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Phylogeography of the blacklegged tick Ixodes scapularis throughout the United States identifies candidate loci for differences in vectorial capacity
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  • Julia Frederick,
  • Alec Thompson,
  • Prisha Sharma,
  • Guha Dharmarajan,
  • Isobel Ronai,
  • Risa Pesapane,
  • Ryan Smith,
  • Kellee Sundstrom,
  • Jean Tsao,
  • Holly Tuten,
  • Michael J. Yabsley,
  • Travis Glenn
Julia Frederick
University of Georgia

Corresponding Author:[email protected]

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Alec Thompson
University of Georgia
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Prisha Sharma
University of Georgia
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Guha Dharmarajan
University of Georgia
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Isobel Ronai
Harvard University
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Risa Pesapane
The Ohio State University
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Ryan Smith
Iowa State University
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Kellee Sundstrom
Oklahoma State University
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Jean Tsao
Michigan State University
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Holly Tuten
University of Illinois Urbana-Champaign
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Michael J. Yabsley
University of Georgia
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Travis Glenn
University of Georgia
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The blacklegged tick, Ixodes scapularis, is a vector of Borrelia burgdorferi sensu stricto (s.s.), the causative agent of Lyme disease, part of a slow-moving epidemic of Lyme borreliosis spreading across the northern hemisphere. There are well-known geographic differences in the vectorial capacity of these ticks associated with genetic variation. Despite the need for detailed genetic information in this disease system, previous phylogeographic studies of these ticks have been restricted to relatively few populations or genetic loci. Here we present the most comprehensive phylogeographic study of I. scapularis conducted by using 3RAD and surveying 353 ticks from 33 counties throughout the range of I. scapularis. We found limited genetic variation among populations from the Northeast and Upper Midwest, where Lyme disease is most common, and higher genetic variation among populations from the South. We identify four genetic clusters of I. scapularis that are consistent with four major geographic regions, plus a distinct Central Florida group. In regions where Lyme disease is increasing in frequency, the I. scapularis populations genetically group with ticks from historically highly Lyme-endemic regions. Finally, we identify ten variable DNA sites that contribute the most to population differentiation. These variable sites cluster on one of the chromosome-scale scaffolds for I. scapularis and are within identified genes. Our findings illuminate the need for additional research to identify loci causing variation in the vectorial capacity of I. scapularis and where additional tick sampling would be most valuable to further understand disease trends caused by pathogens transmitted by I. scapularis.
22 Aug 2022Submitted to Molecular Ecology
23 Aug 2022Submission Checks Completed
23 Aug 2022Assigned to Editor
30 Aug 2022Reviewer(s) Assigned
07 Dec 2022Review(s) Completed, Editorial Evaluation Pending
08 Dec 2022Editorial Decision: Revise Minor
19 Feb 20231st Revision Received
27 Feb 2023Submission Checks Completed
27 Feb 2023Assigned to Editor
27 Feb 2023Review(s) Completed, Editorial Evaluation Pending
08 Mar 2023Editorial Decision: Accept