Trade‐offs among carbon sinks constrain how trees physiologically, ecologically, and evolutionarily respond to their environments. These trade‐offs typically fall along a productive growth to conservative, bet‐hedging continuum. How nonstructural carbohydrates (NSCs) stored in living tree cells (known as carbon stores) fit in this trade‐off framework is not well understood. We examined relationships between growth and storage using both within species genetic variation from a common garden, and across species phenotypic variation from a global database. We demonstrate that storage is actively accumulated, as part of a conservative, bet‐hedging life history strategy. Storage accumulates at the expense of growth both within and across species. Within the species Our findings impact our understanding of basic plant biology, fit storage into a widely used growth‐survival trade‐off spectrum describing life history strategy, and challenges the assumptions of passive storage made in ecosystem models today.
Non‐structural carbohydrate (NSC) storage may be under strong selection in woody plant species that occur across broad environmental gradients. We therefore investigated carbon (C) allocation strategies in a widespread non‐native woody plant, We established an experimental common garden using genotypes of Autumn NSC concentrations were 50% higher in genotypes from sites with episodic spring freeze events compared to genotypes from warmer sites. These cold‐adapted genotypes also had a 2.3‐fold higher starch to soluble sugar ratio than warm‐adapted genotypes. Across all genotypes and seasons, NSC storage was inversely correlated with growth and reproduction. Results suggest that
A free
- NSF-PAR ID:
- 10450143
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Functional Ecology
- Volume:
- 35
- Issue:
- 8
- ISSN:
- 0269-8463
- Page Range / eLocation ID:
- p. 1640-1654
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary Populus trichocarpa , genetic trade‐offs show that for each additional unit of wood area growth (in cm2 yr−1) that genotypes invest in, they lose 1.2 to 1.7 units (mg g−1NSC) of storage. Across species, for each additional unit of area growth (in cm2 yr−1), trees, on average, reduce their storage by 9.5% in stems and 10.4% in roots. -
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Abstract Rapid adaptation can aid invasive populations in their competitive success. Resource allocation trade‐off hypotheses predict higher resource availability or the lack of natural enemies in introduced ranges allow for increased growth and reproduction, thus contributing to invasive success. Evidence for such hypotheses is however equivocal and tests among multiple ranges over productivity gradients are required to provide a better understanding of the general applicability of these theories.
Using common gardens, we investigated the adaptive divergence of various constitutive and inducible defence‐related traits between the native North American and introduced European and Australian ranges, while controlling for divergence due to latitudinal trait clines, individual resource budgets, and population differentiation, using >11,000 SNPs.
Rapid, repeated clinal adaptation in defence‐related traits was apparent despite distinct demographic histories. We also identified divergence among ranges in some defence‐related traits, although differences in energy budgets among ranges may explain some, but not all, defence‐related trait divergence. We do not identify a general reduction in defence in concert with an increase in growth among the multiple introduced ranges as predicted trade‐off hypotheses.
Synthesis : The rapid spread of invasive species is affected by a multitude of factors, likely including adaptation to climate and escape from natural enemies. Unravelling the mechanisms underlying invasives' success enhances understanding of eco‐evolutionary theory and is essential to inform management strategies in the face of ongoing climate change.OPEN RESEARCH BADGES This article has been awarded Open Materials, Open Data, Preregistered Research Designs Badges. All materials and data are publicly accessible via the Open Science Framework at
https://doi.org/10.6084/m9.figshare.8028875.v1 ,https://github.com/lotteanna/defence_adaptation ,https://doi.org/10.1101/435271 . -
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Abstract Under climate change, ectotherms will likely face pressure to adapt to novel thermal environments by increasing their upper thermal tolerance and its plasticity, a measure of thermal acclimation. Ectotherm populations with high thermal tolerance are often less thermally plastic, a trade‐off hypothesized to result from (i) a phenotypic limit on thermal tolerance above which plasticity cannot further increase the trait, (ii) negative genetic correlation or (iii) fitness trade‐offs between the two traits. Whether each hypothesis causes negative associations between thermal tolerance and plasticity has implications for the evolution of each trait.
