COS 249-5 - Effects of varying simulated herbivory and drought on life history and fitness in a native California plant

Thursday, August 18, 2022

2:30 PM – 2:45 PM EDT

Location: 513E

Presenting Author(s)

ES

Elena R. Suglia

PhD Candidate
University of California, Davis
West Sacramento, California, United States

Slides (PDF)

Coauthor(s)

DD

Danielle De La Pascua

University of California, Davis
Davis, CA, United States
MG

Melody Griffith

University of California, Davis, United States
DP

Dinh Hieu Pham

University of California, Davis, United States
YW

Yasmin Wadhwani

University of California, Davis, United States
SS

Sharon Y. Strauss

Professor
University of California, Davis, United States
JG

Jennifer R. Gremer

Associate Professor
University of California, Davis
Davis, CA, United States

Background/Question/Methods

Anthropogenic climate change is rapidly altering natural systems and exposing organisms to novel combinations of abiotic and biotic conditions. Changes in precipitation regimes, plant phenology, and plant-herbivore interactions have already been observed due to climate change, with the potential to impact individual fitness, life history trade offs, and population dynamics. Understanding how abiotic and biotic factors interact to affect life history expression, fitness, and population persistence is essential for accurately predicting the potential for adaptation to future climate-induced environmental change.

Here, we examine how variation in herbivory extent and timing, as well as water availability affects intraspecific life history responses. We conducted two common garden experiments using the native California wildflower Streptanthus tortuosus, which experiences variation in water availability and herbivory and displays variable life history strategies across its range. In the first experiment, we exposed four high elevation populations to clipping treatments simulating varying frequency and intensity of mammalian herbivory at different phenophases. In the second, we exposed eight populations to factorial combinations of clipping timing and watering treatments representing range-wide field conditions. Together, the experiments simulated different combinations of herbivory frequency, timing, and drought levels across populations of S. tortuosus to determine their effects on phenology and fitness.

Results/Conclusions

Preliminary results suggest that drought, and herbivory extent and timing all affect flowering phenology and fitness. In the first experiment, plants were more likely to survive for longer periods of time in response to increasing herbivory (significantly so if herbivorized more than once), potentially leading to increased facultative perenniality and iteroparity. Later herbivory overall delayed peak flowering and later herbivory also reduced fecundity across both experiments. Additionally, drought accelerated peak flowering and decreased flowering duration. At the end of the growing season when watering was cut off to simulate Mediterranean summer drought, individuals died later if they had been exposed to higher drought levels throughout the experiment, suggesting individuals responded plastically to experimental drought conditions by increasing resilience to low water availability. Taken together, results show that herbivory and drought regimes impact population-level variation in phenology, fitness, and life history. Understanding how abiotic and biotic factors impact life history expression, fitness, and population dynamics is essential for accurately predicting the potential for adaptation to future climate-induced environmental change.