Honors College Theses

Publication Date



Biology (B.S.B.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. John Scott Harrison


Widow spiders (genus Latrodectus) possess neurotoxic venom that varies in potency among species. α-latrotoxin is the main protein in widow venom that affects vertebrates, including humans. The European black widow, Latrodectus tredecimguttatus, is currently the only species in this genus where the gene for α-latrotoxin has been characterized. The study presented here characterizes the genetic composition of α-latrotoxin from two additional species, the brown widow (L. geometricus) and the southern black widow (L. mactans). Genetic differences among the three species were quantified for α-latrotoxin. Between species genetic divergence in α-latrotoxin was also compared to that of a second gene, cytochrome oxidase I (COI), which is not associated with Latrodectus venom. Functional genetic differences among species were high with amino acid differences ranging from 14% - 58%. Amino acid divergence was approximately 3.7 times greater between species in α-latrotoxin than in COI.