Fitness outcomes in relation to individual variation in constitutive innate immune function

Although crucial for host survival when facing persistent parasite pressure, costly immune functions will inevitably compete for resources with other energetically expensive traits such as reproduction. Optimising, but not necessarily maximising, immune function might therefore provide net benefit to overall host fitness. Evidence for associations between fitness and immune function is relatively rare, limiting our potential to understand ultimate fitness costs of immune investment. Here, we assess how measures of constitutive immune function (haptoglobin, natural antibodies, complement activity) relate to subsequent fitness outcomes (survival, reproductive success, dominance acquisition) in a wild passerine (Malurus coronatus). Surprisingly, survival probability was not positively linearly predicted by any immune index. Instead, both low and high values of complement activity (quadratic effect) were associated with higher survival, suggesting that different immune investment strategies...

尽管在面对持续寄生虫压力时对宿主生存至关重要，但代价高昂的免疫功能不可避免地会与繁殖等其他能量消耗大的性状竞争资源。因此，优化（而非必然最大化）免疫功能可能为宿主整体适应性带来净收益。适应性与免疫功能之间关联的证据相对稀缺，限制了我们理解免疫投资最终适应性代价的潜力。在此，我们评估了野生雀形目鸟类紫冠细尾鹩莺（Malurus coronatus）的组成型免疫功能（constitutive immune function）指标（触珠蛋白（haptoglobin）、天然抗体（natural antibodies）、补体活性（complement activity））与后续适应性结果（生存、繁殖成功率、优势地位获得）之间的关系。令人惊讶的是，任何免疫指标均未对生存概率产生正向线性预测。相反，补体活性的低值和高值（二次效应）均与更高的生存率相关，这表明不同的免疫投资策略...