Evolutionary effects of selection on age at reproduction in larval and adult Drosophila melanogaster

Abstract

Two sets of three replicate lines of Drosophila melanogaster were artificially selected by reproduction at either a "young' or an "old' age. The pure lines, the hybrids between the lines within a selection regimen and the base stock from which the lines were derived were compared for longevity, early and late fertility, development time, larval viability and adult thorax length. Comparison of hybrid with pure lines showed some evidence for inbreeding depression in the lines from both selection regimes. Comparison of hybrid lines with the base stock did not provide evidence for any trade-off in either males or females between early fertility on the one hand and late life fertility and longevity on the other. Nor was there any clear evidence of a trade-off between pre-adult and adult fitness components. There was evidence of inadvertent selection for rapid development in both selection regimes, especially in the females of the "young' lines. This complicated interpretation of the responses and correlated responses to selection. An improvement in adult performance in the "old' line males relative to the base stock appeared to be attributable to reversal of mutation accumulation. Comparison of the hybrid "young' and "old' lines with the base stock did not support the idea that the superior longevity and late life fertility of the "old' lines could be accounted for by the effects of mutation accumulation in the "young' lines. -from Authors