Express yourself: bold individuals induce enhanced morphological defences

Organisms display an impressive array of defence strategies in nature. Inducible defences (changes in morphology and/or behaviour within a prey's lifetime) allow prey to decrease vulnerability to predators and avoid unnecessary costs of expression. Many studies report considerable interindividual variation in the degree to which inducible defences are expressed, yet what underlies this variation is poorly understood. Here, we show that individuals differing in a key personality trait also differ in the magnitude of morphological defence expression. Crucian carp showing risky behaviours (bold individuals) expressed a significantly greater morphological defence response when exposed to a natural enemy when compared with shy individuals. Furthermore, we show that fish of different personality types differ in their behavioural plasticity, with shy fish exhibiting greater absolute plasticity than bold fish. Our data suggest that individuals with bold personalities may be able to compensate for their risk-prone behavioural type by expressing enhanced morphological defences.

自然界中，生物演化出了种类繁多的防御策略。诱导防御（inducible defences）指猎物在其生命周期内发生的形态或行为改变，可帮助猎物降低被捕食者攻击的脆弱性，同时避免防御表达所产生的不必要成本。诸多研究表明，个体间在诱导防御的表达程度上存在显著差异，但该差异背后的驱动机制仍不甚明晰。本研究发现，具有关键人格特质差异的个体，其形态防御的表达强度也存在显著差异。与表现出谨慎行为的害羞型个体相比，表现出冒险行为的大胆型鲫（Crucian carp）在暴露于天敌时，其形态防御反应的强度显著更高。此外，本研究还证实，不同人格类型的鱼类其行为可塑性存在差异，害羞型个体的绝对行为可塑性要高于大胆型个体。我们的研究数据表明，具有大胆人格特质的个体或许可通过增强形态防御的表达，来弥补自身冒险型行为模式所带来的生存风险。