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Elevated CO 2 boosts reproduction and alters selection in northern but not southern ecotypes of allergenic ragweed
Author(s) -
Stinson Kristina A.,
Albertine Jennifer M.,
Seidler Tristram G.,
Rogers Christine A.
Publication year - 2017
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 - 10.3732/ajb.1700222
Subject(s) - ecotype , biology , ambrosia artemisiifolia , phenology , pollen , intraspecific competition , local adaptation , biomass (ecology) , adaptation (eye) , natural selection , botany , selection (genetic algorithm) , reproduction , ecology , agronomy , ragweed , population , allergy , demography , neuroscience , artificial intelligence , sociology , computer science , immunology
PREMISE OF THE STUDY: Many plants increase reproduction in response to rising levels of atmospheric CO 2 . However, environmental and genetic variation across heterogeneous landscapes can lead to intraspecific differences in the partitioning of CO 2 ‐induced carbon gains to reproductive tissue relative to growth. METHODS: We measured the effects of rising atmospheric CO 2 on biomass allocation in the allergenic plant Ambrosia artemisiifolia (common ragweed) across a geographic climate gradient. We grew plants from three latitudes at 400, 600, and 800 µL·L −1 CO 2 and analyzed biomass allocation and natural selection on flowering phenology and growth. KEY RESULTS: Both the latitude of origin and CO 2 treatment had significant effects on allocation and on estimates of selection. Northern plants were under stronger selection than southern plants to flower quickly, and they produced larger seeds and more reproductive mass per unit of growth. Northern plants were under stronger selection than southern plants to flower quickly, and they produced larger seeds and more reproductive mass per unit of growth. While all plants grew larger and produced heavier seeds at higher CO 2 , only northern plants increased male flower production. Both size and time to flowering were under selection, with a relaxation of the size–fitness function in northern ecotypes at high CO 2 . CONCLUSIONS: Northern ecotypes allocate more CO 2 ‐induced carbon gains to reproduction than do southern plants, pointing to a geographic gradient in future pollen and seed production by this species arising from local adaptation. Relaxed selection on size at elevated CO 2 could amplify reproductive enhancements to northern ecotypes, although more growth and seed provisioning can be expected overall. Our results demonstrate potential for ecotypic divergence in ragweed responses to climate change.