The evolution of segmentation mechanisms in holometabolous insects

One of the aims of our work is to provide important insights into how developmental gene networks evolve. This can be achieved by gaining a deep understanding of the developmental genetic mechanisms operating in Tribolium, and identifying how these are similar or different to the development genetic mechanisms operating in other holometabolous insect species; e.g. the parasitic wasp Nasonia vitripennis, the honeybee Apis mellifera, the moths Bombyx mori and Manduca sexta, and the fruit fly Drosophila melanogaster (see Peel, 2008. Philos. Trans. R. Soc. Lond. B. Biol. Sci.). We are interested in using comparative developmental biology to understand how the gene networks controlling body segment formation have evolved (see Peel, Chipman & Akam, 2005. Nat. Rev. Genet.).

Ancestrally, insects developed their trunk segments sequentially, in an anterior-to-posterior progression.  This developmental trait is found in more primitive, non-holometabolous, insect species, such as grasshoppers and true bugs, as well as non-insect arthropods such as centipedes and spiders. The beetle Tribolium is an example of a holometabolous insect species that has also retained this ancestral trait during evolution.  However, many other holometaoblous insects, including Nasonia, Apis and Drosophila, have evolved a faster mode of development in which all body segments form more-or-less simultaneously.

By studying the genetic and cellular mechanisms underlying Tribolium body segment specification we can explore how this evolutionary transition from sequential to simultaneous segmentation might have occurred.