On the origin of mongrels: evolutionary history of free-breeding dogs in Eurasia

Although a large part of the global domestic dog population is free-ranging and free-\udbreeding, knowledge of genetic diversity in these free-breeding dogs (FBDs) and their\udancestry relations to pure-breed dogs is limited, and indigenous status of FBDs in Asia is\uduncertain. We analyse genome-wide SNP variability of FBDs across Eurasia, and show\udthat they display weak genetic structure, and are genetically distinct from pure-breed\uddogs rather than constituting an admixture of breeds. Our results suggest that modern\udEuropean breeds originated locally from European FBDs. East Asian and Arctic breeds\udshow closest affinity to East Asian FBDs, and they both represent earliest-branching\udlineages in the phylogeny of extant Eurasian dogs. Our biogeographic reconstruction of\udancestral distributions indicates a gradual westward expansion of East Asian indigenous\uddogs to the Middle East and Europe through Central and West Asia, providing evidence\udfor a major expansion that shaped the patterns of genetic differentiation in modern\uddogs. This expansion was probably secondary and could have led to the replacement of\udearlier resident populations in Western Eurasia. This could explain why earlier studies\udbased on modern DNA suggest East Asia as the region of dog origin, while ancient DNA\udand archaeological data point to Western Eurasia