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Background and Aims Genome size is an important plant trait, with substantial interspecies variation. The mechanisms and selective pressures underlying genome size evolution are important topics in evolutionary biology. There is considerable diversity in Allium from the Qinghai–Tibetan Plateau, where genome size variation and related evolutionary mechanisms are poorly understood. Methods We reconstructed the Allium phylogeny using DNA sequences from 71 species. We also estimated genome sizes of 62 species, and determined chromosome numbers in 65 species. We examined the phylogenetic signal associated with genome size variation, and tested how well the data fit different evolutionary models. Correlations between genome size variations and seed mass, altitude and 19 bioclimatic factors were determined. Key Results Allium genome sizes differed substantially between species and within diploids, triploids, tetraploids, hexaploids and octaploids. Size per monoploid genome (1Cx) tended to decrease with increasing ploidy levels. Allium polyploids tended to grow at a higher altitude than diploids. The phylogenetic tree was divided into three evolutionary branches. The genomes in Clade I were mostly close to the ancestral genome (18.781 pg) while those in Clades II and III tended to expand and contract, respectively. A weak phylogenetic signal was detected for Allium genome size. Furthermore, significant positive correlations were detected between genome size and seed mass, as well as between genome size and altitude. However, genome size was not correlated with 19 bioclimatic variables. Conclusions Allium genome size shows gradual evolution, followed by subsequent adaptive radiation. The three well-supported Allium clades are consistent with previous studies. The evolutionary patterns in different Allium clades revealed genome contraction, expansion and relative stasis. The Allium species in Clade II may follow adaptive radiation. The genome contraction in Clade III may be due to DNA loss after polyploidization. Allium genome size might be influenced by selective pressure due to the conditions on the Qinghai–Tibetan Plateau (low temperature, high UV irradiation and abundant phosphate in the soil). [ABSTRACT FROM AUTHOR]

Predictions of how vegetation responds to spatial and temporal differences in climate rely on established links with plant functional traits and vegetation types that can be encoded into Dynamic Global Vegetation Models. Individual traits have been linked to climate at species level and at community level within regions. However, a recent global assessment of aggregated community level traits found unexpectedly weak links with macroclimate, bringing into question broadscale trait–climate associations and implicating local-scale environmental differences in the filtering of communities. To further evaluate patterns in light of these somewhat contradictory results, we quantified the power of macro-environmental variables to explain aggregated plant community traits, taking advantage of new trait data for leaf area, plant height and seed mass combined with a national survey that records cover-abundance using consistent methods for a large number of plots across Australia. In contrast to the global study, we found that abundance-weighted community mean and variance of leaf area and maximum height were correlated with macroclimate. Height and leaf area were highest in wet (especially warm, wet) environments, with actual evapotranspiration explaining 30% of variation in leaf area and 26% in maximum height. Seed mass was weakly related to environment, with no variable explaining more than 5% of variance. Considering all three traits together in a redundancy analysis, the complete set of environmental variables explained 43% of variation in site-mean traits and 29% of within-site trait variance. While significant trait variation remains unexplained, the trait–environment relationships reported here suggest climatically-driven filtering plays a strong role in assembling these vegetation communities. Regional assessments using standardised species abundances can therefore be used to predict aspects of vegetation function. Our quantification of plant community trait patterns along macroclimatic gradients at continental scale thereby contributes a much-needed functional basis for Australian vegetation.

Although plant clonality is an important reproductive strategy complementing seed reproduction, their interrelationship is seldom studied. We evaluated how plant clonality, together with plant economics spectrum and architectural constraints, affect the generative reproduction characteristics of co-existing grassland species. For this purpose, we collected data on seed number, seed mass and seed yield (seed mass x seed number) per shoot of 56 herbaceous species from temperate grasslands in the White Carpathian Mts. (SE Czech Republic).Clonality had a weaker effect on seed traits than leaf economics and plant architecture. Metamer size showed the strongest relationship to seed number per shoot, while leaf dry matter content and canopy height were the most important factors affecting average seed mass in the studied species. Seed yield was affected by both leaf nitrogen and metamer size but only for plants with long lived shoots (di- and polycyclic). The negative correlation between seed mass and seed number per shoot for our dataset was confirmed.Our study did not support the idea that clonality is the most important factor affecting seed production in grassland species and pointed out complex relationships of coordinated traits in coexisting species.

Despite the importance of life-history characteristics in determining a species' success, we still lack basic information about some fundamental life-history elements found across the life cycle of introduced plants. Our study assesses rapid evolutionary divergence in life-history characteristics of the beach daisy Arctotheca populifolia by comparing introduced Australian and source South African plants and measuring eight key variables including seed mass, germination, reproductive output and survival. This is the first study that compares the life history of an introduced plant species with its single original source population, providing a precise and powerful method for detecting evolutionary divergence. We found that introduced A. populifolia has evolved a suite of weedy life-history characteristics in less than 90 years: the introduced plants use a live-fast die-young strategy of germination and survival and produce significantly more inflorescences and more seeds that germinate faster. This knowledge adds to the remarkable data that we already have on the rapid evolutionary divergence occurring in the morphology, physiology and defence of this introduced plant and highlights the speed and scope of evolutionary divergence possible in plants. To fully understand and manage the future of our plant species, we must consider their potential for ongoing change in key aspects of life history. [ABSTRACT FROM AUTHOR]

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Within-species variation is a key component of biodiversity and linking it to climatic gradients may significantly improve our understanding of ecological processes. High variability can be expected in plant traits, but it is unclear to which extent it varies across populations under different climatic conditions. Here, we investigated seed trait variability and its environmental dependency across a latitudinal gradient of two widely distributed duneengineering species (Thinopyrum junceum and Calamagrostis arenaria). Seed germination responses against temperature and seed mass were compared within and among six populations exposed to a gradient of temperature and precipitation regimes (Spiekeroog, DE; Bordeaux, FR; Valencia, ES; Cagliari, IT, Rome, IT; Venice, IT). Seed germination showed opposite trends in response to temperature experienced during emergence in both species: with some expectation, in populations exposed to severe winters, seed germination was warm-cued, whereas in populations from warm sites with dry summer, seed germination was cold-cued. In C. arenaria, variability in seed germination responses disappeared once the seed coat was incised. Seed mass from sites with low precipitation was smaller than that from sites with higher precipitation and was better explained by rainfall continentality than by aridity in summer. Within-population variability in seed germination accounted for 5 to 54%, while for seed mass it was lower than 40%. Seed trait variability can be considerable both within- and among-populations even at broad spatial scale. The variability may be hardly predictable since it only partially correlated with the analyzed climatic variables, and with expectation based on the climatic features of the seed site of origin. Considering seed traits variability in the analysis of ecological processes at both within- and amongpopulation levels may help elucidate unclear patterns of species dynamics, thereby contributing to plan adequate measures to counteract biodiversity loss. [ABSTRACT FROM AUTHOR]

Seed germination traits were assessed on Pinus heldreichii H. Christ, a Tertiary relict, high-elevation Mediterranean pine, endemic in the western Balkan Peninsula and southern Italy; it is naturally grown at the northern Greece mountains, but also found in shrubby form above the timberline. Closed and mature cones were collected (October) for three consecutive years from Pindos Range and Mt. Olympus populations. Cone and seed morphological traits were recorded along with the seedling cotyledon number. Seed germination tests were performed under various ecologically meaningful temperatures and light regimes; climate change effects on seed germination and seedling development were assessed based on two climate scenarios. Final seed germination was moderate (~55%) on both, untreated seed lots at most favourable conditions (15 and 20 °C). Although cold stratification is not an absolute requirement, seed germination rate and final percentage are promoted by both a month of cold stratification (at least 30 or 45 days) and white light. The predicted climate change suggests that a prolonged drought period (>3 months) might turn out by the end of the century in the populations studied. Although the temperature increase might not have significant effects in the germination window of the species. The rainfall decrease will inevitably expose the young seedlings to the summer drought, thus increasing the potential mortality rate. Both ex situ (e.g., germplasm conservation) and in situ measures of conservation are recommended for the species survival in Greece, with a particular focus on the populations established at lower altitudes. [ABSTRACT FROM AUTHOR]

