Movie above: the beginning of embryogenesis in the cricket Gryllus bimaculatus. Movie by Seth Donoughe from his paper on cricket embryonic development.
Although the insect body plan is well conserved, the developmental mechanisms of body patterning are surprisingly varied. The fruit fly Drosophila melanogaster has long served as a model organism to investigate the molecular mechanisms regulating embryonic axial patterning, long germ segmentation (in which all body segments are established near-simultaneously), and acquisition of specific body region and segment identities. However, basally branching insects and other arthropods develop their segments in a sequential fashion, similar to non-insect arthropods and to vertebrates. The arthropod body plan, including appendage development, has also undergone extensive evolutionary modifications in different clades.
Movie above: the middle stages of embryogenesis in the cricket Gryllus bimaculatus. Movie by Seth Donoughe from his paper on cricket embryonic development.
We have studied the evolution of the underlying genetic mechanisms that result in the differences in arthropod body patterning using a number of model organisms and developmental processes. These include segmentation in the cricket Gryllus, appendage development in daddy longlegs, and Hox genes in scorpions. In the process, we have helped collaborator Prashant Sharma (American Museum of Natural History) develop the harvestman Phalangium opilio into the first daddy longlegs model laboratory system suitable for functional genetic analysis.
The outcome of the developmental processes shown in the movies above is the body plan of the cricket Gryllus bimaculatus. Shown here is a sexually mature adult female.