Abstract Detail



Physiology & Ecophysiology

Faulkner, Alexai [1].

Adaptive evolution of Clarkia xantiana ssp. xantiana in response to the recent California drought.

Climates are changing worldwide, but we have a very limited understanding of how native plant populations will respond to these changes. In order to survive, populations must either track climatic changes through dispersal or adapt to novel climatic conditions via evolution of ecologically important traits. Accumulating evidence indicates that adaptation can occur over fairly short timescales, and an effective method of observing this rapid adaptive evolution in natural flora is through “resurrection studies.” In these studies, cohorts of plants from before and after some selective event (fragmentation, warming, drought, etc.) are reared in a common environment and compared for some set of traits. Contemporary environmental anomalies provide us with a natural selection experiment which, when exploited for a resurrection study, helps aid us in predicting general responses to increased frequency of certain climatic anomalies. We utilized seed collected from three populations of a California endemic annual (Clarkia xantiana ssp. xantiana (Onagraceae)) before and after the recent record-breaking California drought to explore whether these populations showed evidence of rapid evolution in response to drought. We grew plants from seed collected just before the drought began (2011), during the last year of the drought (2015), and after a recent high precipitation year (2017). The greenhouse experiment included 20 maternal families, each with two replicates, for each population X year combination (N = 360 plants). We hypothesized that the drought had resulted in selection on a suite of traits potentially important for adaptation to increased drought conditions: relative growth rate, specific leaf area (SLA), and phenology. All data have been collected and are currently being analyzed. We predict that post-drought populations will have accelerated flowering times compared to pre-drought populations due to the fitness advantage earlier flowering times give in drought conditions. We also expect to see a decrease in Specific Leaf Area (SLA) in post-drought populations as a decrease in SLA should cause greater drought tolerance. Additionally, growth rates of post-drought populations are predicted to decrease, as evidence from a sister subspecies (C. x. parviflora) shows that conservative growth is favored in more arid conditions.


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Keywords:
adaptive evolution
stress adaptation
Climate change
relative growth rate
phenology
drought tolerance
Resurrection approach.

Presentation Type: Poster
Number: PPE014
Abstract ID:927
Candidate for Awards:Physiological Section Best poster presentation,Physiological Section Physiological Section Li-COR Prize


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