Background and Aims: Rock outcrop vegetation is distributed worldwide and hosts a diverse and unique flora that evolved under harsh environmental conditions. Unfortunately, seed ecology in such ecosystems has received little attention, especially regarding seed traits, germination responses to abiotic factors and the potential role of phylogenetic relatedness on such features Here, we provide the first quantitative and phylogenetically-informed synthesis of the seed functional ecology of Brazilian rock outcrop vegetation, with a particular focus on quartzitic and ironstone campo rupestre., Methods: Using a database of functional trait data, we calculated the phylogenetic signal of seven seed traits for 371 taxa and tested whether they varied among growth forms, geographic distribution, and microhabitats. We also conducted meta-analyses that included 4,252 germination records for 102 taxa to assess the effects of light, temperature, and fire-related cues on the germination of campo rupestre species and explored how the aforementioned ecological groups and seed traits modulate germination responses., Key Results: All traits and germination responses showed a moderate-to-strong phylogenetic signal. Campo rupestre species responded positively to light and had maximum germination between 20-25 ºC. The effect of temperatures beyond this range was moderated by growth form, species geographic distribution, and microhabitat. Seeds exposed to heat shocks above 80 °C lost viability, but smoke accelerated germination. We found a moderating effect of seed mass for in responses to light and heat shocks, with larger, dormant seeds tolerating heat better but less sensitive to light. Species from xeric habitats evolved phenological strategies to synchronise germination during periods of increased soil water availability., Conclusions: Phylogenetic relatedness plays a major role in shaping seed ecology of Brazilian rock outcrop vegetation. Nevertheless, seed traits and germination responses varied significantly between growth forms, species geographic distribution and microhabitats, providing support to the regeneration niche hypothesis and the role of functional traits in shaping germination in these ecosystems., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Within-species variation is a key component of biodiversity and linking it to climatic gradients may significantly improve our understanding of ecological processes. High variability can be expected in plant traits, but it is unclear to which extent it varies across populations under different climatic conditions. Here, we investigated seed trait variability and its environmental dependency across a latitudinal gradient of two widely distributed dune-engineering species (Thinopyrum junceum and Calamagrostis arenaria). Seed germination responses against temperature and seed mass were compared within and among six populations exposed to a gradient of temperature and precipitation regimes (Spiekeroog, DE; Bordeaux, FR; Valencia, ES; Cagliari, IT, Rome, IT; Venice, IT). Seed germination showed opposite trends in response to temperature experienced during emergence in both species: with some expectation, in populations exposed to severe winters, seed germination was warm-cued, whereas in populations from warm sites with dry summer, seed germination was cold-cued. In C. arenaria, variability in seed germination responses disappeared once the seed coat was incised. Seed mass from sites with low precipitation was smaller than that from sites with higher precipitation and was better explained by rainfall continentality than by aridity in summer. Within-population variability in seed germination accounted for 5 to 54%, while for seed mass it was lower than 40%. Seed trait variability can be considerable both within- and among-populations even at broad spatial scale. The variability may be hardly predictable since it only partially correlated with the analyzed climatic variables, and with expectation based on the climatic features of the seed site of origin. Considering seed traits variability in the analysis of ecological processes at both within- and among-population levels may help elucidate unclear patterns of species dynamics, thereby contributing to plan adequate measures to counteract biodiversity loss.

In many invaded grasslands, dominant exotic species can produce large amounts of litter that modify local abiotic conditions and species' interactions. These novel conditions can reduce native species abundance and promote the persistence of exotic species, yet the strength of this disparity may be influenced by how consumer pressure interacts with litter accumulation. Consumers may exacerbate this disparity by preferentially targeting native species or by promoting heterogeneity in microhabitats due to their movement and small‐scale ground disturbances that favours fast growing exotic species. How species respond to litter accumulation and consumer pressure may depend on either evolutionary differences, whereby exotics species may benefit from a lack natural predators, or by functional differences, in which species' physiological traits may confer fitness advantages to low‐light conditions or herbivory or granivory pressure.We examined the impact of litter presence and small mammal herbivory on the establishment and reproduction of functionally diverse exotic versus native species seeded across sites that naturally vary in resource availability in an annual invaded California grassland. We assessed whether seed mass and leaf nitrogen content (LNC) were predictive of successful establishment and reproduction.Litter accumulation affected exotic and native species differently, with litter significantly decreasing native recruitment and reproduction, while exotics were largely unaffected. Small mammals had a slight positive effect on the establishment of native species when litter was present but did not influence exotic species. Regardless of species provenance, larger seeded species established at a higher density while species with lower leaf nitrogen content had a higher density of reproductive individuals. Native species that successfully established and reproduced were functionally different in LNC than the resident community, while successful exotic species were functionally more similar to the resident community in LNC.Our study demonstrates that exotic species outperformed native species regardless of the presence of litter or herbivory pressure. Without the removal or thinning of litter, it is likely that exotic species will continue to dominate, resulting in positive feedback that further favours the persistence of exotic species within this invaded grassland system. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Functional traits constitute a promising research avenue to explain and predict ecological patterns at different levels of organization (genotypes, populations, communities) because they link individual responses to environmental conditions. However, Argentine ecologists and botanists seem not to have explored this line of research as much as colleagues in other parts of the world. With this work I intend to promote the use of functional traits among local and regional readers. Amalgamating often conflicting definitions proposed by other authors, I define functional traits as morphological characteristics that affect a chain of physiological and ecological processes that I refer to as function, vital rate, and population fitness. The purpose of this definition is to emphasize the mechanistic relationship between plant structure and function. The practical benefits are straightforward: predicting the future of a plant or a group of plants from their physical properties, which are generally easier to obtain than physiological or phenological measures. Next, I use two types of graphical tools to discuss the functionality of four key traits: potential plant height, seed mass, leaf mass per area, and leaf size. These graphical tools are (i) path diagrams that show direct or indirect, positive or negative connections between traits and fitness and (ii) cartesian graphs that describe the functional relationships between traits and vital rates that, when combined, result in optimum trait-fitness relationships. Theory indicates that such optimum relationships would be the norm rather than the exception, even though functional traits are generally interpreted as "indicators" of plant functions, which exclusively implies linear relationships. These graphical tools may help us produce predictions that guide data generation and contribute to fill important information gaps regarding the mechanistic link between plant form and population fitness. Although functional traits alone are unlikely to offer complete explanations or infallible predictions, ignoring them would deny us an irreplaceable source of information to understand and predict plant population and community responses to environmental conditions in a changing world. [ABSTRACT FROM AUTHOR]

