Rachel Vannette

“I am interested in understanding and predicting how microbial communities influence interactions between plants and insects,” she said. “In the Vannette lab (in Briggs Hall), we use tools and concepts from microbial ecology, chemical ecology, and community ecology to better understand the ecology and evolution of interactions among plants, microbes and insects."

A native of Hudsonville, Mich., Vannette received her bachelor of science degree in biology with honors at Calvin College, Grand Rapids, Mich., and her doctorate in ecology and evolutionary biology from the University of Michigan, in 2011. Her dissertation was entitled “Whose Phenotype Is It Anyway? The Complex Role of Species Interactions and Resource Availability in Determining the Expression of Plant Defense Phenotype and Community Consequences.”

In her PhD research, she examined how variation in nutrient availability and plant associations with mycorrhizal fungi belowground influenced defense chemistry in milkweed plants and the performance of a specialist herbivore (Danaus plexippus). She found that resource-based tradeoffs can in part explain plant allocation to antiherbivore defense and mycorrhizal fungi. This work also describes that plant genotypes vary in their investment in defense and associations with belowground fungi.

As a Stanford University postdoctoral fellow, funded by a life sciences research fellowship, Vannette examined the community ecology of plant-associated microorganisms. Using diverse systems, she studied the assembly of microbial communities, microbial response to anthropogenic changes like habitat fragmentation, and microbial effects on plant-pollinator interactions.

• Community ecology of plant-associated microbial communities. She explored what mechanisms shape the structure and function of microbial communities associated with plants, and how to assemble mechanisms to better understand functions, including the effects on insect herbivores and pollinators. She also researched how ants influence microbial community structure and nectar characteristics in coffee agroecosystems.
• Nectar ecology. Knowing that yeasts and bacteria are common inhabitants of flowers, and attain high densities in floral nectar, she researched how these microbes influence plants and pollinators, the mechanisms involved, and evolutionary ecology of these interactions. She also studied how nectar constituents influence pollinator foraging and health.
• Influence of anthropogenic changes on plant-microbe (insect) interactions. She researched how fragmentation affects fungal community composition in the rhizosphere of  Meterosideros polymorpha, a species of flowering evergreen tree in the myrtle family. She also studied elevated carbon dioxide changes plant-microbe-insect interactions, and researched the effects of mycorrhizal fungi on plant defense and plant-herbivore interactions.

The National Wildlife Research Foundation featured Vannette's research on monarchs and milkweed in its March 11, 2013 piece on “Catering to Butterfly Royalty." The article, by author Doreen Cubie, focused on Vannette's research as a graduate student at the University of Michigan. Vannette and advisor Mark Hunter studied five common species of milkweeds, the host plant for monarchs. They found that climate change may disrupt the chemistry of milkweeds, and encouraged gardeners to help the monarchs by planting more of these critical host plants.

Vannette and Hunter grew the plants in open-air chambers, “exposing them to elevated amounts of carbon dioxide designed to mimic Earth's atmosphere in the future,” wrote Cubie. “Although most of the plants grew slightly larger, the composition of plant leaves changed dramatically. Most of the milkweed families decreased their production of toxins, some by as much as 50 percent. The extra carbon dioxide exposure toughened the leaves, a problem for the caterpillars.

Last March Vannette was an invited speaker on the ecology and evolution of the microbiome at the University of Michigan Early Career Scientists' symposium in Ann Arbor, Mich.

Among her recent publications:

• Co-author of “Plant-Derived Variation in the Composition of Aphid Honeydew and its Effects on Colonies of Aphid-Tending Ants,” published in November 2014 in the journal Ecology and Evolution.
• Lead author of “Genetic Variation in Plant Below-Ground Response to Elevated CO₂ and Two Herbivore Species,” published in July 2014 in Plant Soil.
• Co-author of “Honey Bees Avoid Nectar Colonized by Three Bacterial Species, but not by a Yeast Species, Isolated from the Bee Gut,” published in a January 2014 edition of PLOS ONE.
• Lead author of “Historical Contingency in Species Interactions: Towards Niche-Based Predictions,” published November 2013 in Ecology Letters. (Recommended by the Faculty of 1000)