The Genotypic Control of Longevity in Drosophila Melanogaster Under Two Environmental Regimes

Abstract

SummaryLongevity in four inbred strains and their hybrids has been studied at two temperatures, 29·5 and 25°C. Heterosis was found at both temperatures but was more extreme at 29· 5°C, which is a very unfavourable environment for D. melanogaster. This observation has its parallel in observations on various fitness factors in several organisms. At 29· 5°C there was more variability of a genotypic nature between the hybrids than at 25°C, perhaps because the adaptation to this unfavourable environment depencls on rather special gene combinations. Thus longevity varies between genotypes, but the pattern of variation depends in an intimate way on the environment.

Genetical and maternal determinants of the activity and preening behaviour of Drosophila melanogaster reared in different environments

“…Otherwise, when left in the less favourable conditions of the original vials, the death rate of 6C/L was far higher than that of Edinburgh and the males of the two strains proved the less hardy sex, confirming both our observations on the culture bottles and the evidence of Parsons (1966) on sex differences in the longevity of D. melanogaster.…”

“…Inbreeding may also influence the relationship between viability and the genetical architecture of activity, although there is not the simple decrease in activity with increased inbreeding which Harland and Jackson (1958) proposed; for instance, 6C/L had been inbred for 150 generations at the time of the diallels and Samarkand for 280, but Wellington, which was far more active than the latter, for 750 generations. It has frequently been demonstrated in Drosophila (Jinks and Mather, 1955;Breese and Mather, 1960;Parsons, 1966) that heterozygotes have a higher viability than inbred lines and that their performance on both morphological and behavioural measures is far less affected by environmental changes. Therefore, the changes in the genetical control, and especially the reversal of the direction of dominance, between the fresh and original conditions of rearing, are due to the high mortality of the less active flies affecting the inbred lines but not the F1s.…”

Extreme-environment heterosis and genetic loads

“…larval survival (Parsons, 1959) and longevity (Parsons, 1966) in D. melanogaster and growth rates in Arabidopsis thaliana (Langridge, 1962) and maize (McWilliam and Griffing, 1965)] and low temperatures [viability in D. melanogaster (Fontdevila, 1970) and growth rates in maize (McWilliam and Griffing, 1965)]. A further very good example in plants comes from Bucio Alanis, Perkins and Jinks (1969) in .1'Iicotiana rustica, where over a series of environments the magnitude of heterosis for crosses between inbred strains was found to fall off as the environment improves.…”

Interactive effects of temperature and geography on emigration behavior of Drosophila melanogaster. II. Further studies on geographical differences.

“…In Setouchi district flies encounter fairly high temperature in summer, and flies must move to avoid the deleterious condition due to high temperature. Otherwise flies will not survive (Parsons 1966), and reproduce poorly at high temperature (David and Clavel 1969). Therefore, flies in Setouchi district move with increasing temperature.…”