An official website of the United States government
Summary Variation in leaf venation network architecture may reflect trade‐offs among multiple functions including efficiency, resilience, support, cost, and resistance to drought and herbivory. However, our knowledge about architecture‐function trade‐offs is mostly based on studies examining a small number of functional axes, so we still lack a more integrative picture of multidimensional trade‐offs.Here, we measured architecture and functional traits on 122 ferns and angiosperms species to describe how trade‐offs vary across phylogenetic groups and vein spatial scales (small, medium, and large vein width) and determine whether architecture traits at each scale have independent or integrated effects on each function.We found that generalized architecture‐function trade‐offs are weak. Architecture strongly predicts leaf support and damage resistance axes but weakly predicts efficiency and resilience axes. Architecture traits at different spatial scales contribute to different functional axes, allowing plants to independently modulate different functions by varying network properties at each scale.This independence of vein architecture traits within and across spatial scales may enable evolution of multiple alternative leaf network designs with similar functioning.
more »
« less
The determination of leaf size on the basis of developmental traits
Summary Mature leaf area (LA) is a showcase of diversity – varying enormously within and across species, and associated with the productivity and distribution of plants and ecosystems. Yet, it remains unclear how developmental processes determine variation in LA.We introduce a mathematical framework pinpointing the origin of variation in LA by quantifying six epidermal ‘developmental traits’: initial mean cell size and number (approximating values within the leaf primordium), and the maximum relative rates and durations of cell proliferation and expansion until leaf maturity. We analyzed a novel database of developmental trajectories of LA and epidermal anatomy, representing 12 eudicotyledonous species and 52 Arabidopsis experiments.Within and across species, mean primordium cell number and maximum relative cell proliferation rate were the strongest developmental determinants of LA. Trade‐offs between developmental traits, consistent with evolutionary and metabolic scaling theory, strongly constrain LA variation. These include trade‐offs between primordium cell number vs cell proliferation, primordium mean cell size vs cell expansion, and the durations vs maximum relative rates of cell proliferation and expansion. Mutant and wild‐type comparisons showed these trade‐offs have a genetic basis in Arabidopsis.Analyses of developmental traits underlying LA and its diversification highlight mechanisms for leaf evolution, and opportunities for breeding trait shifts.
more »
« less
- PAR ID:
- 10617626
- Publisher / Repository:
- New Phytologist
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 246
- Issue:
- 2
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- 461 to 480
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Understanding the mechanisms that promote the coexistence of hundreds of species over small areas in tropical forest remains a challenge. Many tropical tree species are presumed to be functionally equivalent shade tolerant species but exist on a continuum of performance trade‐offs between survival in shade and the ability to quickly grow in sunlight. These trade‐offs can promote coexistence by reducing fitness differences.Variation in plant functional traits related to resource acquisition is thought to predict variation in performance among species, perhaps explaining community assembly across habitats with gradients in resource availability. Many studies have found low predictive power, however, when linking trait measurements to species demographic rates.Seedlings face different challenges recruiting on the forest floor and may exhibit different traits and/or performance trade‐offs than older individuals face in the eventual adult niche. Seed mass is the typical proxy for seedling success, but species also differ in cotyledon strategy (reserve vs. photosynthetic) or other leaf, stem and root traits. These can cause species with the same average seed mass to have divergent performance in the same habitat.We combined long‐term studies of seedling dynamics with functional trait data collected at a standard life‐history stage in three diverse neotropical forests to ask whether variation in coordinated suites of traits predicts variation among species in demographic performance.Across hundreds of species in Ecuador, Panama and Puerto Rico, we found seedlings displayed correlated suites of leaf, stem, and root traits, which strongly correlated with seed mass and cotyledon strategy. Variation among species in seedling functional traits, seed mass, and cotyledon strategy were strong predictors of trade‐offs in seedling growth and survival. These results underscore the importance of matching the ontogenetic stage of the trait measurement to the stage of demographic dynamics.Our findings highlight the importance of cotyledon strategy in addition to seed mass as a key component of seed and seedling biology in tropical forests because of the contribution of carbon reserves in storage cotyledons to reducing mortality rates and explaining the growth‐survival trade‐off among species.Synthesis: With strikingly consistent patterns across three tropical forests, we find strong evidence for the promise of functional traits to provide mechanistic links between seedling form and demographic performance.more » « less
-
