The karyotypes of most birds consist of a small number of macrochromosomes and numerous microchromosomes. Intriguingly, most accipitrids which include hawks, eagles, kites, and Old World vultures (Falconiformes) show a sharp contrast to this basic avian karyotype. They exhibit strikingly few microchromosomes and appear to have been drastically restructured during evolution. Chromosome paints specific to the chicken (GGA) macrochromosomes 1-10 were hybridized to metaphase spreads of three species of Old World vultures (Gyps rueppelli, Gyps fulvus, Gypaetus barbatus). Paints of GGA chromosomes 6-10 hybridize only to single chromosomes or large chromosome segments, illustrating the existence of high chromosome homology. In contrast, paints of the large macrochromosomes 1-5 show split hybridization signals on the chromosomes of the accipitrids, disclosing excessive chromosome rearrangements which is in clear contrast to the high degree of chromosome conservation substantiated from comparative chromosome painting in other birds. Furthermore, the GGA chromosome paint hybridization patterns reveal remarkable interchromosomal conservation among the two species of the genus Gyps.
2006 S. Karger AG, Basel.