Molecular Biology and Evolution, Vol 8, 104-114, Copyright © 1991 by Society for Molecular Biology and Evolution
K Tamura, T Aotsuka and O Kitagawa
Recent empirical and theoretical studies on mitochondrial DNA (mtDNA)
variation in higher animals have suggested that the extent of mtDNA
polymorphism is largely affected by spatial population subdivision. To
examine this we studied mtDNA polymorphism in two subspecies of Drosophila
sulfurigaster: D. s. albostrigata and D. s. bilimbata. Drosophila
sulfurigaster albostrigata is mainly distributed on the mainland of
Southeast Asia. In contrast, D. s. bilimbata forms discontinuous
populations on many islands scattered in the Pacific Ocean. Because of the
difference in their distribution patterns, the two subspecies are thought
to be different in the extent of spatial population subdivision. mtDNA was
isolated from greater than 50 isofemale strains for each subspecies and
were analyzed by eight restriction endonucleases. Nucleotide diversity
within a population was higher in D. s. albostrigata than in D. s.
bilimbata. However, haplotype diversity was 1.6 times greater in D. s.
bilimbata (0.85) than in D. s. albostrigata (0.53). The large difference in
overall heterogeneity was attributed to the difference in interpopulational
nucleotide diversity. For the two subspecies the proportion of
interpopulational gene diversity in a subdivided population was calculated
to be 0.54 in D. s. bilimbata and 0.40 in D. s. albostrigata. These
observations indicate that spatial population subdivision is a major factor
in determining mtDNA polymorphism in these subspecies. The extent of mtDNA
divergence between the subspecies was very high. The average nucleotide
divergence between them was 7.6%, which is almost the interspecific level
reported for other Drosophila species. The cause of the high degree of
mtDNA divergence is discussed.
ORIGINAL ARTICLE
Mitochondrial DNA polymorphisms in the two subspecies of Drosophila sulfurigaster: relationship between geographic structure of population and nucleotide diversity
Department of Biology, Tokyo Metropolitan University.
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