Data from: Neglected patterns of variation in phenotypic plasticity: age- and sex-specific antipredator plasticity in a cichlid fish

The ability of organisms to plastically respond to changing environments is well studied. However, variation in phenotypic plasticity during ontogeny is less well understood despite its relevance of being an important source of phenotypic variation in nature. Here, we comprehensively study ontogenetic variation in morphological antipredator plasticity across multiple traits in Pelvicachromis taeniatus, a Western African cichlid fish with sexually dimorphic ornamentation. In a split-clutch design, fish were raised under different levels of perceived predation risk (conspecific alarm cues or distilled water). Morphological plasticity varied substantially across ontogeny: it was first observable at an early juvenile stage where alarm cue-exposed fish grew faster. Subsequently, significant plasticity was absent until the onset of sexual maturity. Here, alarm-cue-exposed males were bigger than control males, which led to deeper bodies, longer dorsal spines, bigger caudal
peduncles and increased eye diameters. Sexual ornamentation emerged delayed in alarm cue-exposed males. In later adulthood, the plastic responses receded. Despite small effect sizes, these responses represent putative adaptive plasticity as they are likely to reduce predation risk. In females, we did not observe any plasticity. In accordance with theory, these results suggest fine-tuned expression of plasticity that potentially increases defenses during vulnerable developmental stages and reproductive output.

生物体响应环境变化的可塑性能力已得到广泛研究。然而，尽管个体发育（ontogeny）过程中的表型可塑性（phenotypic plasticity）变异是自然界表型变异的重要来源，但学界对其的认知仍较为有限。本研究以具有性二态装饰的西非慈鲷Pelvicachromis taeniatus为研究对象，全面探究其多性状形态学反捕食表型可塑性的个体发育变异。本研究采用分窝实验设计（split-clutch design），将实验鱼分别饲养于不同感知捕食风险水平的环境中：即暴露于同种告警信号（conspecific alarm cues），或置于蒸馏水对照组。研究结果显示，形态学表型可塑性随个体发育进程呈现显著差异：最早可在早期幼体阶段观测到该可塑性——此时暴露于告警信号的幼鱼生长速度更快。在此之后，直至性成熟前，均未观测到显著的表型可塑性；直至性成熟阶段，暴露于告警信号的雄性个体体型显著大于对照组雄性，进而表现出躯体更深、背鳍棘更长、尾柄更粗壮以及眼径更大的特征。暴露于告警信号的雄性个体的性装饰性状出现时间延迟。在成年后期，该可塑性响应逐渐消退。尽管效应量（effect size）较小，但这些响应属于推定的适应性表型可塑性，因为它们有望降低个体遭遇捕食的风险。而在雌性个体中，未观测到任何表型可塑性。本研究结果符合相关理论预测，表明表型可塑性的表达受到精细调控：其可在个体发育的脆弱阶段增强防御能力，并提升繁殖产出。