Since January 2021, she lives in Saint Louis, where she is an Honorary Professor of Biology at Washington University and a Research Associate at the Missouri Botanical Garden.

[3] Renner's research interests focus on the phylogenetics, mating system evolution, and biogeography of flowering plants, in both temperate and tropical regions.

[8][9] The use of genetic tools enables Renner to track the movement of plants across ocean basins,[10][11] define the separation of land masses following the breakup of Pangaea 153 million years ago,[12][13] and define the origin of agricultural crops including cucumbers and melons[14] and gourds.

[3][17] She has tracked the relationship between Philidris nagasau ants and Squamellaria plants over the past 3 million years,[18] an interaction that is a type of farming because the ants place seeds into tree bark and then return later to eat the resulting growth.

[19] Her research followed the co-evolution between sword-billed hummingbirds and passion flowers, an interaction that has been gained and lost multiple times over the past 11 million years.