A surprising study reveals that there is a trace of "wolf" lurking within the tiny body of a Chihuahua and the gigantic build of a St. Bernard.
An international research team from the American Museum of Natural History and the National Museum of Natural History analyzed the genomes of 2,693 dogs and wolves and found that 64.1 percent of purebred dogs carry fragments of wolf DNA. Furthermore, a study of village dogs (free-roaming dogs living in or near human communities) from around the world found genetic traces of wolves in all 280 analyzed pups.
Dogs are thought to have evolved from populations of gray wolves, which became extinct during the Late Pleistocene epoch about 20,000 years ago. Although wolves and dogs still share habitats and can produce fertile offspring, interbreeding between the two has been thought to be extremely rare. Apart from deliberate breeding, there has been little evidence of genetic mixing since domestication.
“Prior to this study, the leading science seemed to suggest that in order for a dog to be a dog, there can’t be very much wolf DNA present, if any,” explains Audrey Lynn, a postdoctoral fellow at the American Museum of Natural History who specializes in bioinformatics. “But we found if you look very closely in modern dog genomes, wolf is there.”
Genomes Reveals Memories From 3,000 Years Ago
Lynn and her colleagues collected large-scale genome data from the National Center for Biotechnology Information and the European Nucleotide Archive (ENA) and used sensitive genomic methods such as local ancestry analysis (LAI) and phylogenetic analysis to study wolves, purebred canines, village dogs, and other canids from the late Pleistocene to the present. The research was conducted using highly sensitive genomic methods such as local ancestry estimation (LAI) and phylogenetic analysis.
By combining these advanced methods, the researchers were able to divide the entire genome into smaller sections, estimate the ancestry of each section, and capture minute amounts of gene flow that could not be detected using conventional statistical methods.
They found that the gene flow from wolves to dogs occurred on average about 1,000 generations ago (equivalent to about 3,000 years ago). In contrast, the gene flow from dogs to wolves was much more recent, concentrated around the beginning of the 19th century. This is thought to be related to the increase in stray dog populations that accompanied urbanization and the expansion of human activity.