Genetic changes within an aphid clone: homogenization of rDNA intergenic spacers after insecticide selection |
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| Authors: | KEVIN A SHUFRAN Z B MAYO TERESA J CREASE |
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| Institution: | USDA-ARS, Plant Science and Water Conservation Research Laboratory, 1301 N. Western Road., Stillwater, OK 74075, USA;Department of Entomology, 202 Plant Industry Building, University of Nebraska, Lincoln, NE 68583, USA;Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1, Canada |
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| Abstract: | A single asexual maternal lineage (i.e. clone) of the greenbug aphid, Schizaphis graminum (Rondani) was repeatedly selected with the insecticide disulfoton ( O , O -diethyl S- 2-(ethylthio)ethyl] phosphorodioate). A parallel colony of the non-selected clone was also maintained. After approximately 200 generations (4 years) of continuous selection, both the selected and non-selected clones were assayed for changes in intergenic spacer (IGS) length variants of the rRNA cistron. No changes in sets of IGS variants were detected in the non-selected clone. However, the selected clone was found to have lost three variants present in the non-selected clone. This probably occurred by unequal cross-over between sister chromatids, whereby the cistron became homogenized by an increase of frequency of two smaller variants. This documents a large-scale genetic change occurring within the rRNA cistron in a parthenogenetically reproducing aphid. © 2003 The Linnean Society of London. Biological Journal of the Linnean Society , 2003, 79 , 101–105. |
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| Keywords: | Aphididae chromosomal rearrangements concerted evolution greenbug molecular drive ribosomal DNA |
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