Harnessing 50 years of tick population genetics: Choosing the right molecular tool for contemporary research.

Ticks are ectoparasites of major medical, veterinary and ecological importance, transmitting a wide range of pathogens to humans, companion animals and livestock. Understanding the population structure of ticks is essential for uncovering patterns of pathogen transmission, and population genetics provides a powerful method for this purpose. Tick population studies are uniquely challenging as their biology is shaped by complex interactions between hosts, microbiome and environmental factors. The choice of population genetic tools is crucial, as different methods offer varying levels of cost, throughput, resolution and accessibility, which can significantly influence the quality and scope of results. This review traces the evolution of molecular tools in tick population genetics, from early allozyme electrophoresis in the 1970s to advanced whole genome sequencing (WGS) technologies. It critically evaluates key methodologies, including allozyme electrophoresis, random amplified polymorphic DNA (RAPD), microsatellites (STRs), amplified fragment length polymorphisms (AFLP), sequence typing, restriction-site associated DNA sequencing (RADseq) and WGS, highlighting their strengths, limitations and applications. By offering a practical guide to these tools, this review helps researchers select the most appropriate methods for their studies and allows interpretation of results from older tools in the context of modern research. Sequence typing and RADseq currently provide the best balance of cost and practicality, while WGS has great potential once sequencing costs decline. This resource empowers researchers to make informed decisions, maximise the impact of their work and gain deeper insights into disease vector population structure.