Predicting the fate of coastal marshes requires understanding how plants respond to rapid environmental change. Environmental change can elicit shifts in trait variation attributable to phenotypic plasticity and act as selective agents to shift trait means, resulting in rapid evolution. Comparably, less is known about the potential for responses to reflect the evolution of trait plasticity. Here, we assessed the relative magnitude of eco‐evolutionary responses to interacting global change factors using a multifactorial experiment. We exposed replicates of 32 Comparisons of responses to global change factors among age cohorts and across provenances indicated that plasticity has evolved in five of the seven traits measured. Accounting for evolutionary factors (i.e. evolution and sources of heritable variation) in statistical models explained an additional 9–31% of trait variation. Our findings indicate that evolutionary factors mediate ecological responses to environmental change. The magnitude of evolutionary change in plant traits over the last century suggests that evolution could play a role in pacing future ecosystem response to environmental change.
Plants perceive a multitude of environmental signals and stresses, and integrate their response to them in ways that culminate in modified phenotypes, optimized for plant survival. This ability of plants, known as phenotypic plasticity, is found throughout evolution, in all plant lineages. For any given environment, the specifics of the response to a particular signal may vary depending on the plants’ unique physiology and ecological niche. The bryophyte lineage, including mosses, which diverged from the vascular plants ~450–430 million years ago, represent a unique ecological and phylogenetic group in plant evolution. Several aspects of the moss life cycle, their morphology including the presence of specialized tissue types and distinct anatomical features, gene repertoires and networks, as well as the habitat differ significantly from those of vascular plants. To evaluate the outcomes of these differences, we explore the phenotypic responses of mosses to environmental signals such as light, temperature, CO2, water, nutrients, and gravity, and compare those with what is known in vascular plants. We also outline knowledge gaps and formulate testable hypotheses based on the contribution of anatomical and molecular factors to specific phenotypic responses.
more » « less- NSF-PAR ID:
- 10405838
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Journal of Experimental Botany
- Volume:
- 73
- Issue:
- 13
- ISSN:
- 0022-0957
- Format(s):
- Medium: X Size: p. 4514-4527
- Size(s):
- ["p. 4514-4527"]
- Sponsoring Org:
- National Science Foundation
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Abstract Temporal variation is a powerful source of selection on life history strategies and functional traits in natural populations. Theory predicts that the rate and predictability of fluctuations should favor distinct strategies, ranging from phenotypic plasticity to bet-hedging, which are likely to have important consequences for species distribution patterns and their responses to environmental change. To date, we have few empirical studies that test those predictions in natural systems, and little is known about how genetic, environmental, and developmental factors interact to define the “fluctuation niche” of species in temporally variable environments. In this study, we evaluated the effects of hydrological variability on fitness and functional trait variation in three closely related plant species in the genus Lasthenia that occupy different microhabitats within vernal pool landscapes. Using a controlled greenhouse experiment, we manipulated the mean and variability in hydrological conditions by growing plants at different depths with respect to a shared water table and manipulating the magnitude of stochastic fluctuations in the water table over time. We found that all species had similarly high relative fitness above the water table, but differed in their sensitivities to water table fluctuations. Specifically, the two species from vernal pools basins, where soil moisture is controlled by a perched water table, were negatively affected by the stochasticity treatments. In contrast, a species from the upland habitat surrounding vernal pools, where stochastic precipitation events control soil moisture variation, was insensitive to experimental fluctuations in the water table. We found strong signatures of genetic, environmental (plastic), and developmental variation in four traits that can influence plant hydrological responses. Three of these traits varied across plant development and among experimental treatments in directions that aligned with constitutive differences among species, suggesting that multiple sources of variation align to facilitate phenotypic matching with the hydrological environment in Lasthenia. We found little evidence for predicted patterns of phenotypic plasticity and bet-hedging in species and traits from predictable and stochastic environments, respectively. We propose that selection for developmental shifts in the hydrological traits of Lasthenia species has reduced or modified selection for plasticity at any given stage of development. Collectively, these results suggest that variation in species’ sensitivities to hydrological stochasticity may explain why vernal pool Lasthenia species do not occur in upland habitat, and that all three species integrate genetic, environmental, and developmental information to manage the unique patterns of temporal hydrological variation in their respective microhabitats.
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Abstract Plant functional strategies change considerably as plants develop, driven by intraindividual variability in anatomical, morphological, physiological and architectural traits.
Developmental trait variation arises through the complex interplay among genetically regulated phase change (i.e. ontogeny), increases in plant age and size, and phenotypic plasticity to changing environmental conditions. Although spatial drivers of intraspecific trait variation have received extensive research attention, developmentally driven intraspecific trait variation is largely overlooked, despite widespread occurrence.
Ontogenetic trait variation is genetically regulated, leads to dramatic changes in plant phenotypes and evolves in response to predictable changes in environmental conditions as plants develop.
Evidence has accumulated to support a general shift from fast to slow relative growth rates and from shade to sun leaves as plants develop from the highly competitive but shady juvenile niche to the stressful adult niche in the systems studied to date.
Nonetheless, there are major gaps in our knowledge due to examination of only a few environmental factors selecting for the evolution of ontogenetic trajectories, variability in how ontogeny is assigned, biogeographic sampling biases on trees in temperate biomes, dependencies on a few broadly sampled leaf morphological traits and a lack of longitudinal studies that track ontogeny within individuals. Filling these gaps will enhance our understanding of plant functional ecology and provide a framework for predicting the effects of global change threats that target specific ontogenetic stages.
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Summary Extant land plants consist of two deeply divergent groups, tracheophytes and bryophytes, which shared a common ancestor some 500 million years ago. While information about vascular plants and the two of the three lineages of bryophytes, the mosses and liverworts, is steadily accumulating, the biology of hornworts remains poorly explored. Yet, as the sister group to liverworts and mosses, hornworts are critical in understanding the evolution of key land plant traits. Until recently, there was no hornwort model species amenable to systematic experimental investigation, which hampered detailed insight into the molecular biology and genetics of this unique group of land plants. The emerging hornwort model species,
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