Intraspecific Variation In Functional Traits Research Articles

Local adaptation to climate inferred from intraspecific variation in plant functional traits along a latitudinal gradient.

Ascertaining the traits important for acclimation and adaptation is a critical first step to predicting the fate of populations and species facing rapid environmental change. One of the primary challenges in trait-based ecology is understanding the patterns and processes underpinning functional trait variation in plants. Studying intraspecific variation of functional traits across latitudinal gradients offers an excellent in situ approach to assess associations with environmental factors, which naturally covary along these spatial scales such as the local climate and soil profiles. Therefore, we examined how climatic and edaphic conditions varied across a ~160-km latitudinal gradient to understand how these conditions were associated with the physiological performance and morphological expression within five spatially distinct populations spanning the latitudinal distribution of a model species (Stylidium hispidum Lindl.). Northern populations had patterns of trait means reflecting water conservation strategies that included reduced gas exchange, rosette size and floral investment compared to the southern populations. Redundancy analysis, together with variance partitioning, showed that climate factors accounted for a significantly greater portion of the weighted variance in plant trait data (22.1%; adjusted R2= 0.192) than edaphic factors (9.3%; adjusted R2= 0.08). Disentangling such independent and interactive abiotic drivers of functional trait variation will deliver key insights into the mechanisms underpinning local adaptation and population-level responses to current and future climates.

Temperature explains intraspecific functional trait variation in Phragmites australis more effectively than soil properties

Temperature explains intraspecific functional trait variation in Phragmites australis more effectively than soil properties

Intraspecific trait variability facilitates tree species persistence along riparian forest edges in Southern Amazonia

Tropical forest fragmentation from agricultural expansion alters the microclimatic conditions of the remaining forests, with effects on vegetation structure and function. However, little is known about how the functional trait variability within and among tree species in fragmented landscapes influence and facilitate species’ persistence in these new environmental conditions. Here, we assessed potential changes in tree species’ functional traits in riparian forests within six riparian forests in cropland catchments (Cropland) and four riparian forests in forested catchments (Forest) in southern Amazonia. We sampled 12 common functional traits of 123 species across all sites: 64 common to both croplands and forests, 33 restricted to croplands, and 26 restricted to forests. We found that forest-restricted species had leaves that were thinner, larger, and with higher phosphorus (P) content, compared to cropland-restricted ones. Tree species common to both environments showed higher intraspecific variability in functional traits, with leaf thickness and leaf P concentration varying the most. Species turnover contributed more to differences between forest and cropland environments only for the stem-specific density trait. We conclude that the intraspecific variability of functional traits (leaf thickness, leaf P, and specific leaf area) facilitates species persistence in riparian forests occurring within catchments cleared for agricultural expansion in Amazonia.

Variation in Pheidole nodus (Hymenoptera: Formicidae) functional morphology across urban parks.

Habitat fragmentation and consequent population isolation in urban areas can impose significant selection pressures on individuals and species confined to urban islands, such as parks. Despite many comparative studies on the diversity and structure of ant community living in urban areas, studies on ants' responses to these highly variable ecosystems are often based on assemblage composition and interspecific mean trait values, which ignore the potential for high intraspecific functional trait variation among individuals. Here, we examined differences in functional traits among populations of the generalist ant Pheidole nodus fragmented between urban parks. We used pitfall trapping, which is more random and objective than sampling colonies directly, despite a trade-off against sample size. We then tested whether trait-filtering could explain phenotypic differences among urban park ant populations, and whether ant populations in different parks exhibited different phenotypic optima, leading to positional shifts in anatomical morphospace through the regional ant meta-population. Intraspecific morphological differentiation was evident across this urban region. Populations had different convex hull volumes, positioned differently over the morphospace. Fragmentation and habitat degradation reduced phenotypic diversity and, ultimately, changed the morphological optima of populations in this urban landscape. Considering ants' broad taxonomic and functional diversity and their important role in ecosystems, further work over a variety of ant taxa is necessary to ascertain those varied morphological response pathways operating in response to population segregation in urban environments.

