Projects
Expression QTL (eQTL) mapping of social life histories: As the honey bee genome was sequenced, the lab of Dr. Robert Page and our group landed three pollen hoarding QTL, pln-1, pln-2, pln-3 and an associated QTL pln4, on the assembled scaffolds. These regions likely contain regulators of central aspects of honey bee social life history, as exemplified by the high and low pollen-hoarding strains. There are approximately 140 candidate genes in the QTLs overall, including central components of the IIS and TOR signaling cascades (links to PDF). We now work through each of these genes to establish their expression in the high and low pollen-hoarding strains. Thereafter, we will construct crosses for eQTL mapping to aid identification of the genes responsible for the social life history syndromes of the honey bee.
Functional genomics of social organization: The RNAi tool (links to PDF) has greatly improved our ability to investigate regulation of honey bee social behavior. We study the effects of gene activity on complex phenotypic traits involved in division of labor and foraging preference. Much of our published work has focused on the vitellogenin gene, which encodes a yolk precursor protein (links to PDF). This product appears to act as an endocrine factor in honey bees, and we have established pleiotropic effects on juvenile hormone levels, foraging onset, foraging preference and longevity. With this work, our group was the first to use RNAi to understand social organization in an invertebrate (links to PDF).
Comparative proteomics of social organization: Proteomics describes the study of the complement of proteins and their modifications. The approach provides insight into whole-body- as well as tissue-specific differences in protein levels, and in combination with genetic and functional genomic methods it can greatly deepen the understanding of honey bee development and life history regulation. One of the most widely used techniques in this expanding field is mass spectrometry. We employ a combination of liquid chromatography and mass spectrometry to reveal general differences between samples on the protein level. Moreover, a major theme in most – if not all – signaling pathways is reversible protein phosphorylation. Hence, we also strive for identification and quantification of protein phosphorylation events on the major target proteins of honey bee IIS.
MicroRNA (miRNA) and social life history regulation: miRNAs are short (20-25bp) non-coding RNAs that regulate gene expression through post-transcriptional suppression of mRNA. Abundance and conservation of miRNA between species and their altered expression during development and differentiation indicates they play fundamental regulatory roles. Some of these miRNAs show differential expression patterns during development and/or at the caste level of honey bees, suggesting critical functions in social regulation of gene expression. Our work focuses on deciphering the functions of miRNAs in honey bee IIS, with emphasis on caste differentiation and worker life history regulation.
Heuristic value of the Reproductive Ground Plan Hypothesis: Our hypothesis explains how the building blocks of hymenopteran sociality were co-opted from the reproductive regulatory systems of their solitary ancestors (links to PDF). While our research on honey bees has shown strong evidence for this framework, little has been done to explore the commonality of this principle across taxa. To this end, ants (Formicidae) are particularly useful, as they represent an independent social lineage. We study the reproductive and hormonal physiology of California harvester ants (Pogonomyrmex californicus) to understand both the proximate causes of behavioral changes in social hymenoptera and the evolutionary dynamics behind them.
