Host genetic variation & the microbiome

Aphids harbor a simple community of bacteria that are transmitted from mothers to offspring. The patterns of symbiont infection within and among aphid species are non-random, and we’ve found that some of this variation can be explained by genetic differences among hosts. We are harnessing this natural host genetic variation to understand:

• The effect of host mechanisms on symbiont community structure and function and how these mechanisms are evolving

• How host immune systems manage their dual role of combatting harmful infections while fostering beneficial microbes

• How host genetic variation shapes symbiont genome evolution

Protective symbionts & host-pathogen coevolution:

Animal-associated microbes often have specific phenotypic effects on their hosts—for example Regiella insecticola makes aphids resistant against an important natural enemy, the fungal pathogen Pandora neoaphidis. We are studying this three-way coevolutionary interaction to learn:

• Why and how microbes protect their hosts from pathogens and what keeps ‘beneficial’ microbes from cheating

• How symbiotic partners achieve specificity within and among species and what these patterns teach us about host-microbe coevolution

Heritable viruses & lateral gene transfer:

Vertically-transmitted viruses are often hidden players affecting host phenotypes. There are a number of vertically transmitted viruses found across aphid species, especially in the subfamily Densovirinae, and viral genes have been frequently incorporated into aphid genomes. We’re using this system to study:

• What function conserved endogenous viral elements serve in aphid genomes

• How heritable viruses act as hidden drivers of insect evolution