Abstract Detail

Ecophysiology

Bontrager, Megan [1], Suglia, Elena [2], Davis, John [3], Schmitt, Johanna [4], Maloof, Julin [3], Gremer, Jennifer [5].

Evolution of vernalization requirements across an elevational cline in Streptanthus tortuosus.

In mountainous regions, plants may evolve responses to seasonal cues that allow for life histories that maximize fitness in local environments. One critical life history step is the transition to flowering, which may depend upon cues such as temperature to time flowering with favorable conditions. For example, winter chilling (vernalization) may act to delay flowering until spring, particularly for higher elevation populations that experience harsh overwinter conditions. Here, we quantified vernalization requirements in Streptanthus tortuosus (Brassicaceae), a species that is widespread across the Sierra Nevada range (California, USA). S. tortuosus occupies a broad elevational range, and across this range it exhibits life histories varying from annual to short-lived perennial that are strongly linked to temperature cues. We examined the extent to which populations of S. tortuosus have differentiated in their vernalization requirements with a series of experiments that applied chilling treatments of various lengths. We included populations sourced across a 2500 m elevational range, as well as a subset of populations for which we generated family structure in order to estimate heritability of chilling requirements and their potential to evolve under changing conditions. Our results to-date generally demonstrate a cline in vernalization requirements corresponding to source elevation, with some low elevation populations flowering even in the absence of chilling, while some high elevation populations require 12 or more weeks to flower. Surprisingly, flowering responses were more varied among low elevation populations, suggesting that in some populations, flowering depends not just on environmental cues, but also perhaps on plants reaching a size threshold. Taken together with previous work demonstrating variation in germination cueing across elevations, these experiments paint a comprehensive picture of how this species has adapted to highly differentiated seasonal environments. Understanding the cueing mechanisms underlying life history variation and adaptation to local climate is key to anticipating population responses to changing climate in the intermountain west.

1 - UC Davis, Department Of Evolution And Ecology, 1 Shields Avenue, Davis, CA, 95616, United States
2 - UC Davis, Center for Population Biology, 1 Shields Avenue, Davis, CA, 95616, United States
3 - UC Davis, Department of Plant Biology, 1 Shields Avenue, Davis, CA, 95616, United States
4 - Department Of Evolution And Ecology, One Shields Avenue, Davis, CA, 95616, United States
5 - UC Davis, Department of Evolution and Ecology, 1 Shields Avenue, Davis, CA, 95616, USA

Keywords:
adaptation
life history
elevation gradients
phenology
vernalization.

Presentation Type: Oral Paper
Session: ECOPH2, Ecophysiology II
Location: /
Date: Tuesday, July 20th, 2021
Time: 12:45 PM(EDT)
Number: ECOPH2010
Abstract ID:1044
Candidate for Awards:None