The interspecific trade‐off between growth versus mortality rates of tree species is thought to be driven by functional biology and to contribute to species ecological niche differentiation. Yet, functional trait variation is often not strongly correlated with growth and mortality, and few studies have investigated the relationships of both traits and niches, specifically encompassing above and belowground resources, to the trade‐off itself. These relationships are particularly relevant for seedlings, which must often survive resource limitation to reach larger size classes.We investigated the functional basis of the interspecific growth–mortality trade‐off and its relationship with ecological niches for seedlings of 14 tree species in a tropical forest in southwest China.We found evidence for an interspecific growth–mortality trade‐off at the seedling stage using 15 functional traits and 15 ecological niche variables. None of the organ‐level traits correlated with growth, mortality, nor the trade‐off, whereas specific stem length (SSL), a biomass allocation trait, was the only trait to have a significant correlation (positive). Moreover, light‐defined niches were not correlated with growth, mortality or the trade‐off, but soil‐defined niches did. Species at the faster growth/higher mortality end of the trade‐off were associated with higher fertility defined by lower soil bulk density and slope, and higher soil organic matter concentration and soil total nitrogen.Our findings indicate the importance of stem elongation and soil fertility for growth, mortality and their trade‐off at the seedling stage in this Asian tropical forest. Our findings contrast with analogous studies in neotropical forests showing the importance of photosynthesis‐related leaf traits related to insolation. Therefore, the functional drivers of demographic rates and trade‐offs, as well as their consequences for ecological niches, can vary among forests, likely owing to differences in biogeography, canopy disturbance rates, topography and soil properties. Moreover, the effects of functional trait variation on demographic rates and trade‐offs may be better revealed when biomass allocation is accounted for in a whole‐plant context. Read the freePlain Language Summaryfor this article on the Journal blog.more » « less
-
Abstract Roots are essential to the diversity and functioning of plant communities, but trade‐offs in rooting strategies are still poorly understood.We evaluated existing frameworks of rooting strategy trade‐offs and tested their underlying assumptions, guided by the hypothesis that community‐level rooting strategies are best described by a combination of variation in organ‐level traits, plant‐level root:shoot allocation and symbiosis‐level mycorrhizal dependency. We tested this hypothesis using data on plant community structure, above‐ and below‐ground biomass, eight root traits including mycorrhizal colonisation and soil properties from an edaphic gradient driven by elevation and water availability in sandhills prairie, Nebraska, USA.We found multidimensional trade‐offs in rooting strategies represented by a two‐way productivity‐durability trade‐off axis (captured by root length density and root dry matter content) and a three‐way resource acquisition trade‐off between specific root length, root:shoot mass ratio and mycorrhizal dependence. Variation in rooting strategies was driven to similar extents by interspecific differences and intraspecific responses to soil properties.Organ‐level traits alone were insufficient to capture community‐level trade‐offs in rooting strategies across the edaphic gradient. Instead, trait variation encompassing organ, plant and symbiosis levels revealed that consideration of whole‐plant phenotypic integration is essential to defining multidimensional trade‐offs shaping the functional variation of root systems. Read the freePlain Language Summaryfor this article on the Journal blog.more » « less
-
Abstract Ecological theory predicts that herbivory should be weaker on islands than on mainland based on the assumption that islands have lower herbivore abundance and diversity. However, empirical tests of this prediction are rare, especially for insect herbivores, and those few tests often fail to address the mechanisms behind island–mainland divergence in herbivory. In particular, past studies have not addressed the relative contribution of top‐down (i.e. predator‐driven) and bottom‐up (i.e. plant‐driven) factors to these dynamics.To address this, we experimentally excluded insectivorous vertebrate predators (e.g. birds, bats) and measured leaf traits associated with herbivory in 52 populations of 12 oak (Quercus) species in three island–mainland sites: The Channel Islands of California vs. mainland California, Balearic Islands vs. mainland Spain, and the island Bornholm vs. mainland Sweden (N = 204 trees). In each site, at the end of the growing season, we measured leaf damage by insect herbivores on control vs. predator‐excluded branches and measured leaf traits, namely: phenolic compounds, specific leaf area, and nitrogen and phosphorous content. In addition, we obtained climatic and soil data for island and mainland populations using global databases. Specifically, we tested for island–mainland differences in herbivory, and whether differences in vertebrate predator effects or leaf traits between islands and mainland contributed to explaining the observed herbivory patterns.Supporting predictions, herbivory was lower on islands than on mainland, but only in the case of Mediterranean sites (California and Spain). We found no evidence for vertebrate predator effects on herbivory on either islands or mainland in any study site. In addition, while insularity affected leaf traits in some of the study sites (Sweden‐Bornholm and California), these effects were seemingly unrelated to differences in herbivory.Synthesis. Our results suggest that vertebrate predation and the studied leaf traits did not contribute to island–mainland variation patterns in herbivory, calling for more nuanced and comprehensive investigations of predator and plant trait effects, including measurements of other plant traits and assessments of predation by different groups of natural enemies.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/nph.20461
