Trait based functional and community ecology is en vogue. Most studies, however, ignore phenotypical diversity by characterizing entire species considering only trait means rather than their variability. Phenotypical variability may arise from genotypical differences or from ecological factors (e.g., nutritionally imbalanced diet), and these causes can usually not be separated in natural populations. We used a single genotype from a parthenogenetic model system (the oribatid mite Archegozetes longisetosus Aoki) to exclude genotypical differences. We investigated patterns of dietary (10 different food treatments) induced trait variation by measuring the response of nine different traits (relating to life history, morphology or exocrine gland chemistry). Nutritional quality (approximated by carbon-to-nitrogen ratios) influenced all trait means and their variation. Some traits were more prone to variation than others. Furthermore, the “threshold elemental ratio”- rule of element stoichiometry applied to phenotypic trait variation. Imbalanced food (i.e. food not able to fully meet the nutritional demands of an animal) led to lower trait mean values, but also to a higher variation of traits. Imbalanced food led not only to lower trait value averages, but also to higher trait variability. There was a negative relationship between both parameters, indicating a direct link of both, average trait levels and trait variation to nutritional quality. Hence, variation of trait means may be a predictor for general food quality, and further indicate trade-offs in specific traits an animal must deal with while feeding on imbalanced diets.

中文翻译：

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营养质量调节性状变异性

基于特征的功能和社区生态学正在流行。然而，大多数研究通过仅考虑性状手段而不是其变异性来表征整个物种而忽略了表型多样性。表型变异可能来自基因型差异或生态因素（例如营养不平衡的饮食），而这些原因通常在自然种群中无法分开。我们使用来自孤雌生殖模型系统（oribatid mite Archegozetes longisetosus Aoki）的单一基因型来排除基因型差异。我们通过测量九种不同性状（与生活史、形态学或外分泌腺化学有关）的反应来研究饮食模式（10 种不同的食物处理）诱导的性状变异。营养质量（近似于碳氮比）影响所有性状手段及其变异。有些性状比其他性状更容易发生变异。此外，“阈值元素比”——元素化学计量的规则适用于表型性状变异。不平衡的食物（即不能完全满足动物营养需求的食物）导致性状平均值较低，但也会导致性状变异较大。不平衡的食物不仅导致较低的平均性状值，而且还会导致较高的性状变异性。这两个参数之间存在负相关关系，表明平均性状水平和性状变异与营养质量之间存在直接联系。因此，性状平均值的变化可能是一般食品质量的预测指标，