Speaker: Mr. Dustin Dial, Graduate Research Assistant, University of Georgia, USA [website]

Title: Endosymbiont genome evolution and the dynamics of host-symbiont interplay across changing diets in the sap-feeding Adelgidae

Abstract: 

Sap-feeding insects often harbor one or more intracellular symbionts that cooperate to produce essential nutrients lacking in their diet. Adelgids are unusual in that their dual-obligate symbionts have been repeatedly replaced over their relatively short evolutionary history. By sequencing 48 adelgid symbiont genomes, we show that these bacteria are diverse nutritional partners with genome contents that reflect a wide range of ages. Previously, we hypothesized that the high rate of symbiont turnover in adelgids has been driven by fluctuating selection for symbiont nutritional functions, linked to the complex life cycle of the host and its varying nutrient levels. We quantify symbiont titer and density, the number of symbiotic host cells, and differential gene expression of both host and symbionts on high- and low-nutrient diets in the species Adelges cooleyi. Our findings suggest that both the host and symbionts respond to changing dietary inputs, which may represent an adaptive strategy to maximize the reproductive success of the consortium.