Plant functional traits can greatly influence invasion success on islands. However, interrelationships between traits and invasion success are rarely integrated with the island biogeography theory. Here, we explored relations between functional traits and plant distributions to assess which traits are associated with invasion success (i.e. high island occupancy), test whether non-native richness and seed mass of species with distinct growth forms and dispersal modes vary differently with island characteristics (e.g. area, isolation, exposure to ocean-borne disturbances, distance from the nearest urban area, and whether islands were managed for conservation), and whether results differ from native species. We assembled a database of 264 northern New Zealand offshore islands, amalgamating species lists from field surveys and previously published data, and comprising 822 native and 855 non-native species. Non-native graminoids occurred on islands more frequently than forbs and woody species, and long-distance dispersal modes (wind, animal, unspecialized) more than species with short-distance dispersal modes. Most differences among trait categories of non-native species were associated with human-related variables (i.e. distance from the nearest urban area, and whether islands were conservation areas). Non-native plant species with high island occupancy were less commonly associated with human-related variables than non-native species with low island occupancy. Instead, they were more similar in their distributional patterns to native species within the same trait category, suggesting comparable processes regulate both sets of species. Our results illustrate that integrating trait-based approaches in the island biogeography framework can be a useful tool in understanding and predicting plant invasions. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms that shape the geographic distribution of plant species is a central theme of biogeography. Although seed mass, seed dispersal mode and phylogeny have long been suspected to affect species distribution, the link between the sources of variation of these attributes and their effects to the distribution of seed plants are poorly documented. This study aims to quantify the joint effects of key seed traits and phylogeny on species' distribution. We collected seed mass and seed dispersal mode from 1,426 species of seed plants representing 501 genera of 122 families and used 4,138,851 specimens to model species distributional range size. Phylogenetic generalized least squares regression and variation partitioning were performed to estimate the effects of seed mass, seed dispersal mode and phylogeny on species distribution. We found that species distributional range size was significantly constrained by phylogeny. Seed mass and its intraspecific variation were also important in limiting species distribution, but their effects were different among species with different dispersal modes. Variation partitioning revealed that seed mass, seed mass variability, seed dispersal mode and phylogeny together explained 46.82% of the variance in species range size. Although seed traits are not typically used to model the geographic distributions of seed plants, our study provides direct evidence showing seed mass, seed dispersal mode and phylogeny are important in explaining species geographic distribution. This finding underscores the necessity to include seed traits and the phylogenetic history of species in climate-based niche models for predicting the response of plant geographic distribution to climate change. [ABSTRACT FROM AUTHOR]

Seed production in Pinus pinaster Aiton is not usually considered a limiting factor for natural regeneration; instead, seed weight is a more limiting factor in successful pine recruitment. Divergent relationships between seed weight and germination rate were previously observed amongst maritime pine populations of central coastal Portugal. The present study followed cone-to-seed and seed-to-seedling approaches to decrease intra-specific variability and clarify the impact of cone size and seed mass on seedling recruitment. The main objectives of this study were (1) to determine and compare the mass of cones and seeds of three maritime pine populations located along a geographic gradient along the coastal center of Portugal and (2) to clarify the relations thereof between cone and seed traits with germination phenology and initial seedling growth. Results demonstrated that heavier cones tended to generate more mature seeds, but not necessarily heavier ones, although seed weight was suggested to be an indicator of robust seedlings. The outcomes of this study reinforce the great intra-population variability of maritime pine, showing the ecology of this species and its ability to adapt to various environments successfully. [ABSTRACT FROM AUTHOR]

Background and aimsAesculus L. (horse chestnut, buckeye) is a genus of 12-19 extant woody species native to the temperate Northern Hemisphere. This genus is known for unusually large seeds among angiosperms. While chromosome counts are available for many Aesculus species, only one has had its genome size measured. The aim of this study is to provide more genome size data and analyse the relationship between genome size and seed mass in this genus.MethodsChromosome numbers in root tip cuttings were confirmed for four species and reported for the first time for three additional species. Flow cytometric measurements of 2C nuclear DNA values were conducted on eight species, and mean seed mass values were estimated for the same taxa.Key resultsThe same chromosome number, 2 n = 40, was determined in all investigated taxa. Original measurements of 2C values for seven Aesculus species (eight taxa), added to just one reliable datum for A. hippocastanum , confirmed the notion that the genome size in this genus with relatively large seeds is surprisingly low, ranging from 0·955 pg 2C -1 in A. parviflora to 1·275 pg 2C -1 in A. glabra var. glabra.ConclusionsThe chromosome number of 2 n = 40 seems to be conclusively the universal 2 n number for non-hybrid species in this genus. Aesculus genome sizes are relatively small, not only within its own family, Sapindaceae, but also within woody angiosperms. The genome sizes seem to be distinct and non-overlapping among the four major Aesculus clades. These results provide an extra support for the most recent reconstruction of Aesculus phylogeny. The correlation between the 2C values and seed masses in examined Aesculus species is slightly negative and not significant. However, when the four major clades are treated separately, there is consistent positive association between larger genome size and larger seed mass within individual lineages.

The forage yield and quality of artificial grasslands typically decline rapidly over time after planting. Moreover, the reason for this decline of artificial grassland remains unclear. Here, we evaluated the relationship between years since planting and annual net primary productivity (ANPP), seed yield, and reproductive allocation (ie., the ratio of seed yield to annual net primary productivity) for eight common gramineous species separately planted in monoculture artificial grasslands in the Qinghai-Tibetan Plateau. We utilized T50 values (the time when ANPP or seed yield drop to 50% of their maximum values) to quantify the decline rates of eight artificial grasslands respectively, and additionally evaluated the influence of evolutionary history and other plant attributes on T50 (ANPP) and T50 (seed yield). We found that both ANPP and seed yield decreased linearly over time following planting for all species. ANPP generally declined more rapidly than did seed yield. The reproductive allocation of Deschampsia cespitosa, Festuca kirilowii, Festuca kryloviana, and Festuca sinensis increased significantly over time after planting. We did not observe any association of evolutionary history, seed mass, plant height, reproductive allocation, ANPP (second year), seed yield (second year) with T50 (ANPP) and T50 (seed yield). In addition, clonal propagation mode may influence declines of artificial grassland, and evolutionary history may shape shifts in reproductive allocation with plant population aging. This study was the first to utilize T50 values for the study of artificial grassland declines. Our research framework thus has the potential to guide future quantitative studies of artificial grassland declines.

In the context of climate change in recent years, the fate of woody plant seed has an important impact on forest regeneration. Seed mass is an important reproductive strategy of plants. There are huge differences between gymnosperms (mainly conifers) and angiosperms (flowering plants) in terms of reproduction and hydraulic strategies; however, little is known about changes in seed mass along climate aridity gradients between taxonomical groups such as gymnosperms and angiosperms, which limit our understanding on the fate of woody plants under warming-induced climate drying. We collected seed mass data from a total of 2575 woody plant individuals, including 145 species of gymnosperms and 1487 species of angiosperms, across different climatic zones in China. We mapped the distribution pattern of gymnosperm and angiosperm seed mass in China, with angiosperms being maximal near the 400 mm iso-precipitation line. Our phylogenetic analysis results show that seed mass exhibited significant phylogenic signals (p < 0.001) and was also strongly influenced by functional traits (growth type, fruit type, and dispersal mode). The results of linear regression and hierarchical partitioning analysis showed a stronger correlation between gymnosperm seed mass and environmental factors, and a higher independent aridity index effect on gymnosperm seed mass than angiosperm seed mass. The different patterns of seed mass along a climate aridity gradient between gymnosperms and angiosperms may point to different future fates for these two taxonomic groups, while the higher sensitivity of gymnosperm seed mass to environmental conditions may reduce their reproductive rate under the background of climate warming and drying.

Most terrestrial plants disperse by seeds, yet the relationship between seed mass, seed dispersal traits, and plant dispersion is poorly understood. We quantified seed traits for 48 species of native and introduced plants from the grasslands of western Montana, USA, to investigate the relationships between seed traits and plant dispersion patterns. Additionally, because the linkage between dispersal traits and dispersion patterns might be stronger for actively dispersing species, we compared these patterns between native and introduced plants. Finally, we evaluated the efficacy of trait databases versus locally collected data for examining these questions. We found that seed mass correlated positively with the presence of dispersal adaptations such as pappi and awns, but only for introduced plants, for which larger-seeded species were four times as likely to exhibit dispersal adaptations as smaller-seeded species. This finding suggests that introduced plants with larger seeds may require dispersal adaptations to overcome seed mass limitations and invasion barriers. Notably, larger-seeded exotics also tended to be more widely distributed than their smaller-seeded counterparts, again a pattern that was not apparent for native taxa. These results suggest that the effects of seed traits on plant distribution patterns for expanding populations may be obscured for long-established species by other ecological filters (e.g., competition). Finally, seed masses from databases differed from locally collected data for 77% of the study species. Yet, database seed masses correlated with local estimates and generated similar results. Nonetheless, average seed masses differed up to 500-fold between data sources, suggesting that local data provides more valid results for community-level questions.