We empirically tested the limit and trade‐off hypotheses by leveraging the experimental tractability and thermal biology of the intertidal copepod
Tigriopus californicus . Using populations from four latitudinally distributed sites in coastal California, six lines per population were reared under a laboratory common garden for two generations. Ninety‐six full sibling replicates (n = 4–5 per line) from a third generation were developmentally conditioned to 21.5 and 16.5°C until adulthood. We then measured the upper thermal tolerance and fecundity of sibships at each temperature.We detected a significant trade‐off in fecundity, a fitness corollary, between baseline thermal tolerance and its plasticity.
Tigriopus californicus populations and genotypes with higher thermal tolerance were less thermally plastic. We detected negative directional selection on thermal plasticity under ambient temperature evidenced by reduced fecundity. These fitness costs of plasticity were significantly higher among thermally tolerant genotypes, consistent with the trade‐off hypothesis. This trade‐off was evident under ambient conditions, but not high temperature.Observed thermal plasticity and fecundity were best explained by a model incorporating both the limit and trade‐off hypotheses rather than models with parameters associated with one hypothesis. Effects of population and family on tolerance and plasticity negatively covaried, suggesting that a negative genetic correlation could not be ruled as contributing to negative associations between the traits. Our study provides a novel empirical test of the fitness trade‐off hypothesis that leverages a strong inference approach. We discuss our results' insights into how thermal adaptation may be constrained by physiological limits, genetic correlations, and fitness trade‐offs between thermal tolerance and its plasticity.
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Abstract Intraspecific diversity of dominant species in native plant communities can modulate ecosystem function under both optimal and stressful conditions. Yet, few genotype by environment interaction studies quantify differences in the shape of plasticity functions or phenotypic breakpoints across genotypes in natural populations.
Using three genotypes with a history of drought selection, we performed a greenhouse study on the dominant tallgrass prairie species
Andropogon gerardii . We investigated phenotypic plasticity and recovery differences among genotypes across a water availability gradient, measuring growth‐related, instantaneous and cumulative phenotypes. To further understand genotype by environment effects, we quantified plasticity functions and breakpoints among genotypes.Like other studies, we found strong evidence for phenotypic and plasticity differences among genotypes. However, we also found nonlinear plasticity functions and breakpoints were common across phenotypes, especially relative growth rates, biomass allocation and root architecture. Drought selected genotypes were also more likely to flower during recovery, but all genotypes were resilient to drought across treatments.
We demonstrate that plasticity functions may help explain intraspecific diversity, patterns of selection and nonlinear community responses to more variable rainfall within an experimental population. In particular, plasticity functions can help disentangle drought/variability tolerance versus acquisitive strategies. A better understanding of intraspecific diversity in this grass species will provide more mechanistic insight into its ability to buffer ecosystem changes and provide resiliency in the tallgrass prairie under future droughts.
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Abstract Expression of herbivore defense traits can change dramatically during the course of plant development. Little is known, however, about the degree of genetic or sexual variation in these ontogenetic defense trajectories or whether the trajectories themselves are adaptive, especially in long‐lived species.
We used a 13‐year dataset of chemical defense traits, growth and survivorship from a common garden of trembling aspen (
Populus tremuloides ) genotypes to document long‐term defense trajectories and their relationship to tree fitness during juvenile and early mature stages.Overall, concentrations of the two principal classes of aspen defense compounds (salicinoid phenolic glycosides [SPGs] and condensed tannins [CTs]) decreased to differing degrees in foliage of juvenile trees and then remained relatively constant in maturity. Initial values, juvenile rates of change and average mature values all exhibited significant genetic variation for both SPGs and CTs.
Relationships between defense trajectory parameters and metrics of tree fitness (growth and survivorship) depended on compound type and tree sex. Females with higher‐allocation SPG trajectories (high initial juvenile concentrations, slow juvenile declines, high mature concentrations) grew more slowly relative to females with lower‐allocation trajectories. In males, higher‐allocation SPG trajectories had a lesser effect on growth but were associated with reduced mortality. Juvenile CT trajectories were not correlated with tree fitness, but average CT concentration in maturity was positively related to growth in females.
These results suggest that ontogenetic defense trajectories are adaptive and subject to natural selection. Genotypic variation and ontogeny shape tree defensive chemistry, both independently and interactively. These patterns of defense expression have the potential to structure trophic interactions and the genetic composition of forests in both space and time.
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