Phenotypic responses of a Sierra Nevada monkeyflower to climate variation and severe drought

As climatic conditions change, species will be forced to move or adapt to avoid extinction. Exacerbated by ongoing climate change, California recently experienced an exceptional drought from 2012-2014. To investigate whether an adaptive response occurred to this event, I conducted a “resurrection” study of the cutleaf monkeyflower (Mimulus laciniatus), an annual plant, by comparing trait responses of ancestral seed collections ("pre-drought") with contemporary descendant collections ("drought"). Plants were grown under common conditions to test whether this geographically-restricted species has capacity to respond to climate stress across its species range. My research examined if traits shifted in predicted ways in response to recent, severe drought and if the responses varied by climate region. I found days to emergence (i.e. seedling emergence from soil) in the drought generation were significantly fewer as compared to the pre-drought generation. Additionally, trait variation in days to emergence was reduced in the drought generation, which may suggest that a selective event occurred. Days to first flower differed significantly by region and increased with elevation, suggesting climate adaptation across the species range. The drought generation plants were larger and had greater reproduction as compared to the pre-drought generation, which may be attributed to earlier germination of these populations in the greenhouse. My results demonstrate that rapid shifts in trait means are possible within populations, including peripheral populations of a plant species with a relatively restricted range, consistent with climate adaptation. This study highlights the need for better understanding of rapid adaptation as a means for plant communities to withstand climate change