New Jersey Institute of Technology Jersey City, New Jersey
Thousands of species practice social parasitism, and approximately two hundred of these are ants. One subset includes the genus Polyergus (Formicidae: Formicinae), which is made up of both specialists – parasites of a single species – and generalists – parasites of multiple species. These parasites invade the nests of their Formica (Formicidae: Formicinae) nests, stealing brood to raise as workers for the Polyergus queen. The aim of this study was to assess how parasitic specialization might influence morphological evolution across species. Are specialist parasites most similar in morphology to their hosts? Is generalist parasite morphology a mosaic of their multiple hosts? We constructed a large-scale parasite-host dataset accounting for geographical variation in which we quantified the morphology of 52 species through measurements of prepared specimens stored on the database AntWeb. Via principal component analyses of about 2,000 total measurements, we generated morphospaces that ultimately indicated that Polyergus generalists are not necessarily a morphological mosaic of the Formica they parasitize, and that specialists are not necessarily closest in morphology to their specific hosts. These results offer opportunities for expanding this study with additional analytical techniques, including future incorporation of phylogenetic relationships. Beyond ants, these results may also provide insight into parasitism and coevolution more broadly, as well trends in morphology that allow for host exploitation.
