Evolution of the Ribosomal DNA Spacers of Drosophila melanogaster : Different Patterns of Variation on X and Y Chromosomes |
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| Authors: | Scott M. Williams Glenn R. Furnier Eric Fuog Curtis Strobeck |
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| Affiliation: | Department of Zoology, University of Alberta, Edmonton, Alberta T6G 2E9, Canada;Department of Forest Science, University of Alberta, Edmonton, Alberta T6G 2E9, Canada |
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| Abstract: | Length variation of the ribosomal gene spacers of Drosophila melanogaster was studied. Analysis of 47 X chromosomal and 47 Y chromosomal linked rDNA arrays collected from five continents indicates that the arrays on the two chromosomes differ qualitatively. The Y-linked arrays from around the world share little or no similarity for either their overall length or the organization of their spacers. Most of the X-linked arrays do, however, share a major length spacer of 5.1 kb. In addition, those X-linked arrays that have a major 5.1-kb band have similar spacer organization as demonstrated by genomic DNA digestions with several restriction enzymes. These data strongly support the hypothesis that spacer length patterns on only X-linked genes are maintained primarily by natural selection. |
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