camelidae. Tandem satellite arrays and interspersed repetitive DNA components of all South American camelidae and Camelus bactrianus have been identified. Comparison of these DNA components by Southern hybridization techniques using camel restriction fragments as probes, indicates that satellite DNA in these species has been conserved from a common ancestor dating back 5 to 10 million years.⁽¹⁹⁾ Recent studies using analysis of DNA sequence of the mitochondrial cytochrome b gene confirm the time of divergence of the Camelinae and Laminae tribes derived from fossil records. The origin of alpacas and llamas cannot be determined because hybridization occurred in the ancestry of both species.⁽¹⁷⁾ The close genomic kinship of New World camelidae is demonstrated by the analysis of DNA composition and in-situ hybridization of satellite fractions.⁽¹⁸⁾

The llama and guanaco have undifferentiated repetitive DNA patterns which supports the theory that llamas are a domesticated form of guanaco. In addition, vicuña patterns are specific and justify their classification in a separate genus. The alpaca displays intermediate DNA patterns suggesting that this species originated from a cross breeding between the guanaco and the vicuña.⁽¹⁹⁾

The dromedary (Camelus dromedarius) was domesticated some 5000 years ago (before 3000 B.C.) in the Arabian peninsula regions of Hadramout, Southern Yemen, and Oman. The name dromedary is derived from "dromos" or "road" in Greek, probably because they were initially used for transportation. The dromedary quickly became an integral part of the nomadic culture which was propagated throughout history from the Middle East to North Africa and from the Sahara desert to the sub-Saharan and other African countries. The dromedary in the Eastern part of Africa may have originated from individuals that were transported across the Red Sea from Yemen to Somalia and Ethiopia. In recent history (1800's), the dromedary was introduced to the USA and Australia.

The Bactrian camel (Camelus bactrianus), was domesticate a little bit later than the dromedary (around 2500 B.C.) in Turkmanestan and northern Iran. It was used as early as 300 B.C. as a pack animal and, with its cross with the dromedary, constituted most of the caravans trading along the famous silk road. There are only a few Bactrian camels left in the wild.

Two of the South American camelidae (the llama and alpaca) were domesticated several thousand years ago. The alpaca, especially valued for its fine fiber, became an important economic asset and a spiritual symbol for the Incan civilization. Domestication of the llama and alpaca dates back to 4000 years B.C.. The use of alpacas as a production animal was fully developed by the 11^th and 12^th centuries. This development took place under the Chimu and Chibcha cultures then spread to other places from the Titicaca Plateau. The name Alpaca comes from the Colla language and means spotted (allcca) and cinnamon (pacco) colored.

References

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