Abstract Detail



Ecology

Love, Natalie [1], Mazer, Susan [2].

Region-specific phenological responses to climate change in Streptanthus tortuosus (Brassicaceae).

Shifts in flowering and fruiting phenology in response to directional climate change during the past century have been reported in many taxa and ecosystems, however, forecasting how species will respond to future changes in climate and predicting the ecosystem-wide consequences of these changes are still major challenges. Estimating species’ sensitivities to changes in climate (such as temperature) is a critical first step toward improving our ability to make such predictions. Many studies have focused on estimating species- and community-wide phenological sensitivities to climate, but we know little about whether sensitivities vary within species. Additionally, the potential consequences of such intraspecific variation in sensitivity to climate are not well understood. In this study, we used 743 herbarium specimens representing a 111-year collection period of the mountain jewelflower (Streptanthus tortuosus, Brassicaceae) to investigate whether individuals sampled from relatively warm regions differ in their sensitivity to climate compared to those sampled from relatively cool regions and, if so, whether this has resulted in divergent rates of phenological change over time. We evaluated the roles of two, non-mutually exclusive potential drivers of detected divergent temporal responses: (1) differences in the degree of phenological sensitivity to climate between plants sampled from warm vs. cool regions, (2) differences in the magnitude of climate change experienced by plants sampled from warm vs. cool regions, or (3) both. During the 111-year collection period, individuals sampled from warm regions show an estimated 20-day advancement in flowering date, but we found no evidence of advancement among sampled plants in cool regions. Plants sampled from warm regions exhibit higher sensitivities to temperature, the onset of the growing season, and the length of the growing season than those from cool regions. In addition, plants sampled from warm regions have experienced a greater degree of climate warming than those from cool regions. Our results suggest that the greater shift in flowering date among plants sampled from warm regions is driven both by their greater sensitivity to climate and the greater degree of climate warming experienced by these plants. Our results provide some of the first evidence that species exhibit intraspecific variation in sensitivity to climate and that it can contribute to divergent responses to climate change. Future studies attempting to use sensitivities to climate to predict shifts in phenology, whether at the level of an individual species or on a community-wide scale, should consider whether species exhibit intraspecific variation.      


1 - University of California, Santa Barbara, Ecology, Evolution, and Marine Biology, 306 Yerba Buena St., Morro Bay, CA, 93442, USA
2 - University of California, Santa Barbara, Department of Ecology, Evolution, and Marine Biology

Keywords:
phenology
herbarium specimens
climate change.

Presentation Type: Oral Paper
Number: ECO1004
Abstract ID:874
Candidate for Awards:Ecological Section Best Graduate Student Paper


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