PS 26-74 - Examining climatic adaptation via gene flow using serpentine tolerant plants

Background/Question/Methods

Understanding how climatic changes affect plant populations is increasingly important as new climatic extremes are reached. One of the most impactful ways that climate change may affect plants is via reduced precipitation. The phenotypic effects of drought on plants can include alterations in growth pattern and rate, phenology, and rewards to pollinators, all of which can reduce plant fitness. There is evidence that climate change can also affect fitness directly by reducing pollen viability and seed set. We studied if the way that drought affects plant fitness is mediated by local adaptation to different levels of soil water availability. Serpentine soil is highly drought prone, so plants that can live both on and off serpentine are a good model system for studying effects of local adaptation on drought response. We asked if (1) drought changes growth rate, pollen viability, and seed set of the serpentine-tolerant plant Antirrhinum vexillocalyculatum, and (2) if responses to drought vary with native moisture regime and soil type. We sowed field-collected seeds from two pairs of nearby populations that differed in precipitation amount. Each pair contained one population from serpentine soil and one from non-serpentine soil.

Results/Conclusions

We found complex effects of drought on fitness and fitness-related traits, and some evidence that effects of drought on fitness are mediated by local adaptation to soil moisture. We discuss implications for plant evolution and persistence under future climate change scenarios.