Intraspecific functional trait variation in weeds: A strategy in response to competition with crop and weed plants

AbstractWeeds are a key component of agroecosystems and compete with crop plants. Crop‐weed competition has been widely investigated over the past decades, although how functional traits mediate these competitive interactions has rarely been explored. In this study, we measured functional traits in 4400 individual plants belonging to 32 weed species, growing among four crops differing in functional traits. We assessed the intraspecific variation in weed functional traits in response to competition with crops but also with the other weeds. We found that the most abundant weeds have a lower intraspecific trait variability than other weed species for leaf dry matter content (LDMC), but this pattern was not observed for canopy height (CH) nor for specific leaf area (SLA). We found that most of the weed species tended to grow taller and have higher LDMC values when crop CH and LDMC increased. We propose that these species display a ‘crop matching’ strategy, tending to match crop functional trait values in response to competition. We also found that weed‐weed competition affected weed functional traits, sometimes more strongly than crop‐weed competition. This study highlights that intraspecific trait variation is important to consider when investigating the processes underlying weed species community assembly, especially resource competition. Further studies are required to identify the source of intraspecific trait variation in weeds and the consequences for weed fitness.

Intraspecific Variation in Functional Traits of Medicago sativa Determine the Effect of Plant Diversity and Nitrogen Addition on Flowering Phenology in a One-Year Common Garden Experiment.

Nitrogen deposition and biodiversity alter plant flowering phenology through abiotic factors and functional traits. However, few studies have considered their combined effects on flowering phenology. A common garden experiment with two nitrogen addition levels (0 and 6 g N m-2 year-1) and five species richness levels (1, 2, 4, 6, and 8) was established. We assessed the effects of nitrogen addition and plant species richness on three flowering phenological events of Medicago sativa L. via changes in functional traits, soil nutrients, and soil moisture and temperature. The first flowering day was delayed, the last flowering day advanced, and the flowering duration shortened after nitrogen addition. Meanwhile, the last flowering day advanced, and flowering duration shortened along plant species richness gradients, with an average of 0.64 and 0.95 days change per plant species increase, respectively. Importantly, it was observed that plant species richness affected flowering phenology mainly through changes in plant nutrient acquisition traits (i.e., leaf nitrogen and carbon/nitrogen ratio). Our findings illustrate the non-negligible effects of intraspecific variation in functional traits on flowering phenology and highlight the importance of including functional traits in phenological models to improve predictions of plant phenology in response to nitrogen deposition and biodiversity loss.

Decoupling of functional traits from intraspecific patterns of growth and drought stress resistance.

Intraspecific variation in functional traits may mediate tree species' drought resistance, yet whether trait variation is due to genotype (G), environment (E), or G×E interactions remains unknown. Understanding the drivers of intraspecific trait variation and whether variation mediates drought response can improve predictions of species' response to future drought. Using populations of quaking aspen spanning a climate gradient, we investigated intraspecific variation in functional traits in the field as well as the influence of G and E among propagules in a common garden. We also tested for trait-mediated trade-offs in growth and drought stress tolerance. We observed intraspecific trait variation among the populations, yet this variation did not necessarily translate to higher drought stress tolerance in hotter/drier populations. Additionally, plasticity in the common garden was low, especially in propagules derived from the hottest/driest population. We found no growth-drought stress tolerance trade-offs and few traits exhibited significant relationships with mortality in the natural populations, suggesting that intraspecific trait variation among the traits measured did not strongly mediate responses to drought stress. Our results highlight the limits of trait-mediated responses to drought stress and the complex G×E interactions that may underlie drought stress tolerance variation in forests in dry environments.

Leaf functional traits and pathogens: Linking coffee leaf rust with intraspecific trait variation in diversified agroecosystems.

