Data from: The plastic fly: the effect of sustained fluctuations in adult food supply on life history traits

Many adult traits in Drosophila melanogaster show phenotypic plasticity, and the effects of diet on traits such as lifespan and reproduction are well explored. Although plasticity in response to food is still present in older flies, it is unknown how sustained environmental variation affects life-history traits. Here, we explore how such life-long fluctuations of food supply affect weight and survival in groups of flies and affect weight, survival and reproduction in individual flies. In both experiments, we kept adults on constant high or low food and compared these to flies that experienced fluctuations of food either once or twice a week. For these ‘yoyo’ groups, the initial food level and the duration of the dietary variation differed during adulthood, creating four ‘yoyo’ fly groups. In groups of flies, survival and weight were affected by adult food. However, for individuals, survival and reproduction, but not weight, were affected by adult food, indicating that single and group housing of female flies affects life-history trajectories. Remarkably, both the manner and extent to which life-history traits varied in relation to food depended on whether flies initially experienced high or low food after eclosion. We therefore conclude that the expression of life-history traits in adult life is affected not only by adult plasticity, but also by early adult life experiences. This is an important but often overlooked factor in studies of life-history evolution and may explain variation in life-history experiments.

黑腹果蝇（Drosophila melanogaster）的诸多成年性状均表现出表型可塑性（phenotypic plasticity），而饮食对寿命、繁殖等性状的影响已得到充分研究。尽管高龄果蝇仍存在对食物的可塑性响应，但持续的环境变化如何影响生活史性状（life-history traits）仍未明确。本研究探讨终生食物供应波动如何影响种群果蝇的体重与存活情况，以及个体果蝇的体重、存活与繁殖能力。两项实验中，我们将成年果蝇饲养于恒定高/低食物环境中，并与每周经历1次或2次食物波动的果蝇进行对照。对于这些“悠悠球”实验组，其初始食物水平与成年期饮食变化的时长存在差异，由此形成4组“悠悠球”果蝇实验组。种群水平下，果蝇的存活与体重受成年期食物条件影响；但个体层面上，存活与繁殖能力受成年期食物条件影响，而体重不受此影响，这表明雌性果蝇的单只饲养与群居饲养会改变其生活史轨迹。值得注意的是，生活史性状随食物条件变化的方式与幅度，均取决于果蝇羽化（eclosion）后初始的食物环境是高还是低。因此我们得出结论：成年果蝇的生活史性状表达不仅受成年期的可塑性影响，还受到成虫早期生活经历的调控。这是生活史进化研究中一项重要却常被忽视的因素，或可解释不同生活史实验间的结果差异。