Data from: Pale and dark morphs of tawny owls show different patterns of telomere dynamics in relation to disease status

Parasites are expected to exert long-term costs on host fecundity and longevity. Understanding the consequences of heritable polymorphic variation in disease defence in wild populations is essential in order to predict evolutionary responses to changes in disease risk. Telomeres have been found to shorten faster in malaria-diseased individuals compared with healthy ones with negative effects on longevity and thereby fitness. Here, we study the impact of haemosporidian blood parasites on telomere dynamics in tawny owls, which display a highly heritable plumage colour polymorphism. Previously, it has been shown that blood parasites have morph-specific impact on body mass maintenance. Here, we show that telomeres shortened faster in individuals with shorter breeding lifespan. Telomere length was negatively associated with the degree of pheomelanic brown coloration and shorter in infected than uninfected individuals. The rate of telomere shortening between breeding seasons was faster in darker pheomelanic individuals and suppression of parasite intensity between seasons was associated with faster telomere shortening in the paler individuals but not in darker ones. We propose that morph-specific physiological profiles cause differential telomere shortening and that this is likely to be a mechanism involved in previously documented environment-driven survival selection against the pheomelanic morph in this population.

寄生虫被认为会对宿主的繁殖能力和寿命造成长期的适应性代价。要预测野生种群面对疾病风险变化时的演化响应，解析疾病防御相关的可遗传多态变异所带来的后果至关重要。端粒（Telomeres）的缩短速度在疟疾感染个体中显著快于健康个体，该现象会对宿主寿命乃至适合度（fitness）产生负面影响。本研究以具有高度可遗传羽色多态性（plumage colour polymorphism）的灰林鸮（tawny owls）为研究对象，探究血孢子虫（haemosporidian）血液寄生虫对其端粒动态变化的影响。此前已有研究表明，血液寄生虫对灰林鸮的体重维持存在形态型特异性（morph-specific）影响。本研究发现，繁殖寿命更短的个体端粒缩短速度更快。端粒长度与褐黑素（pheomelanic）介导的棕褐色羽色程度呈负相关，且感染寄生虫的个体端粒长度显著短于未感染个体。繁殖季间的端粒缩短速率在褐黑素羽色更深的个体中更快；而季间寄生虫载量的抑制仅在羽色更浅的个体中与端粒更快缩短相关，在羽色更深的个体中则无此关联。我们提出，不同形态型个体的特异性生理特征会导致端粒缩短速率出现差异，而该机制可能正是此前该种群中被观测到的、由环境驱动的针对褐黑素羽色形态型的生存选择所涉及的潜在机制。