Selection for Increased Longevity in <i>Drosophila melanogaster</i><i>:</i> A Reply to Lints

Abstract

An important tool in the genetic analysis of longevity and aging in Drosophila melanogaster is the use of strains selected directly for late-age reproduction and indirectly for extended longevity. Following some initial failures to select for extended longevity, there are now a number of laboratories which have successfully selected for long life, using the techniques of late-age reproduction as well as selection for stress resistance. Baret and Lints [Gerontology 1993;39:252–259] have recently cast doubt on the reality of a number of these selected strains, including our own, suggesting that the difference in longevity between the long-lived and normal-lived strains disappears when the data are examined as a function of the number of days after the beginning of the selection experiment instead of as a function of the number of generations. With regard to our selected lines, they based their analysis on a subset of the published data dealing with these strains, and which covered 21 generations, or 40 months, of selection. We now present data for over 70 generations, or 155 months, of selection and maintenance. The Baret-Lints hypothesis makes two strong predictions, namely that (1) the longevity difference between the several strains should disappear when the data are replotted according to their fashion, and (2) there should be no other significant biological difference between the strains. Our data falsifies both of these predictions. The Baret-Lints hypothesis is flawed and should be disregarded. We also show that (1) the variations about the mean for six different genetically isolated strains of different longevities may be attributed to temporal alterations in the laboratory environment and (2) these variations do not obscure the genetic determinism of longevity.

Selection for Increased Longevity in <i>Drosophila melanogaster</i>: Reflections on New Data

“…In the studies of Fukui et al [3] and Arking and Buck [4], there is a difference when simulta neous comparisons are made. Yet, when Baret and Lints [2] published their paper, data showing a longer longevity in late-reproduced lines were not published.…”

“…They were probably poorly controlled, as in Luckinbill and Clare's experiments, where the developmental time varied beween 7 and 10 days at low larval density and between 9 and 18 days at high larval density. Such varia tions are not expected in controlled develop mental conditions [6], Arking and Buck [4] published data col lected during a 13-year period, from the be ginning of Luckinbill and Clare's experiment until 1994. These data are new and interest ing, but very imprecise.…”

“…and F.A.L. proposed a reinterpretation of the late-age reproduction experiments of Luckinbill and Clare [1], The difference they reported between early-repro duced and late-reproduced lines disappeared when the mean life span was plotted as a func tion of the number of days elapsed since the initiation of the experiment rather than as a function of the number of generations [2], In two recent papers [3,4], new data were pre sented as contradictory with that reinterpretation. However, both series of authors agreed with us about the importance of a comparison as a function of the number of days elapsed since the initiation of the experiment.…”

A mini-review of the evolutionary theories of aging.

“…In other words, when YOUNG and OLD flies living at the same moment are compared, there is no longevity difference between them. This article provoked considerable attention (see the debate in Gerontology: Fukui, Pletcher and Curtsinger 1995;Arking and Buck 1995;Baret, Le Bourg and Lints 1996). Arking and Buck (1995) published new results using the lines of Luckinbill et al (1984) showing clear differences between OLD and control lines reproduced at random age.…”

“…This article provoked considerable attention (see the debate in Gerontology: Fukui, Pletcher and Curtsinger 1995;Arking and Buck 1995;Baret, Le Bourg and Lints 1996). Arking and Buck (1995) published new results using the lines of Luckinbill et al (1984) showing clear differences between OLD and control lines reproduced at random age. However, these new results also showed that these differences appeared very late, not before the 30 th month of selection, which confirms that no increased longevity in OLD lines was observed in the article of Luckinbill and Clare (1985).…”