High-fat and high-sugar diets induce rapid adaptations of fat storage in the house fly Musca domestica L

Dietary change can be a strong evolutionary force and lead to rapid
adaptation in organisms. High-fat and high-sugar diets can challenge key
metabolic pathways, negatively affecting other life-history traits and
inducing pathologies such as obesity and diabetes. In this study, we use
experimental evolution to investigate the plastic and evolutionary
responses to nutritionally unbalanced diets. We reared replicated lines of
larvae of the housefly Musca domestica on a fat-enriched (FAT), a
sugar-enriched (SUG), and a control (CTRL) diet for thirteen generations.
We measured development time in each generation, and larval growth and fat
accumulation in generations 1, 7, and 13. Subsequently, all lines were
reared for one generation on the control diet to detect any plastic and
evolutionary changes. In the first generation, time to pupation decreased
on a fat-rich diet and increased on a sugar-rich diet. The fat-rich diet
increased fat accumulation and, to a lesser extent, the dry weight of the
larvae. Multigenerational exposure to unbalanced diets caused compensatory
changes in development time, dry weight, as well as absolute and relative
fat content, although pattern and timing depended on diet and trait. When
put back on a control diet, many of the changes induced by the unbalanced
diets disappeared, indicating that the diet has large plastic effects.
Nevertheless, fat-evolved lines still grew significantly larger than the
sugar-evolved lines, and sugar-evolved lines had consistently lower fat
content. This can be an effect of parental diet or an evolutionary change
in nutrient metabolism as a consequence of multigenerational exposure to
unbalanced diets.

饮食改变可成为强有力的进化驱动力，并引发生物体的快速适应性演化。高脂与高糖饮食会对关键代谢通路造成应激挑战，负面影响其他生活史性状，并诱发肥胖、糖尿病等病理状态。本研究采用实验进化手段，探究生物体对营养失衡饮食的塑性响应与进化响应。我们将家蝇（Musca domestica）幼虫的重复品系分别饲养于高脂（FAT）、高糖（SUG）以及对照（CTRL）三种饮食环境中，持续繁育至第13代。我们测定了每一代的发育时长，并在第1、7、13代检测幼虫的生长情况与脂肪积累量。随后，将所有品系转移至对照饮食环境中饲养一代，以检测塑性与进化层面的变化。在第1代中，高脂饮食组的化蛹时长缩短，而高糖饮食组的化蛹时长则延长。高脂饮食可提升幼虫的脂肪积累量，并在较小程度上增加幼虫的干重。多代暴露于失衡饮食会引发发育时长、干重以及绝对与相对脂肪含量的代偿性变化，不过其变化模式与时间进程因饮食类型与性状类别而异。当将这些品系重新放回对照饮食环境时，失衡饮食诱导的多数变化均会消失，这表明饮食对生物体存在较强的塑性效应。尽管如此，高脂选育品系的幼虫仍显著大于高糖选育品系，且高糖选育品系的脂肪含量始终处于较低水平。该现象可能源于亲本饮食的影响，或是多代暴露于失衡饮食后营养代谢发生的进化改变。