A goal in trait‐based ecology is to understand and predict plant community responses to environmental change; however, diversity stored within seed banks that may expand or limit these responses is typically overlooked. If seed banks store attributes that are more advantageous or vulnerable under future conditions, they could impact community adaptability to change and disturbance. We explored compositional differences between seed banks and vegetation (i.e., seed bank bias) across a 12‐site gradient of increasingly higher and older soil terraces, asking: How do seed banks contribute to taxonomic and functional composition, and what do shifts in seed bank biases along the gradient (i.e., tracking) reveal about the processes driving seed bank variation and its implications for community adaptability? Across the gradient, seed banks stored distinct pools of species that added to species richness but not functional dispersion. Seed banks were generally biased toward short‐life histories and "fast" species with small seeds, thinner and more acquisitive roots, and lower root biomass allocation; however, trait means in the seed bank and vegetation sometimes shifted along the gradient, amplifying or reversing these biases. For example, species with higher specific leaf area (tied to rapid resource acquisition) tended to dominate vegetation on lower soil terraces, but were more common in the seed bank on higher terraces—at least when patterns were weighted by species' relative abundances. Although seed banks were generally characterized by "fast" attributes, observed shifts in seed bank biases across the gradient—particularly in leaf traits—demonstrate that environment can impact stored diversity and, consequently, our expectations for future vegetative turnover. The seed bank bias patterns that we characterized could be the result of many potential processes, including environment‐ or trait‐driven variation in seed bank inputs (seed production, dispersal) or losses (seed desiccation, germination), and may have important implications for a system's adaptive capacity. Only by integrating seed banks into the functional ecology agenda will we be able to unpack these processes and use seed banks more effectively in both prediction and ecosystem management. [ABSTRACT FROM AUTHOR]

Gynomonoecy, the occurrence of both pistillate (female) and perfect (hermaphroditic) flowers on the same plant, has received little attention compared to gynodioecy and other plant sexual systems. Eremurus anisopterus is a perennial ephemeral in the cold desert of northwest China with a hermaphrodite–gynomonoecious sexual system in the same population. The primary aim of this study was to compare the early life history traits and inbreeding depression between progeny from pistillate and hermaphrodite flowers in hermaphrodites and gynomonoecious individuals. All of the traits of progeny from outcrossed pistillate flowers on gynomonoecious plants were significantly greater than for other pollination types. Selfing (vs. outcrossing) resulted in a decrease in all traits, indicating inbreeding depression (ID) during early life history stages of gynomonoecious and hermaphroditic plants. ID for seed mass, seed germination and seedling survivorship under water stress for pistillate flowers on gynomonoecious plants was significantly higher than it was for hermaphrodite flowers on both gynomonoecious and hermaphrodite plants. The advantage of the offspring of pistillate (vs. hermaphrodite) flowers may contribute to the maintenance of gynomonoecy in E. anisopterus in its cold desert sand dune habitat. [ABSTRACT FROM AUTHOR]

Quantifying intraspecific trait variation (ITV) is crucial for understanding species local adaptation and regional distribution. Intraspecific seed mass variation (ITVsm) is expected to vary with environmental gradients or co-vary with related biotic attributes, but these relationships are not well known in a multispecies space. We performed interspecific and phylogenetic analyses to evaluate the relative power of three species biotic attributes and four niche breadth traits in explaining ITVsm variation for 434 eastern Qinghai–Tibetan species. We showed a positive relationship between species' ITVsm and their niche breadth in the light, moisture and disturbance dimensions, supporting the idea that high ITV allows species to match their traits to different habitat conditions and thus to distribute in a wide range of environments. However, we did find significant direct effect of species' thermal niche on individual seed mass variation. Meanwhile, we showed significant effects of seed dispersal mode, but not of life form and pollination type, on ITVsm. This suggests that the covariation or co-evolution between seed and disperser was related to the pattern and magnitude of ITVsm, but not to plant lifespan, the quality and allocation pattern of available resources and the availability of pollination vector. Lastly, all multivariate models showed a significant combined contribution of species' biotic attributes and niche breadth to their ITVsm, implying that intrinsic biotic limitations and extrinsic abiotic pressures may operate simultaneously in controlling regional-scale intraspecific seed development. [ABSTRACT FROM AUTHOR]

The evolution of persistent calyces may be an adaptation to ensure reproductive success of certain flowering plants. However, experimental evidence of the functions of persistent calyces during flowering and seed development remains scarce. We explored the possible functions of persistent calyces in Salvia miltiorrhiza , a perennial herb with campanulate calyx. We conducted calyx manipulation experiments to examine whether persistent calyces affect visitation rates of nectar robbers and pollinators, individual flower longevity, fruit set, seed set and seed mass. Our findings suggested that shortening of the calyx significantly decreased individual flower longevity, fruit set and seed mass, but did not affect visitation of pollinators and nectar robbers. In addition, the seed set of control flowers and the flowers with calyx shortened at the beginning of fruiting stage (CSF flowers) did not significantly differ, but both were higher than that of the flowers with calyx shortened at the beginning of blooming stage (CSB flowers). The seed set and fruit set of CSB flowers were limited by pollination due to the reduction in floral longevity. We conclude that persistent calyces of S. miltiorrhiza may represent adaptive strategies to maintain floral longevity and increase plant fitness. Persistent calyces may provide protection for the growth of flowers and contribute resources to the development of fruits and seeds. [ABSTRACT FROM AUTHOR]

Main conclusion: The divergences in propagule mass have been more consistently associated with divergences in seed development duration or fruit pedicel cross-sectional area than with divergences in any other biotic factors. Allometry and Corner’s rule became an important theme in evolutionary biology of plant trait structure and function. Being one of the most widely noticed plant traits, propagule (seed and fruit) mass variation mechanism across species is still controversial. Here we examined correlations between propagule mass and seed development duration as well as other traits, such as cross-sectional area of fruit pedicel, life form, fruit type and leaf area over four census years, to test an important life history strategy for propagule biomass allocation. We investigated 491 species, belonging to 91 families and 320 genera, representing 95% of native wild species in Beijing Botanical Garden. The scaling correlations between propagule mass and seed development duration and the other traits were determined using phylogenetic generalized linear models. Results show a significant positive relationship among propagule mass and seed development duration, leaf area and pedicel cross-sectional area for all species and for each life form (except vines) regardless of phylogeny. The variation in seed mass has been more consistently associated with variation in seed development duration than with divergences in any other variable, such as growth form, fruit type, pedicel cross-sectional area and leaf area, whereas variation in fruit weight was found to be more associated with variation in pedicel cross-sectional area than the other. Biotic factors, such as seed development duration, pedicel cross-sectional area, growth form and leaf area, mediate propagule size variation, of which seed development duration or pedicel cross-sectional area is the most important. The results further supported a hypothesis that large-seeded species evolved owing to high photosynthate availability and growth allometry in plant body. A mechanistic mathematical model involving seed development duration was provided to expound propagule mass variations across species. [ABSTRACT FROM AUTHOR]

