Term of Award

Summer 2023

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biology

Committee Chair

Lorenza Beati

Committee Member 1

Joshua Gibson

Committee Member 2

Scott Harrison

Committee Member 3

Christopher Paddock

Committee Member 3 Email



The Gulf Coast tick, Amblyomma maculatum Koch, 1844 is widespread throughout North and Central America and is the primary vector for the emerging pathogen Rickettsia parkeri. In the U.S., the population in the Southwest (A. maculatum morphotype III) is morphologically different from the population east of the Rocky Mountains (A. maculatum morphotype II). This research tests the hypothesis that A. maculatum morphotype II and morphotype III represent distinct species through the analysis and comparison of 6 microsatellite loci and suite of 135,221 Single nucleotide polymorphisms (SNPs) generated from ddRADseq. Population genetic analysis of both microsatellites and SNPs reveals very strong genetic isolation between morphotype II and morphotype III with virtually nonexistent gene flow between the two populations. Given this and previous studies investigating the relationship between morphotypes II and III, morphotype III should be elevated to the species level under an integrative species concept. Within morphotype II, the subpopulation sampled in Texas displayed strong differentiation compared to other Eastern sites but further study is warranted to determine its relationship to the rest of the A. maculatum group. Between other Eastern subpopulations there was low to moderate differentiation with no isolation by distance, consistent with long-distance dispersal facilitated primarily by movement on migrating birds. Microsatellites and SNPs were equivalent in their assessment of genetic differentiation, though SNPs had much greater precision and possessed a clearer ability to cluster distinct groups by discriminate analysis of principal components.

Research Data and Supplementary Material


Supplementary_A.csv (10336 kB)
Allelic Richness SNPs

Supplementary_B.csv (5405 kB)
Number of individuals per Population with a given locus (SNPs)

Available for download on Tuesday, June 25, 2024