Poli et al.
Strong genetic structure among populations of the tick Ixodes ricinus across its range.
Ticks Tick Borne Dis. 2020, in press, doi.org/10.1016/j.ttbdis.2020.101509
Despite the threats of the widely distributed tick Ixodes ricinus, there is so far little known about the genetic structure of tick populations across its entire species range. Differences in the genetic population and its spatial distribution can impact the fitness of the tick in various regions, its questing behavior, host range for sucking blood, the prevalence for certain pathogens etc. The authors have analyzed the population genetic structure of I. ricinus based on single nucleotide polymorphisms. A total of 597 individuals from 28 tick populations sampled in 20 countries across Europe, the Middle East, Asia, and northern Africa were elucidated. A strong divergence between northern African and Eurasian populations was found, but also two genetic European clusters, and an association was suggested between the geographical locations and the genetic structure of tick populations, e.g. a clear differentiation was found between ticks from southern and northern European populations. All samples from northern Africa have the same ancestry and no samples from northern Africa share ancestry with those across Eurasia. Surprisingly, a close genetic affinity between all Atlantic samples (e.g. Ireland, England, France, Spain) and the geographically separated populations from Turkey and Iran was identified. Local adaption could impact the spatial redistribution of the species range in response to changes in abiotic conditions. Ticks from a given genetic cluster could be prone to increase in abundance in some regions which could also have influence on the pathogen population.