Domestication: a long process

When and where did modern camels evolve? This question of evolutionary history and domestication of dromedary (Camelus dromedarius) and Bactrian camel (C. bactrianus) reached the field of molecular genetics only recently. Within Old World camels the split between dromedaries and Bactrians was dated at 5 million years (myr) before Common Era (BCE), significantly later than estimated by phylogenetic studies (8 myr). Based on archaeological data the domestication of dromedaries took place in the Southeastern part of the Arabian Peninsula, 3000-4000 years ago. The originally assumed and eponymous center of origin for two-humped camels in Bactria (today’s Afghanistan, Turkmenistan) has been replaced by possible domestication center(s) in Western Asia, 5000-6000 years ago.

For both species, we collected samples from populations worldwide. Genetic data give us insight into ancient demographic events, since they have left imprints in their genetic profiles. Basically, we follow two main hypotheses:

• The multiregional hypothesis suggests that modern camels evolved directly from ancient wild forms in several different locations in the Old World.

• The single origin model defines a specific population – a separate for each (dromedary and Bactrian camel) – that underwent domestication followed by demographic expansion.

To test these hypotheses we use mitochondrial DNA (mtDNA) inherited solely from the mother and nuclear DNA transferred by both parents to the offspring.

Hybridization between wild and domestic Bactrian camels

Hybridization between wild species and their domestic congeners often threatens the gene pool of the wild species. The last wild camel population in Mongolia is one example of such a hybridization threat, since the presence of hybrid camels within the wild population in the Great Gobi Strictly Protected Area ‘A’ (GGSPAA) was observed. Furthermore, the hybridization between female domestic Bactrian and male wild camels in the buffer zone of the GGSPAA was identified as major problem. We use mitochondrial DNA PCR-Restriction Fragment Polymorphism analysis and nuclear microsatellite markers to investigate the extend of hybridization within the Mongolian wild camel population.