Research has demonstrated that intraspecific functional trait variation underpins plant responses to environmental variability. However, few studies have evaluated how trait variation shifts in response to plant pathogens, even though pathogens are a major driver of plant demography and diversity, and despite evidence of plants expressing distinct strategies in response to pathogen pressures. Understanding trait-pathogen relationships can provide a more realistic understanding of global patterns of functional trait variation. We examined leaf intraspecific trait variability (ITV) in response to foliar disease severity, using Coffea arabica cv. Caturra as a model species. We quantified coffee leaf rust (CLR) severity-a fungal disease prominent in coffee systems-and measured key coffee leaf functional traits under contrasting, but widespread, management conditions in an agroforestry system. We found that coffee plants express significant ITV, which is largely related to shade tree treatment and leaf position within coffee canopy strata. Yet within a single plant canopy stratum, CLR severity increased with increasing resource conserving trait values. However, coffee leaves with visible signs of disease expressed overall greater resource acquiring trait values, as compared to plants without visible signs of disease. We provide among the first evidence that leaf traits are correlated with foliar disease severity in coffee, and that functional trait relationships and syndromes shift in response to increased disease prevalence in this plant-pathogen system. In doing so, we address a vital gap in our understanding of global patterns of functional trait variation and highlight the need to further explore the potential role of pathogens within established global trait relationships and spectra.

Substantial intraspecific trait variation across a hydrological gradient in northern Australian fishes

AbstractTrait‐based models of ecological communities and ecosystem functioning often fail to account for intraspecific variation in functional traits, assuming that intraspecific variability is negligible compared with interspecific variability. However, this assumption remains poorly tested across vertebrate animals where past studies routinely describe species according to mean trait values without explicit consideration of individual trait variability. We assessed nine functional traits for 4254 individuals belonging to 15 freshwater fish species from 11 families in northern Australia, including body elongation, body shape, caudal peduncle throttle, eye size, eye position, gape shape, gape size, mouth position, and pectoral fin length. We quantified the extent and geography of intraspecific trait variability and its relationship with riverine hydrologic regimes using a structured sampling design. Using a combination of single‐ and multi‐trait analyses, we demonstrate that intraspecific trait variability can contribute up to 70% of the total trait variability depending on the attribute considered and averaged 31% across all traits. The magnitude of intraspecific trait variability also varied across the hydrological permanency gradient. Fish assemblages in intermittent streams subjected to frequent environmental disturbance had high intraspecific trait variability, most likely due to strong abiotic filters limiting interspecific divergence. Conversely, assemblages in perennial rivers with less harsh environmental filters but with a larger pool of species expressed lower intraspecific trait variability: This is most likely due to stronger resource competition (biotic filter), which promotes specialization of resource use and, consequently, interspecific divergence. Our study provides the first evidence of intraspecific trait variability driven by a disturbance gradient for an animal group and points to the need for additional research into the functional importance of intraspecific variability in animal ecology. A better understanding of the patterns, drivers, and implications of intraspecific trait variability will help guide mechanistic‐based predictions of the effects of environmental changes on community assemblage and ecosystem processes.

Using intraspecific variation of functional traits and environmental factors to understand the formation of nestedness patterns of a local forest community

Abstract The concept of nestedness originated from the field of biogeography decades ago and has been widely used in metacommunities and biological interaction networks, but there is still a lack of research within local communities. Moreover, studies on nestedness usually rarely incorporate the functional traits of the species and the environmental characteristics of the sites. In this study, we constructed a species presence–absence matrix of a 50-ha forest plot, used the simulated annealing algorithm to reveal the maximum nested structure and further tested the significance of nestedness patterns by constructing null ensembles. The nested ranks were used to represent the orders of species and quadrats in the maximum nestedness matrix. The regression tree analysis was used to reveal the relationships of nested ranks with environmental factors and functional traits. We found that the co-occurrence pattern of local plant communities was significantly nested. The regression tree results showed that the nested ranks of quadrats were determined by soil available phosphorus, soil water content, soil organic carbon and soil pH. Intraspecific variation of functional traits, including leaf C, leaf pH, leaf dry matter content and maximum photosynthetic rate rather than means of functional traits, provided a better explanation for the formation of species’ nested ranks. Understanding the causes of species and quadrats nested ranks provides novel lens and useful insights into ecological processes underlying nestedness, and further improves our knowledge of how local plant communities are assembled.

