2026 Botany Speaker Series

The CalBotSoc botany speaker series showcases and promotes the work of early career botanists, as well as other botanists doing extraordinary work. If you are an early career botanist interested in giving a talk of general interest to our members, please contact our Membership Chair. The Society also occasionally invites botanists undertaking extraordinary work in West American botany to present their current project.

Thursday, October 8, 2026 7-8pm PT

Kate Ostevik

Assistant professor, Department of Evolution, Ecology,
and Organismal Biology, University of California Riverside

Lessons from California’s Floral Diversity

California’s extraordinary floral diversity provides an opportunity to understand the processes that generate and maintain biodiversity. In the Ostevik lab, we study plant diversification through two complementary lenses: adaptation and speciation. I will highlight ongoing projects that illustrate both. First, I will discuss adaptation to drought in wild sunflower (Helianthus annuus). In a common-garden experiment, populations from more arid regions of California flower early. This is consistent with a drought-escape strategy, and this seems to have tradeoffs with drought avoidance and tolerance. A resurrection experiment comparing ancestral and contemporary populations similarly reveals a shift toward earlier flowering under increasingly dry conditions that has consequences for interactions with other species. Second, I will discuss a putative case of homoploid hybrid speciation in southern California Penstemon. Penstemon clevelandii is reproductively isolated from both parental species, P. spectabilis and P. centranthifolius. Further, although the parents are also strongly reproductively isolated, genomic evidence suggests that hybridization between them contributed to the formation of P. clevelandii. However, P. clevelandii is not a simple 50:50 mixture of the parental genomes. Instead, our results are more consistent with introgressive speciation. Determining whether this introgression directly contributed to the evolution of reproductive barriers will require further work.

Kate Ostevik is an assistant professor in the Department of Evolution, Ecology, and Organismal Biology at the University of California Riverside. She earned her Ph.D. in Botany at the University of British Columbia where she studied how adaptation to sand dunes facilitates speciation in sunflowers. As a postdoc, she moved to Duke University to study the reproductive barriers that separate species and how mating systems and hybridization can affect them. More broadly, her research centers on the fields of speciation, evolutionary ecology, and population genetics. And, she is particularly interested in how reproductive barriers, hybridization, and genome architecture influence the diversification of flowering plants.