How did complete metamorphosis of “higher” insects, such as flies and moths, arise from direct developing ancestors? We are using the milkweed bug, Oncopeltus fasciatus to address the roles of genes that regulate metamorphosis in a direct developer. Our goal is to identify the key genetic and endocrine changes that have led to the emergence of complete metamorphosis. We are using the hemimetabolous milkweed bug to investigate the role of genes that have been shown to regulate metamorphosis in flies and moths. Our investigations with the broad gene in particular have suggested that a shift in the timing of expression of this key regulator has allowed the emergence of metamorphic life history in insects.  Our future work will seek to identify the endocrine and genetic factors that differentially regulate broad expression in the two types of life history. 

In a related project, we are interested in learning if changes in broad complex regulation underlie other life history polymorphisms. In a recent collaboration with Alex Hayward and Jeya Kathirithamby, we were able to show that shifts in broad expression correlate with neotenic development in insects that undergo ‘hypermetamorphosis’. Future studies will address whether such shifts underlie the developmental basis for environmentally-induced polyphenisms, such as those found in aphids, or caste determination of ants and termites. 

 © Deniz Erezyilmaz 2015