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A comparative chromosome banding analysis of the Ursidae and their relationship to other carnivores

1987; Karger Publishers; Volume: 45; Issue: 3-4 Linguagem: Inglês

10.1159/000132455

1424-8581

William G. Nash, Stephen J. O’Brien,

Genetic Mapping and Diversity in Plants and Animals

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.