Climate determines vascular traits in the ecologically diverse genus Eucalyptus

Current theory presumes that natural selection on vascular traits is controlled by a trade‐off between efficiency and safety of hydraulic architecture. Hence, traits linked to efficiency, such as vessel diameter, should show biogeographic patterns; but critical tests of these predictions are rare, l...

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Bibliographic Details
Published in:Ecology letters 2016-03, Vol.19 (3), p.240-248
Main Authors: Pfautsch, Sebastian, Harbusch, Marco, Wesolowski, Anita, Smith, Renee, Macfarlane, Craig, Tjoelker, Mark G, Reich, Peter B, Adams, Mark A, Lloret, Francisco
Format: Article
Language:English
Subjects:
Adaptation
adaptive radiation
Anatomy
angiosperm tree
aridity
Australia
biogeography
Botany
Climate
Climate change
conduit diameter
dry environmental conditions
Eucalyptus
Eucalyptus - anatomy & histology
hydraulic conductivity
natural selection
Phylogenetics
phylogeny
Plant ecology
prediction
sapwood
trees
vessel frequency distribution
water availability
wood
Wood - anatomy & histology
wood density
xylem
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Summary:Current theory presumes that natural selection on vascular traits is controlled by a trade‐off between efficiency and safety of hydraulic architecture. Hence, traits linked to efficiency, such as vessel diameter, should show biogeographic patterns; but critical tests of these predictions are rare, largely owing to confounding effects of environment, tree size and phylogeny. Using wood sampled from a phylogenetically constrained set of 28 Eucalyptus species, collected from a wide gradient of aridity across Australia, we show that hydraulic architecture reflects adaptive radiation of this genus in response to variation in climate. With increasing aridity, vessel diameters narrow, their frequency increases with a distribution that becomes gradually positively skewed and sapwood density increases while the theoretical hydraulic conductivity declines. Differences in these hydraulic traits appear largely genotypic in origin rather than environmentally plastic. Data reported here reflect long‐term adaptation of hydraulic architecture to water availability. Rapidly changing climates, on the other hand, present significant challenges to the ability of eucalypts to adapt their vasculature.
ISSN:1461-023X
1461-0248
DOI:10.1111/ele.12559