Although seed quality and quantity, as well as reproductive performance are important life history stages of plants, little is known about the reproductive responses of trees to environmental changes such as increased anthropogenic deposition of nitrogen (N) and phosphorus (P). Dioecious plants are good models with which to test the environmental impact on female or male reproductive responses individually. We analysed effects of different long-term nutritional availability on the reproductive performance of two dioecious species (Taxus baccata L. and Juniperus communis L.) characterised by different life histories. By using pot experiments with vegetatively propagated plants grown in different fertilisation conditions, we observed an increase in plant growth and strobili production but a decrease in seed efficiency. Seeds produced by fertilised plants had greater seed mass. Fertiliser addition did not change C or N content nor the C/N ratio of T. baccata seeds, but increased N content and the N/P ratio; however, it did lower the C/N ratio in J. communis. Fertilisation did not change the metabolite profile in T. baccata but 18 metabolites were changed in J. communis. The study revealed new links between species life history, environmental changes, and reproduction. The findings imply that future environmental conditions may alter both seed productivity, and quality, as well as plant reproductive behaviour. [ABSTRACT FROM AUTHOR]

We evaluated whether seed mass, handling time, handling efficiency and profitability account for (a) preferences in controlled experiments and (b) field‐diet composition of four bird species of the Monte desert, Argentina. The question of whether birds maximise their energy intake rates while feeding on seeds is assessed. We used feeding experiments with six native seed species of 0.07–0.75 mg (i.e. the seed‐size range consumed in nature), which account for 0.59–0.84 of the field diet of the four birds. We measured seed‐handling times and used published information on bird preferences and diets, and on seed chemistry, for further calculations. Bird preferences were always positively related to seed mass and also to seed profitability in the two intermediate‐sized birds. Diet composition correlated positively with seed mass and negatively with seed profitability in three species, but some birds also showed a flexible behaviour eating the most attractive seeds according to their availability. This behaviour is not genuinely opportunistic because it only focuses on a restricted fraction of the total seed species present in the field. Contrary to expectations of species coexistence due to resource partitioning, small and large birds showed similar feeding efficiencies when eating the smaller and the larger seeds. The positive association between seed mass and profitability in several studies suggests that most birds can maximise their energy reward, on average and in the long‐term, by preferring the larger seeds. A combination of potential feeding optimisation with certain flexibility in the field may characterise the feeding ecology of desert seed‐eating birds. [ABSTRACT FROM AUTHOR]

Seeds show important variation as plant regenerative units among species, but their evolutionary co-variations with other plant characteristics are still poorly understood. Whilst a positive association of seed mass with genome size (GS) and life forms has already been documented, a broad-scale quantification of their evolutionary correlation and adaptive selection has never been conducted. Here, we tested for correlated evolution of seed mass and GS towards distinct selective regimes related to life form in angiosperms. In particular, we tested the hypothesis that the selection toward lighter seeds and smaller genomes is stronger for annual plants, ensuring high regenerative potential. Using multivariate evolutionary models over a dataset containing 3242 species, we showed an overall positive correlated evolution of seed mass and GS deviating from a pure drift process. Instead, evolutionary changes in seed and genome sizes were driven by adaptive selection towards optimal values differing among life forms. Specifically, the evolutionary optima towards which the seed and genome sizes evolve show a covariation toward small values in annuals, intermediate values in perennial herbs and a trade-off between seed mass and GS in woody plants. Moreover, the evolutionary correlation between seed mass and GS is strongest in annuals as an adaption to complete their life cycle in a short time window, when environmental conditions are favourable for regeneration and development to maturity. The asymmetry in the correlated evolution acting on seed and genome sizes due to life form could explain how life-history traits interplay with functional traits and how plants have evolved diverse successful life-history strategies. [ABSTRACT FROM AUTHOR]

Premise: Yeasts are often present in floral nectar and can influence plant fitness directly (independently of pollinators) or indirectly by influencing pollinator visitation and behavior. However, few studies have assessed the effect of nectar yeasts on plant reproductive success or compared effects across different plant species, limiting our understanding of the relative impact of direct vs. indirect effects. Methods: We inoculated the nectar of six plant species in the field with the cosmopolitan yeast Metschnikowia reukaufii to analyze the direct and indirect effects on female reproductive success over 2 years. The pollinator assemblage for each species was recorded during both flowering years. Results: Direct yeast effects on female fecundity were statistically nonsignificant for all plant species. There were significant indirect, pollinator‐mediated effects on fruit production and seed mass for the two species pollinated almost exclusively by bumblebees or hawkmoths, with the direction of the effects differing for the quantity‐ and quality‐related fitness components. There were no consistent effects of the yeast on maternal fecundity for any of the species with diverse pollinator assemblages. Conclusions: Effects of M. reukaufii on plant reproduction ranged from negative to neutral or positive depending on the plant species. The among‐species variation in the indirect effects of nectar yeasts on plant pollination could reflect variation in the pollinator community, the specific microbes colonizing the nectar, and the order of microbial infection (priority effects), determining potential species interactions. Elucidating the nature of these multitrophic plant–pollinator–microbe interactions is important to understand complex processes underlying plant pollination. [ABSTRACT FROM AUTHOR]

Premise: Maternal effects have been demonstrated to affect offspring performance in many organisms, and in plants, seeds are important mediators of these effects. Some woody plant species maintain long‐lasting canopy seed banks as an adaptation to wildfires. Importantly, these seeds stored in serotinous cones are produced by the mother plant under varying ontogenetic and physiological conditions. Methods: We sampled the canopy seed bank of a highly serotinous population of Pinus pinaster to test whether maternal age and growth and the environmental conditions during each crop year affected seed mass and ultimately germination and early survival. After determining retrospectively the year of each seed cohort, we followed germination and early survival in a semi‐natural common garden. Results: Seed mass was related to maternal age and growth at the time of seed production; i.e., slow‐growing, older mothers had smaller seeds, and fast‐growing, young mothers had larger seeds, which could be interpreted either as a proxy of senescence or as a maternal strategy. Seed mass had a positive effect on germination success, but aside from differences in seed mass, maternal age had a negative effect and diameter had a positive effect on germination timing and subsequent survival. Conclusions: The results highlight the importance of maternal conditions combined with seed mass in shaping seedling establishment. Our findings open new insights in the offspring performance deriving from long‐term canopy seed banks, which may have high relevance for plant adaptation. [ABSTRACT FROM AUTHOR]

Although plant clonality is an important reproductive strategy complementing seed reproduction, their interrelationship is seldom studied. We evaluated how plant clonality, together with plant economics spectrum and architectural constraints, affect the generative reproduction characteristics of co-existing grassland species. For this purpose, we collected data on seed number, seed mass and seed yield (seed mass x seed number) per shoot of 56 herbaceous species from temperate grasslands in the White Carpathian Mts. (SE Czech Republic). Clonality had a weaker effect on seed traits than leaf economics and plant architecture. Metamer size showed the strongest relationship to seed number per shoot, while leaf dry matter content and canopy height were the most important factors affecting average seed mass in the studied species. Seed yield was affected by both leaf nitrogen and metamer size but only for plants with long lived shoots (di- and polycyclic). The negative correlation between seed mass and seed number per shoot for our dataset was confirmed. Our study did not support the idea that clonality is the most important factor affecting seed production in grassland species and pointed out complex relationships of coordinated traits in coexisting species. [ABSTRACT FROM AUTHOR]

