Rapid Evolutionary Responses to Global Change  

Dr. Carol Eunmi LEE
Department of Integrative Biology  

University of Wisconsin, Madison

430 Lincoln Drive, Birge Hall
University of Wisconsin
Madison, WI 53706

Office:  (608) 262-2675
Lab:  (608) 262-9225


     Host-Microbial interactions during Habitat Invasions

Copepods likely form the largest biomass of metazoans on the planet, yet their microbiota have been largely unexplored. The microbial community associated with copepods might perform key metabolic processes that affect host fitness and ecosystem functioning. In addition, copepods have been hypothesized to serve as major carriers and reservoirs for many waterborne pathogens. Our metagenomic sequencing of the microbiome associated with populations of the copepod Eurytemora affinis  complex uncovered a wide variety of potentially pathogenic taxa, including Salmonella, Shigella, Campylobacter, Corynebacterium diphtheriae, Yersinia, Aeromonas hydrophila, and Acinetobacter haemolyticus, as well as Vibrio cholerae. Thus, invasions by populations of the copepod E. affinis complex could potentially have serious implications for disease transmission (Gelembiuk et al. In Prep.).

Our high-throughput sequencing efforts have revealed a high diversity of microbial taxa associated with the E. affinis complex, including many undescribed genera and families (Gelembiuk et al. In Prep.; Bontrager et al. In Prep.). The microbial assemblage within the copepod differs sharply from that of the surrounding water. We also observed parallel shifts in microbial composition during independent invasions from saline to freshwater habitats. Interestingly, a core set of microbial taxa remained present in all copepod populations across all locations. This constancy suggests that populations of the E. affinis complex might be transporting certain microbial constituents as it invades.

We are currently exploring the interactions between the copepod host and its core microbiome and whether the interactions evolve during invasions. We have found microbial constituents that might serve critical functions in global biogeochemical cycles (e.g. N-fixation, denitrification), as well as those that might have important functions for host fitness during invasions (e.g. by producing antibiotics or nutrition) (Gelembiuk et al. In Prep.). Core members of the copepod microbiome include taxa that are known to produce antibiotics (e.g. Streptomyces, Pseudonocardia). The same genera have been found to protect insect hosts from bacterial infection (Kaltenpoth et al. 2006; Sen et al. 2009; Kroiss et al. 2010; Poulsen and Currie 2010). Such microbes might aid in resistance to novel pathogens during invasions into the novel range. Another core member of the E. affinis  complex microbiome, Klebsiella sp., has been found to provide insect hosts with a nitrogen source through nitrogen-fixation (Behar et al. 2008). Species of Vibrio that are common inhabitants of the  E. affinis  complex have been found to play a role in algal digestion in invertebrates (Sawabe et al. 1995; Islam et al. 2002). We are currently culturing a few of the common bacterial constituents residing in the copepod and are in the process of conducting some functional analyses.