Molecular phylogeny of Azteca ants (Hymenoptera: Formicidae) and the colonization of Cecropia trees

Despite the prominence of the Azteca-Cecropia interaction as the focus of extensive ecological investigation, a reliable phylogeny of the Azteca ants has been lacking, primarily because many of the morphological and behavioral characters are phylogenetically uninformative or conflicting. A phylogenetic analysis of a select set of Azteca ants, including six Cecropia inhabitants and two non-Cecropia inhabitants, plus an outgroup taxon, is presented on the basis of mitochondrial DNA sequences. The evolutionary relationships deduced from the molecular data are analyzed with reference to ecological and morphological studies, specifically addressing the phylogenetic relationship of structurally and behaviorally ambiguous taxa, species complex groupings, and the colonization of Cecropia trees. According to the molecular phylogeny, the Cecropia-inhabiting Azteca do not form a monophyletic clade, indicating multiple independent colonization or abandonment of Cecropia trees by the Azteca. (C) 1996 Academic Press, Inc.