Predictions of how vegetation responds to spatial and temporal differences in climate rely on established links with plant functional traits and vegetation types that can be encoded into Dynamic Global Vegetation Models. Individual traits have been linked to climate at species level and at community level within regions. However, a recent global assessment of aggregated community level traits found unexpectedly weak links with macroclimate, bringing into question broadscale trait–climate associations and implicating local-scale environmental differences in the filtering of communities. To further evaluate patterns in light of these somewhat contradictory results, we quantified the power of macro-environmental variables to explain aggregated plant community traits, taking advantage of new trait data for leaf area, plant height and seed mass combined with a national survey that records cover-abundance using consistent methods for a large number of plots across Australia. In contrast to the global study, we found that abundance-weighted community mean and variance of leaf area and maximum height were correlated with macroclimate. Height and leaf area were highest in wet (especially warm, wet) environments, with actual evapotranspiration explaining 30% of variation in leaf area and 26% in maximum height. Seed mass was weakly related to environment, with no variable explaining more than 5% of variance. Considering all three traits together in a redundancy analysis, the complete set of environmental variables explained 43% of variation in site-mean traits and 29% of within-site trait variance. While significant trait variation remains unexplained, the trait–environment relationships reported here suggest climatically-driven filtering plays a strong role in assembling these vegetation communities. Regional assessments using standardised species abundances can therefore be used to predict aspects of vegetation function. Our quantification of plant community trait patterns along macroclimatic gradients at continental scale thereby contributes a much-needed functional basis for Australian vegetation. [ABSTRACT FROM AUTHOR]

We evaluated whether seed mass, handling time, handling efficiency and profitability account for (a) preferences in controlled experiments and (b) field‐diet composition of four bird species of the Monte desert, Argentina. The question of whether birds maximise their energy intake rates while feeding on seeds is assessed. We used feeding experiments with six native seed species of 0.07–0.75 mg (i.e. the seed‐size range consumed in nature), which account for 0.59–0.84 of the field diet of the four birds. We measured seed‐handling times and used published information on bird preferences and diets, and on seed chemistry, for further calculations. Bird preferences were always positively related to seed mass and also to seed profitability in the two intermediate‐sized birds. Diet composition correlated positively with seed mass and negatively with seed profitability in three species, but some birds also showed a flexible behaviour eating the most attractive seeds according to their availability. This behaviour is not genuinely opportunistic because it only focuses on a restricted fraction of the total seed species present in the field. Contrary to expectations of species coexistence due to resource partitioning, small and large birds showed similar feeding efficiencies when eating the smaller and the larger seeds. The positive association between seed mass and profitability in several studies suggests that most birds can maximise their energy reward, on average and in the long‐term, by preferring the larger seeds. A combination of potential feeding optimisation with certain flexibility in the field may characterise the feeding ecology of desert seed‐eating birds.

Understanding the mechanisms underlying ecosystem resilience - why some systems have an irreversible response to disturbances while others recover - is critical for conserving biodiversity and ecosystem function in the face of global change. Despite the widespread acceptance of a positive relationship between biodiversity and resilience, empirical evidence for this relationship remains fairly limited in scope and localized in scale. Assessing resilience at the large landscape and regional scales most relevant to land management and conservation practices has been limited by the ability to measure both diversity and resilience over large spatial scales. Here, we combined tools used in large-scale studies of biodiversity (remote sensing and trait databases) with theoretical advances developed from small-scale experiments to ask whether the functional diversity within a range of woodland and forest ecosystems influences the recovery of productivity after wildfires across the four-corner region of the United States. We additionally asked how environmental variation (topography, macroclimate) across this geographic region influences such resilience, either directly or indirectly via changes in functional diversity. Using path analysis, we found that functional diversity in regeneration traits (fire tolerance, fire resistance, resprout ability) was a stronger predictor of the recovery of productivity after wildfire than the functional diversity of seed mass or species richness. Moreover, slope, elevation, and aspect either directly or indirectly influenced the recovery of productivity, likely via their effect on microclimate, while macroclimate had no direct or indirect effects. Our study provides some of the first direct empirical evidence for functional diversity increasing resilience at large spatial scales. Our approach highlights the power of combining theory based on local-scale studies with tools used in studies at large spatial scales and trait databases to understand pressing environmental issues.

Despite the long history of the study of the biodiversity-ecosystem function relationship, uncertainty remains about the relationship of natural grassland ecosystems under stressful conditions. Recently, trait- and phylogenetic-based tests provide a powerful way to detect the relationship in different spaces but have seldom been applied to stressful zones on a large spatial scale. We selected Qinghai-Tibetan as the study area and collected a grassland community database involving 581 communities. We calculated biomass and species', functional, and phylogenetic diversity of each community and examined their relationships by using linear and non-linear regression models. Results showed an overall positive biodiversity-productivity relationship in species', functional and phylogenetic space. The relationship, however, was non-linear, in which biodiversity explained better the variation in community biomass when species diversity was more than a threshold, showing a weak effect of biodiversity on ecosystem function in low species diversity communities. We also found a filled triangle for the limit of the relationship between species and functional diversity, implying that functional diversity differs significantly among communities when their species diversity is low but finally converges to be a constant with increasing communities' species diversity. Our study suggests that multiple niche processes may structure the grassland communities, and their forces tend to balance in high-biodiversity communities. [ABSTRACT FROM AUTHOR]

Persistence and colonization by tree species in an environment following a fire depends on the effects on seed germination and seedling development. We used seeds of Kielmeyera coriacea and Qualea parviflora as a model to test the effects of high temperatures on germination and initial development of tree seedlings.We exposed the seeds to heat flow (70, 100, 130, 150 or 170 °C) for 2 or 5 min and compared the germination with that of unheated seeds (control). Seedlings were then harvested after 3, 7 or 15 days to evaluate aerial and root mass, root:shoot ratio, presence of cotyledon opening, true leaves, and secondary roots.We found no effect on germination for seeds exposed to temperatures ≥150 °C. However, germination was significantly reduced for seeds exposed to 100 °C for both 2 and 5 min. The mass of 15‐day‐old K. coriacea seedlings was smaller when seeds were heated at 70 °C for 5 min or at temperatures higher or equal to 100 °C. Qualea parviflora seedlings did not show any difference in mass, but there were marginal differences in the presence of roots and the opening of cotyledons. Kielmeyera coriacea seedlings allocated biomass faster than Q. parviflora.High temperatures affect both quantity and quality of germinable seeds, as well as biomass allocation during initial seedling development. These factors may explain the decrease in seedlings observed after fire, suggesting a bottleneck effect that influences population dynamics and species persistence in systems with frequent fires. [ABSTRACT FROM AUTHOR]

Ecological selection is a major driver of community assembly. Selection is classified as stabilizing when species with intermediate trait values gain the highest reproductive success, whereas selection is considered directional when fitness is highest for species with extreme trait values. Previous studies have investigated the effects of different selection types on trait distribution, but the effects of selection on species diversity have remained unclear. Here, we propose a framework for inferring the type and strength of selection by studying species diversity and trait distribution together against null expectations. We use a simulation model to confirm our prediction that directional selection should lead to lower species diversity than stabilizing selection despite a similar effect on trait community‐weighted variance. We apply the framework to a mesocosm system of annual plants to test whether differences in species diversity between two habitats that vary in productivity are related to differences in selection on seed mass. We show that, in both habitats, species diversity was lower than the null expectation, but that species diversity was lower in the more productive habitat. We attribute this difference to strong directional selection for large‐seeded species in the productive habitat as indicated by trait community‐weighted mean being higher and community‐weighted variance being lower than the null expectations. In the less productive habitat, we found that community‐weighted variance was higher than expected by chance, suggesting that seed mass could be a driver of niche partitioning under such conditions. Altogether, our results suggest that viewing species diversity and trait distribution as interrelated patterns driven by the same process, ecological selection, is helpful in understanding community assembly. [ABSTRACT FROM AUTHOR]