Plant traits and landscape simplification drive intraspecific trait diversity of Bombus terrestris in wildflower plantings

Wildflower plantings are an important mitigation tool within agri-environmental schemes to counter insect decline in resource-scarce agricultural landscapes. Effectiveness of wildflower plantings for insect conservation is typically studied at the community or species level. It is the individual, however, that is subject to changing abiotic and biotic conditions, not the species per se. Accordingly, functional traits of individuals, i.e., the intraspecific functional diversity within species, likely mediate responses to wildflower resources and landscape context. Here we focused on the ecologically and economically important wild insect pollinator Bombus terrestris to study its intraspecific functional diversity and plant-pollinator individual interactions in wildflower plantings. We found considerable trait variation among flower-visiting B. terrestris workers. Locally, this variation could be attributed to flowering plant traits, with larger workers visiting larger inflorescences and individuals with longer tongues preferentially feeding on zygomorphic but not radially symmetrical flowers. In addition, wildflower plantings with high floral abundance attracted individuals with larger pollen baskets. At the landscape scale, increasing proportion of arable land resulted in smaller B. terrestris individuals in wildflower plantings, and a decrease in the overall size diversity of workers. These findings highlight the so far little considered role of intraspecific variation in functional traits of wild pollinators, which can mediate the trait-matching between plants and pollinator individuals. Landscape simplification from agriculture threatens intraspecific pollinator diversity, with potential harmful effects for pollinator fitness and plant reproduction. Tailored wildflower plantings can thus serve as an important tool to increase intraspecific variation in simplified landscapes. When designing seed mixtures for these plantings, high complementarity in plant traits is key for promoting high intraspecific trait diversity of bumblebees and potentially of other associated insect species.

The intraspecific variation of functional traits modulates drought resilience of European beech and pubescent oak

Abstract A higher frequency and intensity of droughts will impair forest productivity. Therefore, improving our understanding of which factors enhance tree growth resilience against drought has become a crucial issue, but we lack information at the intraspecific level. In this study, we investigate the role played by climatic conditions and tree characteristics in the growth response to severe droughts in two deciduous Fagaceae species near their southern distribution limit: the temperate European beech Fagus sylvatica and the Mediterranean pubescent oak Quercus pubescens. The study area is located in Catalonia, NE Spain, where 149 trees were cored covering the water availability gradient of the species in the region. In addition, tree size (diameter and height) and an ensemble of stem, leaf and hydraulic traits were collected for each tree. Growth responses to extreme droughts during the period 1980–2015 were assessed using resilience indicators based on residual basal area increment series predicted by a model including growing season water balance. Although resistance was unrelated to drought intensity, higher water availability improved recovery and reduced drought legacy effects. Taller trees showed higher resilience against drought, which could be explained by the relationship between the variation in tree height and functional traits, such as leaf nitrogen concentration, leaf turgor loss point and resistance to xylem embolism. For both species, trees with lower cavitation resistance, higher leaf nitrogen concentration and tighter stomatal regulation (suggested by less negative turgor loss point and carbon isotope composition) displayed better performance during and after severe droughts. Both species showed a progressive decrease in resilience and increase in legacy effects. Synthesis. This study highlights the relevance of analysing intraspecific variation of functional traits involved in tree water and carbon balance to improve our understanding of the resilience and variability of growth responses to drought within species.

Plant age affects intraspecific variation in functional traits

Functional traits are often used to examine ecological patterns and processes. Ontogeny—changes that occur over time as the result of development—generates variation in traits within individual organisms. We aimed to quantify the role of ontogeny in structuring functional trait variation across a range of co-existing herbaceous perennial species and hypothesized that ontogenetic variation in traits would be greater in younger vs. older plants. We grew eight herbaceous perennial forb species common in tallgrass prairies from seed in a greenhouse in Madison, Wisconsin, USA to determine how and when time-related variation in functional traits is large relative to other sources of variation, such as differences between leaves and species. We destructively measured common functional traits on four individuals of each species every two weeks for 19 weeks, including leaf mass fraction, root mass fraction, stem mass fraction, specific leaf area, leaf dry matter content, and leaf area. We found that most functional traits indeed change through time, that the direction of many changes are consistent between species but the magnitude of change is species specific, and most time-related variation occurred earlier in development. These results emphasize the importance of considering sampling timing and differences between young and old plants when measuring functional traits. Our results suggest that ontogenetic intraspecific variation can be substantial, especially early in life. It may be problematic to use traits measured from mature plants to interpret the importance of processes that occur at earlier life stages or vice versa; using seedling traits to understand adult plant responses may also be inappropriate.

