Interactive effects of sex, social environment, dietary restriction, and methionine on survival and reproduction in fruit flies

Abstract

For the evolution of life histories, the trade-off between survival and reproduction is fundamental. Because sexes optimize fitness in different ways, this trade-off is expected to be resolved differently by males and females. Consequently, the sexes are predicted to respond differently to changes in resource availability. In fruit flies, research on dietary restriction has focused largely on females maintained in the absence of males, thereby neglecting sexual interactions that affect reproductive behavior of both sexes under more natural conditions. Here, we tested for the interactive effects of diet (40, 60, 100, and 300 % of standard yeast concentrations) and social environment (separate-sex vs. mixed-sex groups) on male and female Drosophila melanogaster life histories. Additionally, we evaluated the essential amino acid methionine as an agent that can uncouple the survival-reproduction trade-off. We show sex differences in the effect of social environment on survival patterns, but not on reproductive fitness. In females, yeast had a positive effect on reproduction and a negative effect on survival. In males, yeast had a negative effect on reproduction and the effect on survival depended on the social environment. Methionine reduced survival, but had no effect on reproduction. Our findings highlight the need to include both sexes and to vary social environments in research programs aimed at lifespan extension and call for further evaluation of the fecundityrestoring effect of methionine.

Sex-specific effects of protein and carbohydrate intake on reproduction but not lifespan inDrosophila melanogaster

“…However, it is important to note that the lack of detectable costs in this study may reflect the fact that costs could lie in other unmeasured aspects of fly reproductive performance (i.e., offspring quality). Furthermore, at least one follow-up study has reported contrasting effects of methionine, showing that this amino acid reduced LS but had little effect on reproduction (Zajitschek et al ., 2013). …”

Feeding on frozen live yeast has some deleterious effects in Drosophila melanogaster

“…Indeed, it is now accepted that, the caloric content being constant, the proteins/carbohydrates ratio modulates lifespan, for instance in Drosophila melanogaster flies (e.g. Vigne and Frelin, 2007ab, Lee et al, 2008, Bruce et al, 2013, Zajitschek et al, 2013 and in mice (Solon-Biet et al, 2014). Therefore, the mainstream hypothesis to explain the positive effect of dietary restriction (DR) on lifespan, when observed, is now more subtle than it was, because it deals with the ratio of nutrients rather than simply with the number of calories.…”

“…Particularly, some authors have modified the protein:carbohydrate (P:C) ratio by restricting live yeast, a source of proteins (Chippindale et al, 1993, Le Bourg and Minois, 1996, Le Bourg and Le Rohellec, 2009, or by varying the quantity of amino acids (e.g. Zajitschek et al, 2013) or of dead yeast (e.g. Frelin, 2007ab, Zajitschek et al, 2013).…”

Amino Acids: Sensing and Implication into Aging

“…Supplementation with all kinds of amino acids or essential amino acids suppresses DR-promoted longevity. Methionine restriction also causes a slight decrease in the average lifespan without affecting reproductive fitness in Drosophila [54]. Thus, other amino acids have a role in lifespan regulation.…”