[Dogs, wolves and genes]

The most significant polymorphism associated with dog size occurs in the region of the IGF1 gene and concerns a single base change in a neighbouring lncRNA. The "small" (C) allele of this SNP is mostly found in small modern breeds and canids (foxes, coyotes, jackals) while the "large" (T) dominates in wolves and large dogs. However, the small allele is also present at low level in ancient wolves and is shown to represent the ancestral allele in canids, which has been recently selected in small dog breeds obtained by human selection.