期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1987
卷号：84
期号：2
页码：610-614
DOI：10.1073/pnas.84.2.610
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Selection for "fast" preadult development rate among the progeny of flies collected in a natural population of Drosophila melanogaster produced a line that developed more rapidly than a line selected for "slow" preadult development rate. Assays for enzyme activity levels showed that the activities of alpha-glycerophosphate dehydrogenase, alcohol dehydrogenase, and malic enzyme were higher in the fast than in the slow line, but that the activity of superoxide dismutase was lower in the fast line. Differences in the frequencies of spacer-length phenotypes of X chromosome-linked rRNA genes (rDNA), which developed between the lines during the selection process, are larger than can be explained on the basis of genetic drift alone. Long rDNA spacers had high frequency in the fast line; short spacers, in the slow line. We conclude that enzyme levels affected adaptation under the selective regimes imposed and that the different X-linked rDNA spacer-length phenotypes are either adaptive in themselves or that they mark chromosomal segments carrying genes relevant to adaptation.
