Various hypotheses have been proposed to explain mechanisms of personality formation. Several theoretical models predict that interactions between intrinsic state and behaviour gradually increase, or sometimes decrease, individual variation across ontogeny. However, these models should be empirically tested with a simple study system. Here, I investigated whether state differences in energy intake promote consistent behavioural differences in clonal geckos. I controlled food supply of two groups (high-energy or low-energy intake) and evaluated their life-history traits and behavioural traits throughout ontogeny. The high-energy group grew faster and laid eggs earlier than the low-energy group. Geckos at several age classes exhibited consistent individual differences in risk boldness, foraging boldness and activity. However, significant behavioural change was detected only in risk boldness; individuals in the high-energy group maintained boldness over their lifetimes, whereas individuals in the low-energy group changed to being shy at early stages and returned to being bold at later stages. These results imply that behaviours do not change gradually, but drastically, in response to energy intake, suggesting that personality formation does not represent simple divergence with ontogeny. Because predation risk and food availability change across an individual's lifetime, the state-dependent safety model could explain divergence and convergence of risk boldness in geckos at different life stages. The present study highlights the importance of a ‘life-stage specific’ effect of energy state on behaviour for personality formation.

中文翻译：

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在克隆壁虎物种的整个生命阶段，不同的食物量是否会逐渐促进个性变化？

已经提出了各种假设来解释人格形成的机制。一些理论模型预测，内在状态和行为之间的相互作用会逐渐增加或有时会减少个体发育过程中的个体差异。然而，这些模型应该用一个简单的研究系统进行经验测试。在这里，我调查了能量摄入的状态差异是否会促进克隆壁虎的行为差异。我控制了两组（高能量或低能量摄入）的食物供应，并评估了他们在整个个体发育过程中的生活史特征和行为特征。高能量组比低能量组生长更快，产卵更早。几个年龄段的壁虎在风险胆量、觅食胆量和活动方面表现出一致的个体差异。然而，仅在风险大胆中检测到显着的行为变化；高能量组的人一生都保持着大胆，而低能量组的人在早期变得害羞，在后期又恢复了大胆。这些结果意味着行为不会逐渐改变，而是会随着能量摄入而发生剧烈变化，这表明人格形成并不代表个体发育的简单分歧。由于捕食风险和食物供应在个体的一生中会发生变化，因此状态相关的安全模型可以解释壁虎在不同生命阶段的风险胆量的差异和趋同。本研究强调了能量状态对人格形成行为的“生命阶段特定”影响的重要性。