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.生物体对变化环境做出可塑性响应的能力已得到充分研究。然而，尽管个体发育过程中的表型可塑性（phenotypic plasticity）是自然界表型变异的重要来源，但该过程中表型可塑性的变异情况却尚未得到充分阐释。本研究针对具有性二态性装饰结构的西部非洲慈鲷——带纹眶丽鱼（Pelvicachromis taeniatus），全面分析了其多性状形态学反捕食可塑性（antipredator plasticity）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两种不同感知捕食风险的环境中：一组施加同种告警信号（conspecific alarm cues），另一组以蒸馏水作为对照。形态学可塑性的表达随个体发育进程呈现显著差异：该可塑性最早在幼体早期便可观测到，此时暴露于告警信号环境中的实验鱼生长速度更快。随后直至性成熟前，均未观测到显著的可塑性响应。在性成熟节点，暴露于告警信号环境中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、尾柄更粗壮以及眼径更大。暴露于告警信号环境中的雄性个体，其性装饰结构的出现时间较对照组延迟。在成年后期，此类可塑性响应逐渐消退。尽管效应量较小，但此类响应被认为是适应性可塑性（adaptive plasticity）的潜在表现，因其可有效降低个体遭遇捕食的风险。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，表明表型可塑性的表达受到精细调控，可在个体发育的脆弱阶段及繁殖周期中增强防御能力，进而提升繁殖输出。