Climate change in the Arctic: testing the poleward expansion of ticks and tick-borne diseases - Immunological data and analyses
Karen D. McCoy1,2, Céline Toty2, Marlène Dupraz2, Jérémy Tornos2,3, Amandine Gamble3, Romain Garnier3, Sébastien Descamps4, Thierry Boulinier3
1 Montpellier Ecology and Evolution of Disease Network (MEEDiN), Montpellier, France
2 MIVEGEC, University of Montpellier CNRS IRD, Centre IRD, Montpellier, France
3 CEFE UMR 5175 University of Montpellier CNRS, 34294 Montpellier, France
4 Norwegian Polar Institute, Fram Centre, Tromsø, Norway
Article corresponding author: karen.mccoy@ird.fr
Serological dataset and analysis corresponding author: amandine.gamble@gmail.com
This repository accompanies the article "Climate change in the Arctic: testing the poleward expansion of ticks and tick-borne diseases" (McCoy et al. 2022). It focuses on immunological data and analysis only. Statistical results and plots are presented this R notebook. The code for reproducing the statistical analyses and recreating associated display figures is also included in this repository.
If you use the code or data provided here, please make sure to cite our work as below:
McCoy et al. 2022. Climate change in the Arctic: testing the poleward expansion of ticks and tick-borne diseases.
Bibtex record:
@electronic{mccoy2022climate,
Author = {
Karen D. McCoy AND
Céline Toty AND
Marlène Dupraz AND
Jérémy Tornos AND
Amandine Gamble AND
Romain Garnier AND
Sébastien Descamps AND
Thierry Boulinier},
Title = {Climate change in the Arctic: testing the poleward expansion of ticks and tick-borne diseases},
Date = {2022},
URL = {}
}
Climate change is most strongly felt in the polar regions of the world, with significant impacts for the species that live in these extreme environments. 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may become a significant problem for these populations, but current observations of parasite presence often lack a historical reference of prior absence.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 recently expanded its range northward. As this tick can have a direct impact on the breeding success of its seabird hosts and is vector of many potential disease agents, including Lyme disease spirochaetes, its presence and origin are important elements for predicting its impact on polar seabird populations. Here, we use population genetic data and host serology to test the hypothesis that Ixodes uriae has recently expanded into the Svalbard archipelago. Both Black-legged kittiwakes (Rissa tridactyla) and Thick-billed murres (Uria lomvia) were captured in Kongsfjorden, Spitsbergen and sampled for ticks and blood. Collected ticks were genotyped using microsatellite markers and population genetic analyses were carried out using data from 14 additional seabird colonies distributed across the tick’s northern distribution. In contrast to predictions based on a recent expansion, the Spitsbergen population showed high genetic diversity and significant differentiation from the more southern populations, suggesting long-term population isolation. Host serology also demonstrated a high exposure rate to Lyme disease spirochaetes (Bbsl). Targeted PCR on tick DNA extracts and sequencing identified the presence of Borrelia garinii in a Spitsbergen tick, confirming seabird exposure and demonstrating for the first time that Lyme disease bacteria are present in the high Arctic. Taken together, results contradict the notion that Ixodes uriae has recently expanded into the high Arctic region. Rather, this tick has likely been present for some time, maintaining relatively high population sizes and an endemic transmission cycle of Bbsl spirochaetes. Close future observations on population infestation/infection rates will now be necessary to relate epidemiological changes to ongoing climate modifications.