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Summary: 1822
2001 The Society for the Study of Evolution. All rights reserved.
Evolution, 55(9), 2001, pp. 18221831
DECLINE IN OFFSPRING VIABILITY AS A MANIFESTATION OF AGING IN
DROSOPHILA MELANOGASTER
STEFANIE KERN, MARTIN ACKERMANN, STEPHEN C. STEARNS, AND TADEUSZ J. KAWECKI1
Unit for Ecology and Evolution, Department of Biology, University of Fribourg, Chemin du Musee 10, CH-1700
Fribourg, Switzerland
Abstract. The evolutionary explanation of senescence proposes that selection against alleles with deleterious effects
manifested only late in life is weak because most individuals die earlier for extrinsic reasons. This argument also
applies to alleles whose deleterious effects are nongenetically transmitted from mother to progeny, that is, that affect
the performance of progeny produced at late ages rather than of the aging individuals themselves. We studied the
effect of maternal age on offspring viability (egg hatching success and larva-to-adult survival) in two sets of Drosophila
melanogaster lines (HAM/LAM and YOUNG/OLD), originating from two long-term selection experiments. In each
set, some lines (HAM and YOUNG, respectively) have been selected for early reproduction, whereas later reproduction
was favored in their counterparts (LAM and OLD). In the HAM and LAM lines, both egg hatching success and larval
viability declined with mother's age and did so with accelerating rates. The hatching success declined significantly
faster with maternal age in HAM than in LAM lines, according to one of two statistical approaches used. Egg hatching
success also declined with maternal age in YOUNG and OLD lines, with no difference between the selection regimes.
However, the relationship between mother's age and offspring larva-to-adult viability differed significantly between
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