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Local adaptation of seed and seedling traits along a natural aridity gradient may both predict and constrain adaptive responses to climate change
Author(s) -
Christie Kyle,
Pierson Natalie R.,
Lowry David B.,
Holeski Liza M.
Publication year - 2022
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/ajb2.16070
Subject(s) - biology , seedling , arid , intraspecific competition , trait , adaptation (eye) , germination , growing season , interspecific competition , genetic variation , ecology , agronomy , biochemistry , neuroscience , computer science , gene , programming language
Premise Variation in seed and seedling traits underlies how plants interact with their environment during establishment, a crucial life history stage. We quantified genetic‐based variation in seed and seedling traits in populations of the annual plant Plantago patagonica across a natural aridity gradient, leveraging natural intraspecific variation to predict how populations might evolve in response to increasing aridity associated with climate change in the Southwestern U.S. Methods We quantified seed size, seed size variation, germination timing, and specific leaf area in a greenhouse common garden, and related these traits to the climates of source populations. We then conducted a terminal drought experiment to determine which traits were most predictive of survival under early‐season drought. Results All traits showed evidence of clinal variation—seed size decreased, germination timing accelerated, and specific leaf area increased with increasing aridity. Populations with more variable historical precipitation regimes showed greater variation in seed size, suggestive of past selection shaping a diversified bet‐hedging strategy mediated by seed size. Seedling height, achieved via larger seeds or earlier germination, was a significant predictor of survival under drought. Conclusions We documented substantial interspecific trait variation as well as clinal variation in several important seed and seedling traits, yet these slopes were often opposite to predictions for how individual traits might confer drought tolerance. This work shows that plant populations may adapt to increasing aridity via correlated trait responses associated with alternative life history strategies, but that trade‐offs might constrain adaptive responses in individual traits.