Grabow Marius, Mang Sirkka, Blaum Niels, Tiedemann Ralph, Radchuk Viktoriia, Kramer-Schadt Stephanie
Department of Ecological Dynamics, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
Institute of Ecology, Technische Universität Berlin, Berlin, Germany.
J Anim Ecol. 2025 Oct;94(10):1908-1921. doi: 10.1111/1365-2656.70106. Epub 2025 Jul 12.
Stressors that subtly yet persistently deplete energetic resources-such as heat, pollutants or parasites-are well studied in laboratory and clinical settings, where their physiological effects are often well understood, yet their influence on phenotypic and demographic traits in free-living populations remains critically understudied. A prominent example is pathogens and parasites that cause sublethal infections, often considered as relatively benign, particularly in species adapted to their presence. However, parasite-induced effects on phenotypic and demographic traits are often inconsistent, leaving researchers uncertain about their impact and whether they have meaningful fitness consequences. Here, we present a meta-analysis evaluating the effects of avian blood parasites (Plasmodium, Haemoproteus and Leucocytozoon), a widespread and cosmopolitan stressor, on songbird species. Through a systematic review of 2473 publications, we identified 35 studies spanning 51 species and extracted 172 relevant effect sizes assessing host condition, phenology, reproduction and survival. Our findings reveal consistent negative impacts: reductions in body condition, reproductive success and survival, along with delays in phenological events such as breeding. Furthermore, our findings revealed a critical research gap: despite the widespread study of avian blood parasites, only a limited number provide suitable effect sizes for assessing parasite impacts on demographic traits-let alone behavioural traits. This scarcity of data highlights the urgent need to understand pathogen-induced effects on animal behaviour and demography, especially in the face of accelerating global change. We advocate for an integrative approach, combining behavioural, phenotypic, and demographic traits, to uncover the cascading consequences of parasitic infections on wild populations.
在实验室和临床环境中，对那些能微妙却持续消耗能量资源的应激源（如高温、污染物或寄生虫）已有充分研究，在这些环境中，它们的生理效应通常已为人熟知，但它们对自由生活种群的表型和人口统计学特征的影响仍严重缺乏研究。一个突出的例子是导致亚致死感染的病原体和寄生虫，它们通常被认为相对无害，尤其是在适应其存在的物种中。然而，寄生虫对表型和人口统计学特征的影响往往不一致，这让研究人员对其影响以及它们是否具有有意义的适合度后果感到不确定。在此，我们进行了一项荟萃分析，评估鸟类血液寄生虫（疟原虫、血变原虫和白细胞虫）这一广泛存在且分布于世界各地的应激源对鸣禽物种的影响。通过对2473篇出版物的系统综述，我们确定了涵盖51个物种的35项研究，并提取了172个相关效应量，以评估宿主状况、物候、繁殖和生存情况。我们的研究结果揭示了一致的负面影响：身体状况、繁殖成功率和生存率下降，以及诸如繁殖等物候事件的延迟。此外，我们的研究结果还揭示了一个关键的研究空白：尽管对鸟类血液寄生虫进行了广泛研究，但只有少数研究提供了适合评估寄生虫对人口统计学特征影响的效应量，更不用说行为特征了。数据的稀缺凸显了迫切需要了解病原体对动物行为和人口统计学的影响，尤其是在面对加速的全球变化时。我们主张采用一种综合方法，将行为、表型和人口统计学特征结合起来，以揭示寄生虫感染对野生种群的连锁后果。
