Chromosome polymorphism and karyotype evolution of four canids: the dog, red fox, arctic fox and raccoon dog

In the family Canidae a wide range of the diploid chromosome numbers is observed, from 34 + B in the red fox to 78 in the dog and the wolf. Moreover, extensive chromosome polymorphisms were described in some species. In the red fox and raccoon dog a variable number of B chromosomes exist, while in the arctic fox such variability is caused by the widely spread Robertsonian translocation. Also size polymorphism of heterochromatic arms appears in the arctic fox. During the last ten years very rapid progress has been achieved in the mapping of the dog genome and it has facilitated the construction of genome maps of other canids, as well. The application of the comparative chromosome painting approach and the analysis of the chromosome localisation of marker loci have facilitated detailed studies on chromosome rearrangements which occurred during the karyotype evolution. It is foreseen that the extended knowledge on the canine genome organisation will be useful not only in the detection of gene mutations causing hereditary diseases in the dog, but also will facilitate the identification of genes responsible for the great phenotypic and behavioural variability of the dog breeds. Potentially this knowledge may also be useful in fur animal breeding.