McCoy Karen D, Toty Céline, Dupraz Marlène, Tornos Jérémy, Gamble Amandine, Garnier Romain, Descamps Sébastien, Boulinier Thierry
MIVEGEC, Centre IRD, University of Montpellier CNRS IRD, Montpellier, France.
CEFE, UMR 5175, University of Montpellier CNRS, Montpellier, France.
Glob Chang Biol. 2023 Apr;29(7):1729-1740. doi: 10.1111/gcb.16617. Epub 2023 Feb 1.
Climate change is most strongly felt in the polar regions of the world, with significant impacts on the species that live there. The arrival of parasites and pathogens from more temperate areas may become a significant problem for these populations, but current observations of parasite presence often lack a historical reference of prior absence. Observations in the high Arctic of the seabird tick Ixodes uriae suggested that this species expanded poleward in the last two decades in relation to climate change. As this tick can have a direct impact on the breeding success of its seabird hosts and vectors several pathogens, including Lyme disease spirochaetes, understanding its invasion dynamics is essential for predicting its impact on polar seabird populations. Here, we use population genetic data and host serology to test the hypothesis that I. uriae recently expanded into Svalbard. Both black-legged kittiwakes (Rissa tridactyla) and thick-billed murres (Uria lomvia) were sampled for ticks and blood in Kongsfjorden, Spitsbergen. Ticks were genotyped using microsatellite markers and population genetic analyses were performed using data from 14 reference populations from across the tick's northern distribution. In contrast to predictions, the Spitsbergen population showed high genetic diversity and significant differentiation from reference populations, suggesting long-term isolation. Host serology also demonstrated a high exposure rate to Lyme disease spirochaetes (Bbsl). Targeted PCR and sequencing confirmed the presence of Borrelia garinii in a Spitsbergen tick, demonstrating the presence of Lyme disease bacteria in the high Arctic for the first time. Taken together, results contradict the notion that I. uriae has recently expanded into the high Arctic. Rather, this tick has likely been present for some time, maintaining relatively high population sizes and an endemic transmission cycle of Bbsl. Close future observations of population infestation/infection rates will now be necessary to relate epidemiological changes to ongoing climate modifications.
气候变化在世界极地地区感受最为强烈，对生活在那里的物种产生了重大影响。来自温带地区的寄生虫和病原体的到来可能会成为这些种群的一个重大问题，但目前对寄生虫存在情况的观察往往缺乏先前不存在的历史参考。对北极海鸟蜱I. uriae的高北极地区观察表明，在过去二十年中，该物种随着气候变化向极地扩展。由于这种蜱可直接影响其海鸟宿主的繁殖成功率，并传播包括莱姆病螺旋体在内的几种病原体，了解其入侵动态对于预测其对极地海鸟种群的影响至关重要。在这里，我们使用种群遗传数据和宿主血清学来检验I. uriae最近扩展到斯瓦尔巴群岛的假设。在斯匹次卑尔根的孔斯峡湾采集了黑脚三趾鸥（Rissa tridactyla）和厚嘴海鸦（Uria lomvia）的蜱和血液样本。使用微卫星标记对蜱进行基因分型，并使用来自蜱北部分布的14个参考种群的数据进行种群遗传分析。与预测相反，斯匹次卑尔根种群显示出高遗传多样性以及与参考种群的显著分化，表明长期隔离。宿主血清学也显示出对莱姆病螺旋体（Bbsl）的高暴露率。靶向PCR和测序证实了斯匹次卑尔根蜱中存在伯氏疏螺旋体，首次证明了高北极地区存在莱姆病菌。综合来看，结果与I. uriae最近扩展到高北极地区的观点相矛盾。相反，这种蜱可能已经存在了一段时间，维持着相对较高的种群数量以及Bbsl的地方传播周期。现在有必要对未来种群感染率进行密切观察，以便将流行病学变化与正在进行的气候改变联系起来。
