Term of Award

Spring 2009

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

Laura B. Regassa

Committee Member 1

Lorenza Beati

Committee Member 2

Oscar J. Pung


Spiroplasmas are among the smallest self replicating organisms known. They are helical, motile descendents of Gram-positive bacteria that have evolved to occupy broad host ranges including plants, insects and crustaceans. Spiroplasmas are the causative agent of several economically important agricultural diseases, but most host-microbe interactions appear to be commensal. Given the ubiquitous nature of these microbes, a methodical approach that focused on serologically distinct isolates from a single host family was used as an initial step in understanding spiroplasma diversity and distribution. Tabanid-associated spiroplasmas represent the most thoroughly studied group to date, so this project examined a spiroplasma field isolate collection (>200 isolates) that was obtained from tabanid flies in Costa Rica, Ecuador, Australia, and the United States. The 16S rRNA, 23S rRNA, and rpoB genes and the 16S-23S rRNA spacer region were successfully used to establish evolutionary relationships of the closely related spiroplasma isolates. Phylogenetic analyses and non-genetic character mapping indicated that all study isolates belonged to the Apis clade; arginine hydrolysis was a strong indicator of evolutionary relatedness; surface serology and phylogenetic placement were congruent; and neither host specificity nor geographical ranges were strict.

Research Data and Supplementary Material