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Title: Thirty years of tick molecular population genetic studies: a comprehensive review

Author
item ARAYA-ANCHETTA, ANA - Northern Arizona University
item BUSCH, JOSEPH - Northern Arizona University
item Scoles, Glen
item WAGNER, DAVID - Northern Arizona University

Submitted to: Infection, Genetics and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2014
Publication Date: 11/18/2014
Citation: Araya-Anchetta, A., Busch, J.D., Scoles, G.A., Wagner, D.M. 2014. Thirty years of tick molecular population genetic studies: a comprehensive review. Infection, Genetics and Evolution. 29:164-79.

Interpretive Summary: Population genetic studies can provide insights into the basic biology of arthropod disease vectors by estimating dispersal patterns and their potential to spread pathogens. In ticks, gene flow is closely related the movement of their hosts. However, other tick behaviors and life cycle strategies such as nest-dwelling behavior, the length of time spent feeding on a host, and host specificity can also have a large impact on population genetic structure. We have reviewed the literature on Tick population genetic studies done over the past 30 years in an effort to develope a conceptual framework for understanding tick population genetics in the context of their specialized biology. This review encompasses studies from 18 different tick species including representatives from the genera: Amblyomma, Dermacentor, Ixodes, Ornithodoros, and Rhipicephalus. Levels of population genetic structure ranged from none to very high and in eight species appeared to be determined primarily by the movement capacity of hosts, with low gene flow in tick species that use smaller less mobile hosts and high gene flow in ticks using highly mobile hosts. In nine other species, tick behaviorl limited gene flow and there was greater genetic structure than expected based upon host movement alone. In at least one case neither host movement nor tick behaviors could provide a satisfactory explanation for the observed levels of genetic structure. In this review we also discuss the strengths and limitations of different genetic markers and their applicability to ticks and suggest possible analyses when planning population genetic studies for ticks.

Technical Abstract: Population genetic studies provide insights into the basic biology of arthropod disease vectors by estimating dispersal patterns and their potential to spread pathogens. In wingless vectors, such as ticks, gene flow will be defined in large part by the mobility of their hosts. However, tick behaviors and life cycle strategies can limit their dispersal even on highly mobile hosts and lead to an increase in genetic structure. In this review we synthesize the published literature from three decades of tick population genetic studies. Based on studies from 21 tick species (including representatives from Amblyomma, Bothriocroton, Dermacentor, Ixodes, Ornithodoros, and Rhipicephalus), observed levels of population genetic structure in ticks varied from no structure to very high levels. In about half of the species (including representatives from Amblyomma, Bothriocroton, Dermacentor, and Ornithodoros), tick genetic structure appeared to be determined primarily by the movement capacity of hosts, with low gene flow observed in ticks that use smaller bodied less mobile hosts and high gene flow in ticks using highly mobile hosts. In a number of other species (primarily from Ixodes, Ornithodoros, and Rhipicephalus), behavioral limitations to gene flow appeared to result in greater genetic structure than expected based upon host movement capability alone. We also discuss the strengths and limitations of genetic markers and their applicability to ticks and suggest possible analyses when planning population genetic studies for ticks.