Coordination of stem and leaf traits define different strategies to regulate water loss and tolerance ranges to aridity.

Adaptation to drought involves complex interactions of traits that vary within and among species. To date, few data are available to quantify within-species variation in functional traits and they are rarely integrated into mechanistic models to improve predictions of species response to climate change. We quantified intraspecific variation in functional traits of two Hakea species growing along an aridity gradient in southeastern Australia. Measured traits were later used to parameterise the model SurEau to simulate a transplantation experiment to identify the limits of drought tolerance. Embolism resistance varied between species but not across populations. Instead, populations adjusted to drier conditions via contrasting sets of trait trade-offs that facilitated homeostasis of plant water status. The species from relatively mesic climate, Hakea dactyloides, relied on tight stomatal control whereas the species from xeric climate, Hakea leucoptera dramatically increased Huber value and leaf mass per area, while leaf area index (LAI) and epidermal conductance (gmin ) decreased. With trait variability, SurEau predicts the plasticity of LAI and gmin buffers the impact of increasing aridity on population persistence. Knowledge of within-species variability in multiple drought tolerance traits will be crucial to accurately predict species distributional limits.

Phenology determines leaf functional traits across Rhododendron species in the Sikkim Himalaya

Elevation gradients provide an ideal setting to infer species' functional trait responses to predicted future climate change. In plants, leaf functional traits help assess their capacity to cope with varying resources. Variation in abiotic conditions over short vertical distances can influence plant phenology, particularly leafing and flowering durations, and leaf functional traits at both inter- and intra-specific levels. However, studies examining relationships between leaf functional traits and phenology duration along elevation gradients are limited. We tested the relationship between leaf size, leaf thickness, specific leaf area, and leafing durations in 10 Rhododendron species in the Sikkim Himalaya. All the investigated traits varied significantly across species, but intra-specific variation in functional traits was observed only among a few. Leaf size and thickness showed significant negative relationships with elevation and a comparative phylogenetic method exhibited a strong relationship between leaf traits and leafing duration. We observed higher leaf thickness and size in species with longer leafing durations and less overlap in leafing and flowering durations. In contrast, species with shorter leafing durations and relatively more overlap in their flowering and leafing durations showed lower leaf thickness and leaf size. Leaf traits such as leaf thickness and leaf size also exhibited a strong phylogenetic signal across 10 Rhododendron species. Overall, from our findings, we infer that along an elevation gradient, the magnitude of leaf trait responses to future increases in temperature may vary depending on species phenology durations and phylogeny.

