Genetic diversity and population structure of dromedary camel-types.

The dromedary camel is a unique livestock for its adaptations to arid-hot environments and its ability to provide goods under extreme conditions. There are no registries or breed standards for camels. Thus, named camel populations (i.e. camel-types) were examined for genetic uniqueness and breed status. Camel populations are generally named based on: shared phenotype, country or region of origin, tribal ownership, or the ecology of their habitat. A dataset of 10 Short-Tandem Repeat markers genotyped for 701 individual camels from 27 camel-types was used to quantify genetic diversity within camel-types, compare genetic diversity across camel-types, determine the population genetic structure of camel-types, and identify camel-types that may represent true breeds. Summary statistics (genotyping call rate, heterozygosity, inbreeding coefficient FIS, and allelic frequencies) were calculated and population-specific analyses (pairwise FST, neighbor-joining tree, relatedness, Nei's genetic distance, PCoA, and STRUCTURE) were performed. The most notable findings were: (1) little variation in genetic diversity was found across the camel-types, (2) the highest genetic diversity measure was detected in Targui and the lowest was in Awarik, (3) camel-types from Asia (especially the Arabian Peninsula) exhibited higher genetic diversity than their counterparts in Africa, (4) the highest DeltaK value of population structure separated camel-types based on geography (Asia vs. Africa), (5) the most distinct camel-types were the Omani, Awarik, and the Gabbra, (6) camel-types originating from the same country did not necessarily share high genetic similarity (e.g. camel-types from Oman), and (7) camel-type names were not consistently indicative of breed status.