Date of Award




Document Type


Degree Name

Doctor of Philosophy (PhD)


Department of Biological Sciences

Content Description

1 online resource (ii, xiii, 227 pages) : illustrations (some color)

Dissertation/Thesis Chair

Ing-Nang Wang

Committee Members

George Robinson, Wendy Turner, Dustin Brisson


Borrelia burgdorferi sensu lato, Ixodes scapularis, Lyme disease, Major ospC Groups, ospC, Ixodes, Ticks as carriers of disease, Vector-pathogen relationships

Subject Categories

Ecology and Evolutionary Biology | Evolution


The causative agents of Lyme disease, or Lyme Borreliosis, are spirochetes in the Borrelia burgdorferi sensu lato (s.l.) species complex that are transmitted by ticks in the genus Ixodes. Certain B. burgdorferi s.l. genotypes are more likely to cause invasive, disseminated infection in humans, and the gene, ospC, has been identified as a molecular marker that can be used to predict virulence. ospC is the most polymorphic locus in the B. burgdorferi s.l. genome, and different alleles have been assigned to Major ospC Groups based on sequence dissimilarity. Issues with the Major ospC Group definition and nomenclature are pervasive in the literature, and we conducted sequence comparisons of 830 B. burgdorferi s.l. sequences obtained from GenBank to resolve these issues. We defined a total of 107 Major ospC Groups from 13 B. burgdorferi s.l. species and used the geographic location of isolation for each ospC group, as well as phylogenetic reconstruction of ospC, to investigate B. burgdorferi s.l. transcontinental distribution and migration. ospC groups had recent common ancestry or had migrated between Europe and Asia, as well as Europe and North America, but not between North America and Asia, indicating there is/was a barrier to dispersal between the latter two continents. Virulent ospC groups (those that are more likely to cause invasive, disseminated Lyme disease) were more likely to have transcontinental distributions than noninvasive groups, and humans are at risk of becoming infected with these groups on all three continents.

Included in

Evolution Commons