Plant & Animal Genomes XIII Conference Plant & Animal Genomes XIII ConferenceJanuary 15-19, 2005
Town & Country Convention Center
San Diego, CA
Domestic horses, other exotic equids, and rhinoceroses are close relatives belonging to the Order Perissodactyla. While the equids have undergone rapid karyotypic evolution, with a diploid chromosome number ranging from 2N=32 to 2N=66 depending on species, rhinoceroses have retained a stable karyotype of either 2N=82 or 2N=84 chromosomes. As the Horse Genome Project has progressed, several hundred markers have been physically mapped to horse chromosomes enabling comparisons of the horse and the human genomes. Additionally, these same horse markers can be used to create low density comparative gene maps for other endangered Perissodactyls. Using FISH, we have created comparative maps for the Przewalski horse and onager. Most recently, we have created comparative maps for Indian, Sumatran, Northern and Southern White, and Eastern and Southern Black rhinoceroses.
Our results indicate that a high degree of genome conservation was observed between the Przewalski horse and domestic horse with only one chromosome fission/fusion event separating the two species, while numerous changes were observed between the horse and the onager. Surprisingly, gene order was conserved among rhinoceros species and between rhinoceroses and the domestic horse even though centromere positions were quite different. Overall, markers derived from horse metacentric autosomes maintained a conserved gene order on acrocentric rhinoceros chromosomes. Differences in chromosome morphology between the horse and rhinoceroses could be attributed to centromere fission/fusion events, inversions, and potentially to translocations and neocentromere formation.
**This research was funded by the Morris Animal Foundation