The insect visual system as a model for neural development and evolution
Animal genomes provide instructions for producing an amazing diversity of cell types during development, perhaps especially in the brain. One of the most surprising findings in the genome-sequencing era has been how few genes there are – only about 25,000 in most animal genomes regardless of their size or complexity. How do these genes interact during development to produce the incredible diversity of cell types? What kinds of genetic changes have allowed neural cell types to be modified or to increase in number across species over evolutionary time? In order to address such questions, my lab uses the insect retina as a model to understand the genetic basis of neural cell type evolution. Insect eyes can be incredibly diverse in some ways and yet rigidly conserved in others. Compound eyes are highly recognizable given their characteristic structure. Yet these structures can vary in morphology and underlying organization in sometimes dramatic ways to help adapt insects to thrive in diverse environments around the world. For example, butterflies have expanded color vision using a more complex retinal mosaic, while house flies have a novel neural type that improves target detection and tracking. Hidden underneath the surface, mosquito eyes have dramatically rearranged and highly regionalized retinas, potentially for host and water detection. In this talk, I will present data which suggests that, overall, insect eye patterning is incredibly highly conserved and uses the same transcription factors and signaling pathways to define core cell types across species. This begs the question: What kinds of genetic changes underlie the dramatic differences found in some groups? How does this deeply conserved, highly organized feature evolve modified or novel functions? My lab is using a combination of new genomic and genetic tools such as single cell sequencing and CRIPSR/Cas9 genome editing to characterize differences across species, test the function of candidate genes directly in species of interest, and to identify and test gene regulatory regions responsible for neural cell type evolution. We aim to uncover how gene regulatory networks can be modified to reorganize tissues and to produce novel types of cells.