Data_Sheet_1_Oxidative Damage Is Influenced by Diet But Unaffected by Selection for Early Age of Oviposition in the Marula Fly, Ceratitis cosyra (Diptera: Tephritidae).docx

The expression of life-history traits, such as lifespan or reproductive effort, is tightly correlated with the amount and blend of macronutrients that individuals consume. In a range of herbivorous insects, consuming high protein to carbohydrate ratios (P:C) decreases lifespan but increases female fecundity. In other words, females face a resource-based trade-off between lifespan and fecundity. Redox metabolism may help mediate this trade-off, if oxidative damage is elevated by reproductive investment and if this damage, in turn, reduces lifespan. Here, we test how diets varying in P:C ratio affect oxidative damage and antioxidant protection in female and male of the marula fly, Ceratitis cosyra (Diptera: Tephritidae). We use replicated lines that have been subjected to experimental evolution and differ in their lifespan and reproductive scheduling. We predicted that high fecundity would be associated with high oxidative damage and reduced antioxidant defences, while longer lived flies would show reduced damage and elevated antioxidant defences. However, higher levels of oxidative damage were observed in long-lived control lines than selection lines, but only when fed the diet promoting lifespan. Flies fed diets promoting female fecundity (1:4 and 1:2 P:C) suffered greater oxidative damage to lipids than flies fed the best diet (0:1 P:C) for lifespan. Total antioxidant capacity was not affected by the selection regime or nutrition. Our results reiterate the importance of nutrition in affecting life-history traits, but suggest that in C. cosyra, reactive oxygen species play a minimal role in mediating dietary trade-offs between lifespan and reproduction.

生命史性状（如寿命或繁殖投入）的表达，与个体摄入的宏量营养素的总量及配比紧密相关。在多种植食性昆虫中，摄入高蛋白质与碳水化合物比值（P:C）的食物会缩短寿命，但提升雌性繁殖力。换言之，雌性个体面临着基于资源分配的寿命与繁殖力之间的权衡。若繁殖投入会加剧氧化损伤，且该损伤反过来又会缩短寿命，那么氧化还原代谢或可介导这一权衡过程。本研究中，我们探究了不同P:C比值的日粮对马鲁拉实蝇（Ceratitis cosyra，双翅目：实蝇科）雌雄个体的氧化损伤与抗氧化保护能力的影响。我们采用经过实验进化处理的重复选育系，这些品系在寿命与繁殖节律上存在差异。我们提出如下假设：高繁殖力将伴随高水平的氧化损伤与抗氧化防御能力的下降，而长寿命实蝇则会表现出更低的氧化损伤与更高的抗氧化防御能力。然而，仅在喂食可延长寿命的日粮时，长寿命对照品系的氧化损伤水平才高于选育品系。喂食可提升雌性繁殖力的日粮（P:C为1:4与1:2）的实蝇，其脂质氧化损伤程度高于喂食最适寿命日粮（P:C为0:1）的个体。总抗氧化能力不受选育体系与日粮营养的影响。本研究结果再次证实了营养对生命史性状的重要影响，但同时表明，在C. cosyra中，活性氧（reactive oxygen species）在介导寿命与繁殖之间的日粮权衡过程中仅发挥极小的作用。