17.08.2020: The genetic diversity and global migration patterns of dromedaries – an animal species that is becoming increasingly important in the context of climate change – follow old caravan routes, this is the central message of a recent study published by an international research team led by Vetmeduni Vienna in Nature Communications Biology. The scientists analyzed a global dataset that includes more than 22.000 genome wide markers of dromedaries on three continents.

Dromedaries were essential for the prosperity of civilizations in arid regions and the spread of people, goods and cultures along old, cross-continental trade routes. As desertification increases, its importance as an animal continues to grow, but little has been known about its genome-wide diversity and demographic history.

Genetic diversity as a result of the last Ice Age and the expansion of the Ottoman Empire

The research team led by Vetmeduni Vienna has now been able to demonstrate significant population differentiation of dromedaries in Asia and Africa through a genome-based approach. In addition, the scientists were able to trace the spread of the ungulates after domestication on historical caravan routes such as the Silk and Incense Road. But this is not all, as Pamela Burger from the Research Institute of Wildlife Ecology at Vetmeduni Vienna explains: "Our results show for the first time that the decline of the population during the last ice age and expansion movements in the Middle Ages during the rise of the Ottoman Empire have shaped the genetic diversity of modern dromedaries. This new understanding of the population structure also underlines the value of small, locally adapted populations. We therefore call for the safeguarding of genetic diversity and the sustainable use of this species, which is so important for deserts and dry areas."

New insights into evolutionary history through genome analysis

This study shows that the assessment of the evolutionary history of species using genome-based approaches allows detailed conclusions to be drawn about population structure, migration and propagation movements, and possible signals for adaptation to the environment. Since the movements of the dromedaries correspond to those of man, the knowledge of spatial genetic signatures of the dromedaries also sheds new light on the past of mankind. The scientists found corresponding genetic evidence in continental populations (Asia and Africa), which underlines the strong anthropogenic influence on this species.

"The genetic diversity that we have been able to highlight in this study is a result of a consistent genetic mixing due to historical and recent movements along the trade routes. This may have led to a unique genetic material that could make camels more resilient to global environmental change and therefore must be preserved," said first author Sara Lado.

Dromedaries and camels – important species against the background of climate change

As one of the last domesticated animals – it took place only about 3.000 to 4.000 years ago – the dromedary (Camelus dromedarius) occupies a special position in human migration and trade. Its physiological adaptations to harsh and dry environments allowed humans to traverse hostile regions such as deserts and allowed the expansion of civilizations. Their superior and unique characteristics predestined dromedaries for use as military animals and for international trade along historic caravan routes such as the Silk Road and the Incense Route. The hybridization between dromedaries and the closely related two-honed bactrian camel (Camelus bactrianus) produced even more robust and durable animals suitable for the extreme climatic conditions of the Silk Road. Today, dromedaries and Bactrian camels are the most important animal species in desert areas. Their impact on land and water resources for food production is less than for any other crop. As desertification and global climate change increase, their importance will therefore increase, according to the researchers.

The article „Genome-wide diversity and global migration patterns in dromedaries follow ancient caravan routes“ by Sara Lado, Jean Pierre Elbers, Angela Doskocil, Davide Scaglione, Emiliano Trucchi, Mohammad Hossein Banabazi, Faisal Almathen, Naruya Saitou, Elena Ciani and Pamela Anna Burger was published in Nature Communications Biology.