Data from: Dietary-based developmental plasticity affects juvenile survival in an aquatic detritivore

Developmental plasticity is ubiquitous in natural populations, but the underlying causes and fitness consequences are poorly understood. For consumers, nutritional variation of juvenile diets is likely associated with plasticity in developmental rates, but little is known about how diet quality can affect phenotypic trajectories in ways that might influence survival to maturity and lifetime reproductive output. Here, we tested how the diet quality a freshwater detritivorous isopod (Asellus aquaticus), in terms of elemental ratios of diet (i.e. carbon : nitrogen : phosphorus; C :N: P), can affect (i) developmental rates of body size and pigmentation and (ii) variation in juvenile survival. We reared 1047 individuals, in a full-sib split family design (29 families), on either a high (low C : P, C :N) or low quality (high C : P, C : N), and quantified developmental trajectories of body size and pigmentation for every individual over 12 weeks. Our diet contrast caused strong divergence in the developmental rates of pigmentation but not growth, culminating in a distribution of adult pigmentation spanning the broad range of phenotypes observed both within and among natural populations. Under low-quality diet, we found highest survival at intermediate growth and pigmentation rates. By contrast, survival under high-quality diet survival increased continuously with pigmentation rate, with longest lifespans at intermediate growth rates and high pigmentation rates. Building on previous work which suggests that visual predation mediates the evolution of cryptic pigmentation in A. aquaticus, our study shows how diet quality and composition can generate substantial phenotypic variation by affecting rates of growth and pigmentation during development in the absence of predation.

发育可塑性在自然种群中广泛存在，但其内在驱动机制与适合度效应迄今仍未得到充分阐释。对于取食者而言，幼体日粮的营养变异大概率与发育速率的可塑性相关，但目前对于日粮质量如何通过影响个体存活至性成熟的概率以及终生繁殖产出的路径来塑造表型轨迹，仍知之甚少。本研究以淡水腐食性等足类（水虱，Asellus aquaticus）为对象，以日粮元素比例（即碳:氮:磷；C:N:P）为衡量指标，探究日粮质量如何影响（i）个体体型与体色的发育速率，以及（ii）幼体存活率的变异。我们采用全同胞拆分家系设计（共29个家系），饲养了1047个个体，分别饲喂高质量日粮（低C:P、C:N比）与低质量日粮（高C:P、C:N比），并在12周内对每一个体的体型与体色发育轨迹进行量化测定。日粮处理的差异显著改变了体色发育速率，但对生长速率无明显影响，最终使得成虫体色的分布覆盖了自然种群内部及种群间所观测到的广泛表型范围。在低质量日粮组中，中等生长速率与中等体色发育速率的个体存活率最高；而在高质量日粮组中，存活率随体色发育速率持续升高，且在中等生长速率与高体色发育速率的个体中寿命最长。基于此前提出的视觉捕食介导水虱（A. aquaticus）隐蔽体色演化的研究结论，本研究阐明了在无捕食压力的条件下，日粮质量与组成可通过调控发育阶段的生长与体色发育速率，进而产生显著的表型变异。