Associate Professor University of California Merced, California
Many insects depend on bacterial symbionts for essential nutrition. However, bacteria pose challenges for their hosts as they lose genes involved in most essential cellular functions. The evolutionary strategies hosts use to maintain these symbionts, and then replace them when benefits end, remains poorly understood. Leafhopper insects offer a key model to address these questions. They generally rely on two intracellular symbionts for complete nutrition. These symbionts are among the most ancient and genomically degraded known, leading to their occasional replacements. To sustain and support symbionts, leafhopper hosts evolve novel organs and functional traits that involve thousands of genes. These genes are derived from horizontal gene transfers to the host genome, reassignment of mitochondrial support genes, and gene-family duplications. Some of these host-encoded genes enter the bacterial cell matrix to support fundamental cellular processes. When younger symbionts replace older less efficient ones, hosts again evolve novel organs and support systems.
