Disease exposure is a threat to all organisms, but there are a number of methods of self-defence. First, individuals can proactively prevent disease through avoidance behaviours. If they become infected, individuals can activate an immune response to control the infection. A trade-off between avoidance behaviours and immune response activation has been hypothesized to occur because of costs associated with each strategy. Individuals may balance behavioural and immunological strategies to provide optimal protection against disease. To test this hypothesis in a captive population of zebra finches, Taeniopygia guttata, we conducted behavioural trials to determine how much time focal birds associated with stimulus birds that were either healthy or displayed sickness behaviours. We then inoculated focal birds with lipopolysaccharide (LPS) and measured levels of natural antibodies, complement and haptoglobin. One physiological mechanism that may mediate the proposed trade-off between behavioural and immunological defences is the glucocorticoid hormone corticosterone (CORT). Therefore, we experimentally manipulated CORT in another subset of birds. Finally, it is unknown whether individuals are consistent in their strategy choice over time or whether strategy choice changes based on environmental context or life history stage. Thus, we tested behavioural and immunological responses multiple times. We found limited evidence that zebra finches trade off between behavioural avoidance and immune responses as protection against infection, instead these defences were unrelated or positively correlated in control birds. CORT changed the relationships between behavioural and immunological defences and these defences were traded-off after acute CORT exposure. Some behavioural and immunological defences were repeatable over three months. Thus, even though individuals may be consistent in behavioural and immunological defence strategies, these defences are not generally traded off. Further research is encouraged to determine whether behavioural and immunological trade-offs persist across contexts, life history stages, or in wild populations, and the degree to which strategies are influenced by selection.

中文翻译：

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对抗感染的可重复行为和免疫防御策略不会被权衡

疾病暴露对所有生物都是一种威胁，但有多种自卫方法。首先，个人可以通过回避行为主动预防疾病。如果他们被感染，个人可以激活免疫反应来控制感染。由于与每种策略相关的成本，已经假设发生回避行为和免疫反应激活之间的权衡。个人可以平衡行为和免疫策略，以提供最佳的疾病保护。为了在斑胸草雀的圈养种群 Taeniopygia guttata 中测试这一假设，我们进行了行为试验，以确定焦点鸟类与健康或表现出疾病行为的刺激鸟类相关的时间。然后我们用脂多糖 (LPS) 接种焦点鸟类并测量天然抗体、补体和结合珠蛋白的水平。糖皮质激素皮质酮 (CORT) 是一种可能介导行为防御和免疫防御之间建议权衡的生理机制。因此，我们在另一组鸟类中实验性地操纵了 CORT。最后，不知道个人的策略选择是否随着时间的推移保持一致，或者策略选择是否根据环境背景或生活史阶段发生变化。因此，我们多次测试了行为和免疫反应。我们发现斑胸草雀在行为回避和免疫反应之间权衡以防止感染的有限证据，相反，这些防御在对照鸟类中无关或正相关。CORT 改变了行为和免疫防御之间的关系，这些防御在急性 CORT 暴露后被权衡。一些行为和免疫防御在三个月内是可重复的。因此，即使个体在行为和免疫防御策略上可能是一致的，这些防御通常不会被权衡。鼓励进一步研究以确定行为和免疫学权衡是否在不同背景、生活史阶段或野生种群中持续存在，以及策略受选择影响的程度。尽管个体在行为和免疫防御策略上可能是一致的，但这些防御通常不会被权衡。鼓励进一步研究以确定行为和免疫学权衡是否在不同背景、生活史阶段或野生种群中持续存在，以及策略受选择影响的程度。尽管个体在行为和免疫防御策略上可能是一致的，但这些防御通常不会被权衡。鼓励进一步研究以确定行为和免疫学权衡是否在不同背景、生活史阶段或野生种群中持续存在，以及策略受选择影响的程度。