Different rates of divergence in highly repetitive DNA of cetaceans

ARNASON, U. and WIDEGREN, B. 1984. Different rates of divergence in highly repetitive DNA of cetaceans. —Hereditas 101:171–177. Lund, Sweden. ISSN 0018–0661.

Three highly repetitive components of cetacean genomes were studied. Two of the components were isolated from balenopterid DNA by isopycnic ultracentrifugation. These components were referred to as H (heavy) and L (light) satellites, respectively. The third component was isolated as a restriction fragment, 1730 bp in length. Molecular hybridization and restriction analysis showed that the 1730 bp fragment was highly conserved in both mysticetes and odontocetes, two lineages that separated some 45 million years ago. Digestion with Xba I showed that the repeat length of the H satellite was 420 bp in the three balenopterids studied. Sequences related to the H satellites occur outside the balenopterids. The L satellite is a balenopterid characteristic. The L satellite did not hybridize with DNA of species outside the genus Balaenoptera. Irrespective of the supposed younger age of the L satellite, hybridization with this component to restricted DNA showed great variation between the three balenopterid species. The L satellite is evidently evolving much faster than the other two components.