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Abstract Detail


Gamble, Devin [1], Mazer, Susan [2].

Sensitivity to climate predicts variable phenological shifts across California in a widespread native wildflower, Nemophila menziesii.

The ability of plant species to respond and adapt to changing climates is crucial in determining their fitness and, on a broader scale, their persistence. Rates of change in temperature and precipitation across the geographic range of many North American species are unlikely to be uniform, prompting the question of how responses in key traits such as phenology will vary within species. Climate-driven shifts in phenology can be adaptive when plant development tracks suitable growing conditions. Phenological sensitivity to temperature, for example, or the temporal shift in life history event per degree of change, has been positively correlated with performance. Recent studies have documented average flowering sensitivities ranging from -2.5 to -4.4 days/°C among species (i.e., plants flower 2.5-4.4 days earlier for every 1°C increase in temperature). However, there has been little research into how phenological sensitivity varies within species, which can indicate whether plants in certain parts of a species’ range are more likely than those in other parts to shift their phenology following climate change. In addition, the sensitivity of annual plants to climatic predictors other than temperature (e.g., precipitation) and to different sources of climatic variation (spatial versus interannual) remains understudied. The rich historical record of plant occurrences available from herbaria allows for thorough investigation of species’ phenological sensitivity to climate over both space and time. Using the day-of-year (DOY) of collection as a proxy for flowering date, phenology can be modeled in response to climatic and geographic predictors. Using such models, we analyzed ~1,700 specimens of a widespread California winter annual, Nemophila menziesii, collected from 1901-2019 to determine how seasonal climate conditions drive intraspecific variation in reproductive phenology. Warmer temperatures and lower rainfall predicted earlier DOYs (advancing phenology) across the range of N. menziesii. Spatial variation in both temperature and precipitation explained a higher proportion of variance in DOY, although flowering phenology was also sensitive to interannual variation in temperature (i.e., anomalies), particularly in the spring (-2.4 days/°C). Specimens collected from chronically cool locations demonstrated greater phenological sensitivity to both temperature and precipitation anomalies than those collected from warmer locations. These findings highlight the importance of studying intraspecific variation in sensitivity to climate across species’ ranges, as well as the importance of considering spatial and temporal scales of climatic variation in phenological research, which can lead to improved predictions for how populations will adjust their development in response to changing environmental conditions.

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1 - University of California, Santa Barbara, Ecology, Evolution, and Marine Biology, 4213 Life Sciences Building, Santa Barbara, CA, 93106, USA
2 - University Of California, Santa Barbara, Department Of Ecology & Marine Biology, 4119 Life Sciences Building, Santa Barbara, CA, 93106, United States

herbarium specimens
phenological sensitivity
climate change
flowering time.

Presentation Type: Poster
Session: P1, Ecology Posters
Location: Virtual/Virtual
Date: Monday, July 19th, 2021
Time: 5:00 PM(EDT)
Number: P1EC005
Abstract ID:485
Candidate for Awards:None

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