桂林岩溶石山青冈群落植物功能性状的种间和种内变异研究

研究植物功能性状的种间和种内变异，有助于揭示植物对环境的适应策略及其群落构建机制研究。以桂林岩溶石山青冈群落主要木本植物为研究对象，选取叶干物质含量（LDMC）、叶厚度（LT）、比叶面积（SLA）和木材密度（WD）4个功能性状，采用混合线性模型结合方差分解方法对其在种内和种间尺度的变异程度和相对贡献进行分析，同时运用零模型方法探讨驱动岩溶石山青冈群落构建的潜在机制。结果表明：（1） LDMC，LT，SLA和WD这4个性状在种内和种间水平上均存在不同程度的变异幅度，种间变异大于种内变异，但种内变异亦不容忽略。（2）零模型检验表明，将种内变异纳入考虑的环境过滤检测得到改善，基于个体性状值的尺度考虑群落构建机制研究是必要的。（3）对于桂林岩溶石山青冈群落，环境过滤作用确实是群落构建的重要驱动机制，与相似性限制作用和随机作用共同塑造了以青冈为优势物种的群落构建。;Interspecific and intraspecific variations of plant functional traits help reveal plant adaptation strategies to the environment and to mechanism of community assembly. In this study, we investigated 4 key functional traits of 105 species and 4190 individuals to understand changes in woody plant functional traits of the Cyclobalanopsis glauca community in the karst area, Guilin city. These functional traits were leaf dry matter content (LDMC), leaf thickness (LT), specific leaf area (SLA), and wood density (WD). Combined with the variance decomposition method, we performed the mixed linear models to analyze the degree and proportion of interspecific and intraspecific variation of functional traits. Based on it, we used the null model method to detect the potential driving mechanism in community construction by considering or not considering the variability of intraspecific variation of functional traits. These results suggest that:(1) the variation of the four plant functional traits was dominated by interspecific variation, and the intraspecific variation cannot be ignored. (2) The nullmodel test shows that the environmental filtering test at the individual level is improved. Community assembly seems to affect traits on the scale of individuals. (3) For the Cyclobalanopsis glauca community in the karst area of Guilin city, environmental filtering is indeed an important driving mechanism for community assembly. Together with similarity restriction and random effects, it shapes the community construction with Cyclobalanopsis as the dominant species.

Mapping functional diversity using individual tree-based morphological and physiological traits in a subtropical forest

Functional diversity (FD) provides a link between biodiversity and ecosystem functioning, summarizing inter- and intra-specific variation of functional traits. However, quantifying plant traits and FD consistently and cost-effectively across large and heterogeneous forest areas is challenging with traditional field sampling. Airborne light detection and ranging (LiDAR) and imaging spectroscopy provide spatially explicit data, which allow mapping of selected forest traits and FD at different spatial scales. We develop an individual tree-based method to measure forest FD from tree neighborhoods to whole forests, and demonstrate the approach by mapping functional traits of over one million trees in a subtropical forest in China. We retrieved canopy morphological traits (95th quantile height, leaf area index and foliage height diversity) and physiological traits (proxies of nitrogen, carotenoids and specific leaf area) for each individual canopy tree crown from LiDAR and imaging spectroscopy data, respectively. Based on the multivariate trait space spanned by the six trait axes and filled by measured tree individuals, we mapped forest FD as richness, divergence and evenness, and explored spatial patterns of FD as well as FD–area and FD–tree number relationships. The results show that LiDAR-derived morphological traits and spectral indices of physiological traits are consistent with field measurements and show weak correlations between each other at individual tree level. Morphological functional richness follows a hump-shaped pattern along the elevational gradient of 984–1805 m, with maximum values at elevations around 1450 m, while high physiological functional richness occurs at medium and high elevations. At an ecosystem scale of 30 × 30 m, morphological richness increases continuously with tree density, but physiological richness decreases again at very high densities. Moreover, functional richness shows a logarithmic relationship with increasing area or number of individual trees, and local trait convergence is predominant in our study area. We demonstrate the ability to quantify FD using morphological and physiological traits by remote sensing, which provides a pathway to conduct individual-level trait-based ecology with wall-to-wall data.

Along with intraspecific functional trait variation, individual performance is key to resolving community assembly processes

Abstract Species contributing high proportions to community biomass strongly influence ecosystem processes within the community. Studies have shown that dominant species may serve as nurse plants, helping to ensure biomass stability of the subordinate species under stress conditions. The question is widely debated as to whether either niche differentiation or neutral processes drive the net outcome of plant interactions within a subordinate plant community. To answer this question, requires precise estimates of individual variation in functional traits and performance. In a 5‐year mesocosm experiment, the functional responses of a subordinate plant community to the removal of the dominant species were evaluated across two drought‐stress scenarios. Small‐scale (i.e. large pots) wetland communities were constructed comprising one dominant species Carex elata and three subordinate species. Removal of the dominant species allowed evaluation of the net effects of drought and interspecific interactions. We estimated the functional divergences for three traits (SLA, leaf dry matter content and allocation to height growth) and compared these with performance differences quantified individually. This enabled distinctions to be made between deterministic (i.e. niche differentiation) and neutral processes driving the drought response of the subordinate community. We showed that the dominant species decreased relative performance differences within the subordinate plant community under conditions of permanent drought stress. These changes were associated with the convergence of traits related to resource acquisition and growth. The dominant species equalized species performance differences by supressing relatively drought‐tolerant species with low competitive ability and by supporting the less drought‐tolerant species with relatively high competitive ability. Meanwhile, under conditions of inter‐annual drought, the subordinate species likely coexisted due to differentiation in resource‐use strategies and the interaction with the dominant species. Inclusion of individual variation in performance with a functional trait approach provides valuable insights into the processes structuring plant communities. Ours is the first study to provide evidence that subordinate species exposed to drought may coexist via neutral processes arising from their interactions with the dominant species, leading to functional convergence of traits associated with the trade‐off between stress tolerance and competitive ability. A free Plain Language Summary can be found within the Supporting Information of this article.

