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Title: POPULATION GENETICS OF THE INVASIVE FIRE ANT SOLENOPSIS INVICTA IN THE U.S.A.

Author
item Shoemaker, David

Submitted to: International Union for the Study of Social Insects Congress
Publication Type: Proceedings
Publication Acceptance Date: 6/13/2006
Publication Date: 8/30/2006
Citation: Shoemaker, D.D. 2006. Population Genetics of the Invasive Fire Ant Solenopsis invicta in the U.S.A.. XV Congress IUSSI Proceedings. 115-116. Washington, D.C. July 30-August 4, 2006.

Interpretive Summary:

Technical Abstract: Analyses of population genetic variation in invasive species can provide information on the history of the invasions, breeding systems, and gene flow patterns. We surveyed genetic variation in both social forms of the red imported fire ant, Solenopsis invicta, throughout the species’ introduced range in the U.S.A. to learn how the unique breeding biology of each form shapes genetic structure at various scales, to discern genetic footprints of the invasion process, and to reconstruct the origin and spread of each form. Our analyses revealed significant local mtDNA differentiation in the polygyne (multiple colony queens) but not the monogyne (single colony queen) social form, as well as pronounced mtDNA differentiation coupled with weaker nuclear differentiation between sympatric populations of the two forms. At a larger scale, we found no mtDNA but significant nuclear regional differentiation. In general, populations were most similar to other populations of the same social form at their mtDNA genomes. These higher-level patterns of structure are consistent with the spread of the ant by long-distance, human-mediated dispersal, with sub-founder populations of each form typically established by queens of the same form. Bayesian analyses showed that study populations most distant from the claimed site of entry, Mobile, Alabama, have diverged most from the hypothetical founder population, consistent with an invasion scenario in which the ants spread outward from Mobile through repeated sub-founder events. Several lines of evidence raise the possibility of secondary introductions of S. invicta into the U.S.A.