GENERATION OF VNTRS AND HETEROPLASMY BY SEQUENCE TURNOVER IN THE MITOCHONDRIAL CONTROL REGION OF 2 ELEPHANT SEAL SPECIES

We describe an unusual repetitive DNA region located in the 3' end of the light (L)-strand in the mitochondrial control region of two elepha nt seal species. The ar-ray of tandem repeats shows both VNTR (variabl e-number tandem repeat) and sequence variation and is absent from 12 c ompared mammalian species, except for the occurrence in the same locat ion of a distinct repetitive region in rabbit mtDNA and a similar repe at in the harbor seal. The sequence composition and arrangement of the repeats differ considerably between the northern elephant seal (Mirou nga angustirostris) and the southern species (M. leonina) despite an e stimated divergence time of 1 MY (based on an mtDNA-RNA gene and the n onrepetitive control region). Analysis of repeat sequence relationship s within and between species indicate that divergence in sequence rand structure of repeats has involved both slippagelike and unequal cross ingover processes of turnover, generating very high levels of divergen ce and heteroplasmy.