Ancient and modern DNA reveal dynamics of domestication and cross-continental dispersal of the dromedary

Dromedaries have been fundamental to the development of human societies in arid landscapes and for long-distance trade across hostile hot terrains for 3,000 y. Today they continue to be an important livestock resource in marginal agro-ecological zones. However, the history of dromedary domestication and the influence of ancient trading networks on their genetic structure have remained elusive. We combined ancient DNA sequences of wild and early-domesticated dromedary samples from arid regions with nuclear microsatellite and mitochondrial genotype information from 1,083 extant animals collected across the species’ range. We observe little phylogeographic signal in the modern population, indicative of extensive gene flow and virtually affecting all regions except East Africa, where dromedary populations have remained relatively isolated. In agreement with archaeological findings, we identify wild dromedaries from the southeast Arabian Peninsula among the founders of the domestic dromedary gene pool. Approximate Bayesian computations further support the “restocking from the wild” hypothesis, with an initial domestication followed by introgression from individuals from wild, now-extinct populations. Compared with other livestock, which show a long history of gene flow with their wild ancestors, we find a high initial diversity relative to the native distribution of the wild ancestor on the Arabian Peninsula and to the brief coexistence of early-domesticated and wild individuals. This study also demonstrates the potential to retrieve ancient DNA sequences from osseous remains excavated in hot and dry desert environments

Body condition scores at calving and their association with dairy cow performance and health in semiarid environment under two cooling systems

Under tropical environments cow’s body condition at calving may influence productivity and health performance. Therefore, the current research evaluated the impact of body condition score (BCS) at calving on milk production traits and health problems of primiparous and multiparous cows raised under two cooling systems in semi-arid environment. Milk yield parameters and health disorders data at different parities were obtained from 1700 Holstein cows, which were managed under Korral Kool (KKC) and fan (FC) cooling systems in Saudi Arabia. The results revealed that KKC system induced high level of milk production improvement (305TM, days in milk, daily milk yield) (P<0.05) compared to FC, especially in multiparous cows. There was an advantage of the high BCS group under KKC system over the FC system for peak yield and period. Cows from both cooling systems having moderate BCS outdid the other groups for total milk yield. Low BCS primiparous cows reared under KKC system were the most to suffer from stillbirth (18%), and calving ease (26.1%) in winter, while high BCS were the most to be treated for mastitis (8.5% in summer). On the other hand, spring calved multiparous cows raised under FC system suffered more from lameness (21.57% - high BCS) and milk fever (4.4% - moderate BCS). Further, cows having moderate BCS kept under KKC system had the highest incidence of lameness (62.2%), and abomasum displacement (4.4%). In conclusion, achieving correct BCS at calving and cooling system is important to avoid calving subsequent lactation performance and metabolic disease losses

Drom970_17msat

This data matrix contains the raw data of 17 microsatellite loci genotyped in 970 dromedaries from 36 populations worldwide

Data from: Ancient and modern DNA reveal dynamics of domestication and cross-continental dispersal of the dromedary

Dromedaries have been fundamental to the development of human societies in arid landscapes and for long-distance trade across hostile hot terrains for 3,000 y. Today they continue to be an important livestock resource in marginal agro-ecological zones. However, the history of dromedary domestication and the influence of ancient trading networks on their genetic structure have remained elusive. We combined ancient DNA sequences of wild and early-domesticated dromedary samples from arid regions with nuclear microsatellite and mitochondrial genotype information from 1,083 extant animals collected across the species’ range. We observe little phylogeographic signal in the modern population, indicative of extensive gene flow and virtually affecting all regions except East Africa, where dromedary populations have remained relatively isolated. In agreement with archaeological findings, we identify wild dromedaries from the southeast Arabian Peninsula among the founders of the domestic dromedary gene pool. Approximate Bayesian computations further support the “restocking from the wild” hypothesis, with an initial domestication followed by introgression from individuals from wild, now-extinct populations. Compared with other livestock, which show a long history of gene flow with their wild ancestors, we find a high initial diversity relative to the native distribution of the wild ancestor on the Arabian Peninsula and to the brief coexistence of early-domesticated and wild individuals. This study also demonstrates the potential to retrieve ancient DNA sequences from osseous remains excavated in hot and dry desert environments