EVOLUTION OF REPEATED SEQUENCE ARRAYS IN THE D-LOOP REGION OF BAT MITOCHONDRIAL-DNA

Analysis of mitochondrial DNA control region sequences from 41 species of bats representing 11 families revealed that repeated sequence arra ys near the tRNA-Pro gene are present in all vespertilionine bats. Acr oss 18 species tandem repeats varied in size from 78 to 85 bp and cont ained two to nine repeats. Heteroplasmy ranged from 15% to 63%. Fewer repeats among heteroplasmic than homoplasmic individuals in a species with up to nine repeats indicates selection may act against long array s. A lower limit of two repeats and more repeats among heteroplasmic t han homoplasmic individuals in two species with few repeats suggests l ength mutations are biased. Significant regressions of heteroplasmy, t heta and pi, on repeat number further suggest that repeat duplication rate increases with repeat number. Comparison of vespertilionine bat c onsensus repeats to mammal control region sequences revealed that tand em repeats of similar size, sequence and number also occur in shrews, cats and bighorn sheep. The presence of two conserved protein-binding sequences in all repeat units indicates that convergent evolution has occurred by duplication of functional units. We speculate that D-loop region tandem repeats may provide signal redundancy and a primitive re pair mechanism in the event of somatic mutations to these binding site s.