Masting characterizes large, intermittent and highly synchronous seeding events among individual plants and is found throughout the plant Tree of Life (ToL). Although masting can increase plant fitness, little is known about whether it results in evolutionary changes across entire clades, such as by promoting speciation or enhanced trait selection. Here, we tested if masting has macroevolutionary consequences by combining the largest existing dataset of population-level reproductive time series and time-calibrated phylogenetic tree of vascular plants. We found that the coefficient of variation (CVp) of reproductive output for 307 species covaried with evolutionary history, and more so within clades than expected by random. Speciation rates estimated at the species level were highest at intermediate values of CVp and regional-scale synchrony (Sr) in seed production, that is, there were unimodal correlations. There was no support for monotonic correlations between either CVp or Sr and rates of speciation or seed size evolution. These results were robust to different sampling decisions, and we found little bias in our dataset compared with the wider plant ToL. While masting is often adaptive and encompasses a rich diversity of reproductive behaviours, we suggest it may have few consequences beyond the species level. This article is part of the theme issue 'The ecology and evolution of synchronized seed production in plants'. [ABSTRACT FROM AUTHOR]

In mountain ecosystems, temperature and precipitation change along elevation and determine the lower and upper limits of tree species which form forests. Early life performance of tree species has been assessed along elevational gradients as a proxy for several environmental variables. Here, we attempt to answer the following question: How does elevation provenance influence seed mass, viability, and germination of Queñoa (Polylepis spp.)? We worked with four species from two contrasting environments from northwest Argentina. We gathered seeds along elevation gradients, seeds were weighed, tested for viability (Triphenyltetrazoliumchlorid; TTC) and germination percentage in a controlled environment. The analysis was performed using Generalized Linear Models (GLM). We found low germination percentages in all species, probably related to low seed viability. The two species from humid environments had lower seed mass and higher germination percentages than the two species from dry environments. The effect of elevational provenance negatively affected the germination of two species, while the other two species were not affected. We conclude that although the four species studied belong to the same genus, their early life characteristics differ between environments and along elevational gradients according to species. Trends regarding future temperatures suggest increases in germination for two of our study species and no effects on the other two species. [ABSTRACT FROM AUTHOR]

Among the limitations for the use of direct seeding in the ecological restoration of severely degraded areas in tropical grasslands, the association between dry periods and an inhospitable substrate stands out. This work evaluated whether covering seed with a soil layer and the addition of a thin topsoil layer to the degraded substrate interferes with native plant establishment in degraded areas. The effect of rainfall variations on direct seeding results was also measured. The establishment of seven native species was evaluated under four different conditions: 1) seeding on degraded substrate, 2) seeding covered by 1 cm degraded substrate layer, 3) seeding on 1cm topsoil layer, and 4) seeding covered by 1 cm topsoil layer. In general, species with smaller seeds showed higher establishment percentages in treatments in which seeds were deposited on the substrate. Legume species, which have larger seeds, achieved better establishment percentage when seeds were covered by the substrate. The addition of topsoil was beneficial for Bulbostylis fimbriata (Cyperaceae), while for the other species, the effect was null or harmful. Data also showed that rainfall amount and distribution affected the establishment rate. Direct seeding is an advantageous alternative for the ecological restoration of tropical grassland degraded by mining. Better knowledge on sowing management and behavior of native species can contribute to improving the efficiency of this technique. [ABSTRACT FROM AUTHOR]

In flowering plants, the evolution of self‐fertilization (selfing) from obligate outcrossing is regarded as one of the most prevalent evolutionary transitions. The evolution of selfing is often accompanied by various changes in genomic, physiological and morphological properties. In particular, a set of reproductive traits observed typically in selfing species is called the "selfing syndrome". A mathematical model based on the kinship theory of genetic imprinting predicted that seed mass should become smaller in selfing species compared with outcrossing congeners, as a consequence of the reduced conflict between maternally and paternally derived alleles in selfing plants. Here, we test this prediction by examining the association between mating system and seed mass across a wide range of taxa (642 species), considering potential confounding factors: phylogenetic relationships and growth form. We focused on three plant families—Solanaceae, Brassicaceae and Asteraceae—where information on mating systems is abundant, and the analysis was performed for each family separately. When phylogenetic relationships were controlled, we consistently observed that selfers (represented by self‐compatible species) tended to have a smaller seed mass compared with outcrossers (represented by self‐incompatible species) in these families. In summary, our analysis suggests that small seeds should also be considered a hallmark of the selfing syndrome, although we note that mating systems have relatively small effects on seed mass variation. [ABSTRACT FROM AUTHOR]

Summary: Early‐stage fitness variation has been seldom evaluated at broad scales in forest tree species, despite the long tradition of studying climate‐driven intraspecific genetic variation. In this study, we evaluated the role of climate in driving patterns of population differentiation at early‐life stages in Pinus sylvestris and explored the fitness and growth consequences of seed transfer within the species range.We monitored seedling emergence, survival and growth over a 2‐yr period in a multi‐site common garden experiment which included 18 European populations and spanned 25° in latitude and 1700 m in elevation.Climate–fitness functions showed that populations exhibited higher seedling survival and growth at temperatures similar to their home environment, which is consistent with local adaptation. Northern populations experienced lower survival and growth at warmer sites, contrary to previous studies on later life stages. Seed mass was higher in populations from warmer areas and was positively associated with survival and growth at more southern sites. Finally, we did not detect a survival–growth trade‐off; on the contrary, bigger seedlings exhibited higher survival probabilities under most climatic conditions.In conclusion, our results reveal that contrasting temperature regimes have played an important role in driving the divergent evolution of P. sylvestris populations at early‐life stages. [ABSTRACT FROM AUTHOR]

Species‐rich communities are composed of several locally rare and a few abundant species. A trait‐based approach can derive general explanations for such species abundance distribution. However, for tree species in forests, the intraspecific variation of traits associated with the ontogeny and understory/canopy conditions must be considered. Here, we quantified intraspecific variation of leaf traits across saplings and adults in trees and tested if leaf and/or regenerative traits mediate the species abundance distribution of saplings and adults, and if saplings abundance also determines the abundance of adults in tree communities of Araucaria forests in Southern Brazil. We found intraspecific variation for specific leaf area (SLA) and leaf dry matter content (LDMC), but not for leaf area (LA). Adults have higher LDMC and lower SLA than saplings, suggesting a shift in investment strategies. Species abundant in saplings were associated with larger LA, whereas abundant species in the adults had lower SLA and LA and a larger number of seeds per fruit. The abundance of saplings also contributed to explaining the abundance of species as adults. Saplings experience low light availability in the understory, larger leaves are essential to maximising light capture. On the other hand, adult trees face high irradiation, windy and frost exposure conditions; species with lower SLA reach higher abundance. Regenerative traits were only relevant for the model of adults. Species abundance distribution in forests is related to functional traits, but the relationship is distinct for saplings and adults as leaf traits vary according to the ontogenetic stage and/or the environmental conditions imposed to individuals. In addition, we suggest the assembly of trees in the upper forest stratum is not only mediated by abiotic and biotic filters that favour some leaf and regenerative attributes, but also by lasting effects of variables that filtered out individuals in former development stages. [ABSTRACT FROM AUTHOR]

Abstract Greater pollination intensity can enhance maternal plant fitness by increasing seed set and seed quality as a result of more intense pollen competition or enhanced genetic sampling. We tested experimentally these effects by varying the pollen load from a single pollen donor on stigmas of female flowers of Dalechampia scandens (Euphorbiaceae) and measuring the effects on seed number and seed mass. Seed set increased rapidly with pollen number at low to moderate pollen loads, and a maximum set of three seeds occurred with a mean pollen load of 19 pollen grains. We did not detect a trade‐off between the number of seeds and seed mass within a fruit. Seed mass increased with increasing pollen load, supporting the hypothesis of enhanced seed quality via increased pollen‐competition intensity or genetic sampling. These results suggest that maternal fitness increases with larger pollen loads, even when the fertilization success is already high. Our results further highlight the importance of high rates of pollen arrival onto stigmas, as mediated by reliable pollinators. Comparing the pollen‐to‐seed response curve obtained in this experiment with those observed in natural populations suggests that pollen limitation may be more severe in natural populations than predicted from greenhouse studies. These results also indicate that declines in pollinator abundance may decrease plant fitness through lowered seed quality before an effect on seed set is detected.

