Phylogenetic implications of the 38 putative ancestral chromosome segmentsfor four canid species

Chromosome homologies between the Japanese raccoon dog (Nectereutes procyon oides viverrinus, 2n = 39 + 2-4 B chromosomes) and domestic dog (Canis fami liaris, 2n = 78) have been established by hybridizing a complete set of can ine paint probes onto high-resolution G-banded chromosomes of the raccoon d og. Dog chromosomes 1, 13, and 19 each correspond to two raccoon dog chromo some segments, while the remaining 35 dog autosomes each correspond to a si ngle segment. In total, 38 dog autosome paints revealed 41 conserved segmen ts in the raccoon dog. The use of dog painting probes has enabled integrati on of the raccoon dog chromosomes into the previously established comparati ve map for the domestic dog, Arctic fox (Alopex lagopus), and red fox (Vulp es vulpes). Extensive chromosome arm homologies were found among chromosome s of the red fox, Arctic fox, and raccoon dog. Contradicting previous findi ngs, our results show that the raccoon dog does not share a single biarmed autosome in common with the Arctic fox, red fox, or domestic cat. Comparati ve analysis of the distribution patterns of conserved chromosome segments r evealed by dog paints in the genomes of the canids, cats, and human reveals 38 ancestral autosome segments. These segments could represent the ancestr al chromosome arms in the karyotype of the most recent ancestor of the Cani dae family, which we suggest could have had a low diploid number, based on comparisons with outgroup species. Copyright (C) 2001 S. Karger AG, Basel.