Comparative Population Genetics of Red Imported Fire Ants (Solenopsis invicta) at the University of Central Oklahoma and Lake Arcadia, Edmond, Oklahoma

Abstract

The red imported fire ant is a well-studied pest in the southern United States, but investigations of invasions in the central region are relatively rare. We compared two central Oklahoma invasions: a newly observed urban invasion on the campus of the University of Central Oklahoma, and an established invasion around Lake Arcadia. We genotyped the General protein-9 (Gp-9) locus to determine social form and eleven microsatellites to evaluate population structure. We hypothesized that colonies were polygyne, that the repeated introductions required to reach central Oklahoma would lead to low genetic diversity, and that the two sites were independently colonized and, therefore, would be genetically isolated. As expected, the analysis of 33 sampled colonies showed that almost all were polygyne and exhibited low genetic diversity, although comparable to diversity found in previous studies. Contrary to our original hypothesis, we discovered that the two separate invasion sites of our study are not differentiated from each other. We found no evidence of distinct genetic clusters within or across sites. However, we did find evidence of two or more introductions that have become integrated. The potential for contemporary gene flow near the northern edge of the fire ant range is concerning as it allows for the maintenance of genetic variation that can lead to more effective adaptation to new environments.