The dog was the first animal to be domesticated and the process started at least 15 000 years ago. Today it is the most morphologically diverse mammal, with a huge variation in size and shape. Dogs have always been useful to humans in several ways, from being a food source, hunting companion, guard, social companion and lately also a model for scientific research.
This thesis describes some of the changes that have occurred in the dog’s genome, both during the domestication process and later through breed creation. To give a more comprehensive view, three genetic systems were studied: maternally inherited mitochondrial DNA, paternally inherited Y chromosome and biparental autosomal chromosomes. I also sequenced complete mitochondrial genomes to view the effect new living conditions might have had on dogs’ genes after domestication. Finally, knowledge of the genetic structure in purebred dogs was used to test analytic methods usable in other species or in natural populations where little information is available.
The domestication process appears to have caused a relaxation of the selective constraint in the mitochondrial genome, leading to a faster rate of accumulation of nonsynonymous changes in the mitochondrial genes. Later, the process of breed creation resulted in genetically separated breed groups. Breeds are a result from an unequal contribution of males and females with only a few popular sires contributing and a larger amount of dams. However, modern breeder preferences might lead to disruptive selective forces within breeds, which can result in additional fragmentation of breeds. The increase in linkage disequilibrium that this represents increases the value of purebred dogs as model organisms for the identification and mapping of diseases and traits. Purebred dogs’ potential for these kinds of studies will probably increase the more we know about the dog’s genome.