A comparative chromosome banding analysis of the Ursidae and their relationship to other carnivores.
Trypsin G-banded karyotypes of eight species of Ursidae were prepared from retrovirus-transformed skin fibroblast cultures. The banding patterns of all bears are highly conserved, even though their diploid numbers range from 42 to 72. A comprehensive analysis of the homologous banding patterns within the Ursidae and with a hypothesized ancestral carnivore karyotype permitted the reconstruction of three significant chromosomal reorganization events that occurred during the evolution of the modern ursids. The first was a multichromosomal fissioning away from the biarmed (2n = 44) primitive carnivore karyotype, leading to six species of the Ursinae subfamily (2n = 78). The second was a comprehensive chromosome fusion in the lineage that led to the Ailuropodinae (giant panda) subfamily (2n = 44). The third event was a second, independent, but less extensive, centromeric fusion occurring in the line that led to the Tremarctinae (spectacled bear) subfamily (2n = 52). Ursidae karyotypes are not only highly conserved within the family but also exhibit extensive chromosome banding homology with other carnivore families.
H & W Cytogenetic Services, Inc., Sterling, VA.
W G
WG
Nash
S J
SJ
O'Brien
D000818:Animals; D000836:Animals, Zoo; D005075:Biological Evolution; D002335:Carnivora / Q000235:genetics*; D002478:Cells, Cultured; D002871:Chromosome Banding; D005260:Female; D005347:Fibroblasts / Q000648:ultrastructure; D007621:Karyotyping; D008297:Male; D012867:Skin / Q000648:ultrastructure; D013045:Species Specificity; D001503:Ursidae / Q000235:genetics*