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.生物对环境变化产生可塑性响应的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，但人们对其的理解仍较为匮乏。本研究针对带有性二态装饰特征的西非慈鲷带纹矛耙丽鱼（Pelvicachromis taeniatus），全面分析了其多性状形态学反捕食可塑性的个体发育变异。本研究采用分窝实验设计（split-clutch design），将实验鱼饲养于不同强度的模拟捕食风险环境中：处理组施加同种告警信号（conspecific alarm cues），对照组则添加蒸馏水。研究结果显示，形态学可塑性随个体发育进程呈现显著差异：该可塑性最早在幼龄阶段即可被观测到，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，均未检测到显著的可塑性响应。在性成熟节点，暴露于告警信号的雄性个体体型大于对照组雄性，具体表现为躯体更深、背鳍棘更长、尾柄（caudal peduncle）更粗壮以及眼径更大。暴露于告警信号的雄性个体，其性装饰特征的出现时间较对照组延迟。进入成年后期后，上述可塑性响应逐渐消退。尽管各响应的效应量较小，但这些响应被认为是适应性可塑性的潜在表现，因为它们有望降低个体被捕食的风险。而在雌性个体中，未观测到任何可塑性响应。本研究结果与理论预期相符，表明可塑性的表达受到精细调控，这可能会在个体发育的脆弱阶段提升防御能力，并最终提升繁殖产出。