Data from: Canalisation in the wild: effects of developmental conditions on physiological traits are inversely linked to their association with fitness

Ecological conditions affect fitness, but mechanisms causing such effects are not well known, while evolved responses to environmental variation may depend on the underlying mechanisms. Consequences of environmental conditions vary strongly between traits, but a framework to interpret such variation is lacking. We propose that variation in trait response may be explained by differential canalisation, with traits with larger fitness effects showing weaker responses to environmental perturbations due to preferential resource allocation to such traits. We tested the canalisation hypothesis using brood size manipulation in wild jackdaw nestlings in which we measured eight physiological traits (mainly oxidative stress markers), and two feather traits. For each trait, we estimated manipulation response and association with fitness (over-winter survival). As predicted, a strong negative correlation emerged between manipulation response and association with fitness (r=-0.76). We discuss the consequences of differential trait canalization for the study of mechanisms mediating environmental effects on fitness.

生态条件会影响适合度（fitness），但介导此类影响的具体机制仍未被阐明；而生物对环境变异的演化响应，可能依赖于这些潜在的作用机制。环境条件对不同性状的影响存在显著差异，但目前仍缺乏可用于阐释此类差异的统一理论框架。我们提出，性状响应的差异可通过差异化渠化（canalisation）得到阐释：由于生物会优先为对适合度影响更大的性状分配资源，这类性状对环境扰动的响应强度相对更弱。我们以野生寒鸦雏鸟为研究对象，通过窝雏数操控（brood size manipulation）实验对该渠化假说进行了验证，实验过程中测定了8项生理性状（主要为氧化应激标志物）与2项羽毛性状。针对每一项性状，我们分别估算了其对窝雏数操控的响应强度，以及该性状与适合度的关联（以越冬存活率作为适合度的衡量标准）。正如实验预期，性状对窝雏数操控的响应强度与其和适合度的关联程度之间呈现出显著负相关（相关系数r=-0.76）。我们还探讨了性状差异化渠化对"环境影响适合度的介导机制"相关研究的潜在影响与意义。