Evolution of Novelty
Tribolium gin-traps and dual origin of insect wings
The origin of insect wings is still a highly-debated mystery in biology, despite the importance of this evolutionary innovation. There are currently two prominent, but contrasting wing origin hypotheses (the tergal origin hypothesis and the pleural origin hypothesis). Through studies in the Tribolium beetle, we have previously obtained functional evidence supporting a third hypothesis, the dual origin hypothesis. Although this hypothesis can potentially unify the two competing hypotheses, it requires further testing from various fields, including evolutionary developmental biology and paleontology. In this project I investigated the genetic regulation of the tissues serially homologous to wings in the pupal abdomen of Tribolium. I found that the formation of ectopic wings in the abdomen upon homeotic transformation relies not only on the previously identified abdominal wing serial homolog (gin-trap), but also on a secondary tissue in the pleural location. Using an enhancer trap line of nubbin (a wing lineage marker), we were able to visualize these two tissues (of tergal and pleural nature) merging to form a complete wing upon knock-down of the abdominal Hox genes. These results support the idea that the insect wing is composed of two separate lineages of tissues, and can therefore further support a dual evolutionary origin of insect wings. Our analyses also uncovered detailed Hox regulation during the development of abdominal wing serial homologs, which will be used as a foundation to elucidate the molecular mechanisms that have facilitated the evolution of bona fide insect wings, as well as the diversification of other wing serial homologs.
The dorsal head of Onthophagus beetles: an evolutionary hotspot for innovation
It is truly amazing how so few genes, developmental pathways, and morphogenetic processes suffice to generate seemingly endless shapes and forms. Accordingly, my research interests are rooted in understanding how complex novel traits may arise by deploying old genes and gene networks within new developmental and evolutionary contexts. My current work focuses on the evolutionarily dynamic dorsal head of insects, and the way in which embryonic head patterning genes are co-opted, recruited, and rewired to pattern novel, post-embryonic structures, such as the horns of Onthophagus beetles.