Research in our group centers on two major themes. One theme explores compelling questions in insect macroevolution. Areas of inquiry include deciphering evolutionary patterns and processes in life cycles, host-plant relationships, complex behavior, geographic distributions, and diversity. To do this, we reconstruct phylogenies using molecular and morphological characters, then use these as a basis for inferring pattern and process. Insect groups we study currently include aphids and other Sternorrhyncha (hemipteran plant-sap feeders), Pompilidae (spider wasps), and related solitary wasps. Past studies included stratiomyid flies, dragonflies, and a guest star–Phragmatopoma marine worms(!). Our work also includes basic taxonomy, which is necessary to sort out species in understudied groups. Molecular data is instructive in this respect, particularly for morphologically challenging taxa.
Another theme concerns the evolution of bacterial endosymbiosis in sap-feeding insects. Our current focus is on Adelgidae (Sternorrhyncha: Aphidoidea) and their bacterial symbionts. We are characterizing the full (and unusual) diversity of symbionts in this group, with the aim of reconstructing patterns of symbiont gains and losses. We are sequencing the genomes of symbionts to infer the extent of their contributions to the partnership. We are further using these data to test a hypothesis regarding the pattern of symbiont acquisitions and replacements over the course of Adelgidae diversification. Ultimately, we aim to test a hypothesis explaining the unusual diversity and high turnover rate of symbionts in these insects.