Conclusions
While Lyme disease is a major public health concern and prevalence has been increasing in the recent past, so has the incidence of many other tickborne diseases (R. J. Eisen & Eisen, 2018; Rosenberg et al., 2018). Understanding tick vectors, especially those like I. scapularis which transmits multiple human pathogens, is important not just in mitigating disease risk in humans, but to understanding these complex ecological systems in a OneHealth context. This model disease system has a complex taxonomic history and is intertwined with vector-host-pathogen-environmental relationships that still are not fully understood. The genetics of I. scapularis populations can be correlated with disease prevalence but a direct phenotype-genotype link had not yet been made. This study has built a foundation for tracking the genetic background, and the shifts in them, that are associated with higher disease transmission. Although the RAD loci investigated here illuminate overall patterns and potential candidate loci for further work, future whole genome resequencing studies ofI. scapularis individuals from populations across the geographic range are needed to obtain a more complete picture of genomic variability and characterization of candidate loci.
Identifying and monitoring genetic backgrounds associated with increased occurrence of tickborne disease can provide a rapid snapshot tool for assessing potential community risk. With this 3RAD approach, we identified genomic regions that should be further studied to determine how genetic diversity is related to behavioral differences among Northern and Southern populations. By using our 3RAD approach, we can examine consistent loci across the genome in many individual ticks, which can be replicated in new I. scapularis populations to continually add to this dataset. Having a database of trackable loci associated with increased Lyme disease risk or prevalence could allow public health officials to implement targeted, efficient, and thus cost-effective, control strategies for distinct tick populations or undertake public health awareness campaigns in at-risk communities before they become an emerging hotspot for tickborne disease.