Figure 2.

Single-gene maximum-likelihood values for the number of founder lineages remaining in invasive S. invicta in the USA (a) distinguished by the class of nuclear marker. Values are derived from the coalescent simulation program CoNe by assuming 10 generations between initial colonization and sampling. Numbers at arrowheads indicate the overall maximum-likelihood values of a for each introduction scenario, with the corresponding numbers of unrelated mated founder queens shown in parentheses. Open circles, allozymes; filled circles, microsatellites; squares, sex locus.