Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

Cahan, Sara


The ant genus Lasius (Formicinae) arose during the early Tertiary approximately 65 million years ago. Lasius is one of the most abundant and widely distributed ant genera in the Holarctic region, with 95 described species placed in six subgenera: Acanthomyops, Austrolasius, Cautolasius, Chthonolasius, Dendrolasius and Lasius. Many species of Lasius have been central to numerous species-level studies and the focus of many ecological, agricultural, and behavioral investigations. The focus of this study was to use molecular phylogenetic analysis of 781 base pairs of the mitochondrial gene cytochrome oxidase I (COI) and 251 base pairs of an anonymous nuclear gene (ANG) to address questions about the evolutionary relationships of North American Lasius species and subgenera. These relationships were used to better understand the biological and evolutionary complexities associated with these species given their North American distributions. The resulting hypotheses generated in this study from the analyses of these genes produced unexpected patterns of phylogenetic placement of Lasius species and subgenera. A number of biological processes alone or together could explain these patterns, including interspecific hybridization and gene introgression, incomplete lineage sorting, and the presence of multiple cryptic species.