Population genetics of the Y chromosome of Drosophila melanogaster: rDNA variation and phenotypic correlates

• Published in: Genetical Research Vol. 58; no. 1; pp. 7 - 13
• Main Authors: Clark, Andrew G., Szumski, Frances M., Lyckegaard, Eva M. S.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.08.1991
• Subjects: Animals; Biological and medical sciences; biological development; Blotting, Southern; Classical genetics, quantitative genetics, hybrids; DNA, Ribosomal - genetics; Drosophila melanogaster; Drosophila melanogaster - genetics; Drosophila melanogaster - growth & development; evolution; Female; Fundamental and applied biological sciences. Psychology; genes; Genetic Variation; Genetics of eukaryotes. Biological and molecular evolution; Genetics, Population; Invertebrata; Kinetics; length; Male; Phenotype; phenotypic correlation; population genetics; ribosomal DNA; Selection, Genetic; setae (animal); sex linkage; Y Chromosome; Insecta; Ribosomal DNA; Setae; Y-Chromosome; Population genetics; Drosophilidae; Substitution line; Arthropoda; Development; Invertebrata; Drosophila melanogaster; Diptera; Polymorphism
• ISSN: 0016-6723; 1469-5073
• DOI: 10.1017/S0016672300029554

One means of examining the evolutionary significance of molecular variation on the Y chromosome is to identify phenotypes specifically affected by Y-linked genes, and to quantify the phenotypic variation and its correlation to the molecular variation. The functional importance of the Y-linked array of rRNA genes is demonstrated by the ability of Y chromosome to rescue X-linked bobbed lethal alleles, whose lethality is seen in homozygous females. Because low numbers of X-linked rDNA gene copies result in increased developmental time and shortened bristles, and because there is considerable natural variation in Y-linked copy number, a careful examination of Y-linked variation in these two traits may uncover a mode of selection acting on the multigene family. In this study, 36 Y-chromosome replacement lines were tested to detect subtle variation in bristle phenotypes and developmental rates. Correlations among these traits, rDNA gene copy number, and intergenic sequence length were quantified. The absence of significant correlations between phenotypic characters and rDNA copy number or intergenic sequence length suggests that the extant molecular variation in Y-linked rDNA can have at most very small selective effects.