Aridity drives coordinated trait shifts but not decreased trait variance across the geographic range of eight Australian trees.

Large intraspecific functional trait variation strongly impacts many aspects of communities and ecosystems, and is the medium upon which evolution works. Yet intraspecific trait variation is inconsistent and hard to predict across traits, species and locations. We measured within-species variation in leaf mass per area (LMA), leaf dry matter content (LDMC), branch wood density (WD), and allocation to stem area vs leaf area in branches (branch Huber value (HV)) across the aridity range of seven Australian eucalypts and a co-occurring Acacia species to explore how traits and their variances change with aridity. Within species, we found consistent increases in LMA, LDMC and WD and HV with increasing aridity, resulting in consistent trait coordination across leaves and branches. However, this coordination only emerged across sites with large climate differences. Unlike trait means, patterns of trait variance with aridity were mixed across populations and species. Only LDMC showed constrained trait variation in more xeric species and drier populations that could indicate limits to plasticity or heritable trait variation. Our results highlight that climate can drive consistent within-species trait patterns, but that patterns might often be obscured by the complex nature of morphological traits, sampling incomplete species ranges or sampling confounded stress gradients.

Intraspecific variation in Phragmites australis: Clinal adaption of functional traits and phenotypic plasticity vary with latitude of origin

Abstract Widespread plant species generally have high intraspecific variation in functional traits, which is reflected in their great variety of phenotypes. This variety can result from both genetic differences due to local adaptation and phenotypic plasticity. With high intraspecific variation and nearly global distribution, the common reed Phragmites australis is a suitable model species for studying the underlying mechanisms of intraspecific trait variation. In this study, 71 genotypes of P. australis from seven phylogeographic groups were transplanted into two replicate common gardens located in very different climates: northern Europe and mid‐east Asia. We measured seven functional traits of all these genotypes over the growing season, including shoot height, maximum biomass per shoot, shoot density, node number per stem, leaf life span, flowering occurrence and flowering date. Our aim was to assess the relative effects of genetic (phylogeographic origin) and environmental (common garden) status, and interactions between them, on intraspecific variation in functional traits of P. australis. We found common garden having the strongest influence on most functional traits studied. All traits except flowering occurrence varied significantly across gardens, revealing the important role of phenotypic plasticity on trait variation in P. australis. We also found significant differences in trait variation among the different phylogeographic groups of P. australis and, thus, evidence for genetically determined intraspecific variation in the morphological and life‐history traits addressed in this study. All functional traits showed significant (p ≤ 0.0054), albeit minor to moderately explained (R2 ≤ 0.57), latitudinal patterns in both gardens. Covariation of multiple traits was similar in the two gardens. Phenotypic plasticity was trait‐ specific, and the plasticity of shoot height and maximum biomass per shoot increased towards higher latitude of genotypic origin. Our results indicate that the latitude of origin affects the evolution of functional traits, as well as their phenotypic plasticity. Since phenotypic plasticity is a crucial mechanism for acclimation and evolution, our findings support the role of gene‐based adaptive phenotypic plasticity in plant evolution. The intraspecific spatial variation in functional traits and their phenotypic plasticity can help predict species distribution, persistence and invasion under global climate change.