Dog breed diversity explained, according to reports in ScienceShots and Genome Research, Online 29 June 2006 and New Scientist, 1 July 2006, p18. Researchers at Uppsala University have compared the complete mitochondrial genomes from fourteen domestic dogs, six wolves, and three coyotes. They found the domestic dogs showed a greater variety in their DNA than the wolves, whom they are believed to have evolved from. The researchers concluded: “This suggests that a major consequence of domestication in dogs was a general relaxation of selective constraint on their mitochondrial genome. If this change also affected other parts of the dog genome, it could have facilitated the generation of novel functional genetic diversity. This diversity could thus have contributed raw material upon which artificial selection has shaped modern breeds and may therefore be an important source of the extreme phenotypic variation present in modern day dogs.”
Matthew Webster of Trinity College Dublin, who took part in the research, commented to New Scientist, “Our findings highlight the importance of mutation in driving evolution. With weaker natural selection, you can get a lot more changes in proteins that can be important in the future of the species.” Robert Wayne, an evolutionary biologist at John Hopkins University commented that mutations tended to accumulate more quickly in mitochondrial DNA than in the main store of DNA in the nucleus and therefore, “Much of the variation we see in dogs may have to do with pre-existing variation from the ancestral wolf-dog population. Relaxation of selection is likely to be only part of the answer.”
Editorial Comment: “Relaxation of selective constraint” means that dogs with genetic mutations that would have caused them to die out in the rough and tough naturally selecting world of wild animals, were able to survive and breed only because human beings cared for them. In other words: survival of the fittest had been eliminated. Natural selection was claimed by Darwin to give rise to new species, but in the case of wolves natural selection had obviously eliminated genetic novelties, and therefore had an anti-evolutionary effect. Robert Wayne’s comment is no help to the theory of evolution either. If wolf populations already contained many of the variations we see in domestic dogs, then dogs have reproduced after their kind – just as Genesis says, even if you arbitrarily give the wild wolf and the domestic dog different species names. (Ref. domestication, canines, genetics)
Evidence News 21st September 2006