Background: The evolutionary success of flowering plants is associated with the vast diversity of their reproductive structures. Despite recent progress in understanding angiosperm-wide trends of floral structure and evolution, a synthetic view of the diversity in seed form and function across angiosperms is lacking., Scope: Here we present a roadmap to synthesise the diversity of seed forms in extant angiosperms, relying on the morphospace concept, i.e. a mathematical representation which relates multiple traits and describes the realised morphologies. We provide recommendations on how to broaden the range of measurable traits beyond mass, by using key morphological traits representative of the embryo, endosperm, and seed coat but also fruit attributes (e.g., dehiscence, fleshiness). These key traits were used to construct and analyse a morphospace to detect evolutionary trends and gain insight into how morphological traits relate to seed functions. Finally, we outline challenges and future research directions, combining the morphospace with macroevolutionary comparative methods to underline the drivers that gave rise to the diversity of observed seed forms., Conclusions: We conclude that this multidimensional approach has the potential, although still untapped, to improve our understanding of covariation among reproductive traits, and further elucidate angiosperm reproductive biology as a whole., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Recruitment of new individuals from seed is a critical component of plant community assembly and reassembly, especially in the context of ecosystem disturbance and recovery. While frameworks typically aim to predict how communities will be filtered on the basis of traits influencing established plant responses to the environment, assembly from seed is more complex: the responses of seeds (affected by dormancy and germination function) and establishing plants (affected by root and leaf function) can both influence outcomes within a single growing season. This creates a potential role for a more diverse set seed and seedling traits, and for environmental variability on shorter timescales (e.g. seasonal versus annual dynamics), than are typically considered. We followed thousands of individual seeds comprising eleven herbaceous grassland species through the first growing season, seeking to uncover critical environmental (precipitation amount and timing) and trait‐based filters on seedling emergence and survival in assembling communities. We saw the biggest recruitment limitation when seeds failed to emerge, driven independently by a dry spring and interspecific variation in seed mass (positive effect) and seed dormancy (negative effect). Seedling survival rates were higher than emergence, with weaker predictive roles for traits like seedling root mass allocation (positive effect) and seed mass (positive under spring drought), and lesser impacts of summer rainfall on soil moisture and survival. Interestingly, most trait relationships were not conditional on rainfall, suggesting water‐independent mechanisms of their respective advantages. Although recruitment is a complex process, our findings suggest that trait‐based assembly frameworks can be a useful way to anticipate outcomes, particularly if dynamic early‐stage conditions (e.g. spring rainfall) and attributes (e.g. seed dormancy) receive greater attention. Given the importance of recruitment for community turnover in the context of global change and land management efforts, this is an area ripe for continued expansion in trait‐based and applied ecology. [ABSTRACT FROM AUTHOR]

Premise: Plant performance and functional traits vary considerably within species, particularly in response to environmental variation. Plant responses may reflect life‐history trade‐offs, such as between resource acquisition and resource conservation. Larger seeds may buffer young plants from the negative effects of environmental variation, such as limitations in nutrients or water. However, whether seed size plays a similar role in how plants respond to variation in their biotic environment, including competition and soil microbial communities, remains poorly understood. Methods: We used a greenhouse experiment to test the interactive effects of intraspecific competition, the origin of the soil microbial community, and seed size on performance and functional traits in Quercus rubra L. seedlings. Results: Intraspecific variation in seedling traits weakly aligned with a resource acquisition–conservation trade‐off. Across the wide range of initial acorn mass, competition decreased seedling biomass by about 35%. Competition directly decreased the root mass ratio and indirectly increased specific leaf area and specific root length, via the negative effects on total biomass. In contrast, soil microbial communities had minor effects on seedlings, and we found no differences between plants receiving soil originating from a conspecific adult and plants receiving soil originating from a heterospecific adult. Conclusions: Competition is a more important driver of intraspecific variation in young Quercus rubra seedling performance and traits, both directly and by delaying ontogenetic development, than soil microbial communities. Seed size is an important predictor of seedling biomass, but a larger seed does not necessarily buffer seedlings from the effects of competition. [ABSTRACT FROM AUTHOR]

Domestication generally involves two sequential processes: initial identification of wild species with desirable characteristics ('progenitor filtering') and subsequent artificial and natural selection that, respectively, improve features preferred by humans and adapt species to cultivation/captivity ('domestication selection'). Consequently, domesticated species can differ from wild species and may share characteristics owing to convergent evolution ('domestication syndrome'). Baring evolutionary constraints, domestication selection may generate extreme phenotypes that transcend the 'boundaries of nature' evident for wild species. Despite evidence of domestication syndromes in some clades, broader contributions of progenitor filtering and domestication selection to characteristics of contemporary domesticated species have received limited attention.Using comparative analysis of 49 grain‐crop and 87 wild annual plant species from 15 families, we (1) addressed whether plants of crop and wild species differ for mean seed number, per‐seed mass and total seed‐mass investment; (2) assessed contributions of (a) progenitor filtering and (b) domestication selection to these differences; (3) evaluated whether crop characteristics exceed the boundaries of nature and (4) assessed whether seed‐production characteristics of grain crops constitute components of a generic domestication syndrome.On average, grain‐crop plants produce heavier seeds and greater total seed mass than wild species, but seed number per plant does not differ. Comparison of wild species between genera with or without crop species found no evidence of progenitor filtering. In contrast, crop species differed from congeneric wild species for the mass traits, but not for seed number. Greater seed investment by crops is consistent with artificial selection for enhanced seed yield (mass per harvested area), whereas heavier individual seeds suggest selection for improved nutritional quality and (or) adaptation to cultivation environments.Seed number–size characteristics of grain‐crop species lie within the bivariate variation among wild species and so do not exceed the boundaries of nature. Seed number and size varied similarly between species types and generally aligned with seed‐investment isoclines, suggesting an upper investment limit.Despite greater average investment in seed production and individual seeds by grain‐crop species, seed‐production characteristics did not vary less among crop species than among wild species, which is inconsistent with a common domestication syndrome. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Within-plant variation in seed size may merely reflect developmental instability, or it may be adaptive in facilitating diversifying bet-hedging, that is, production of phenotypically diverse offspring when future environments are unpredictable. To test the latter hypothesis, we analyzed patterns of variation in seed size in 11 populations of the perennial vine Dalechampia scandens grown in a common greenhouse environment. We tested whether population differences in the mean and variation of seed size covaried with environmental predictability at two different timescales. We also tested whether within-plant variation in seed size was correlated with independent measures of floral developmental instability and increased under stressful conditions. Populations differed genetically in the amount of seed-size variation occurring among plants, among infructescences within plants, and among seeds within infructescences. Within-individual variation was not detectably correlated with measures of developmental instability and did not increase under stress, but it increased weakly with short-term environmental unpredictability of precipitation at the source-population site. These results support the hypothesis that greater variation in seed size is adaptive when environmental predictability is low. [ABSTRACT FROM AUTHOR]

With globalisation facilitating the movement of plants and seeds beyond the native range, preventing potentially harmful introductions requires knowledge of what drives the successful establishment and spread of alien plants. Here, we examined global‐scale relationships between naturalisation success (incidence and extent) and invasiveness, soil seed bank properties (type and densities) and key species traits (seed mass, seed dormancy and life form) for 2350 species of angiosperms. Naturalisation and invasiveness were strongly associated with the ability to form persistent (vs. transient) seed banks but relatively weakly with seed bank densities and other traits. Our findings suggest that seed bank persistence is a trait that better captures the ability to become naturalised and invasive compared to seed traits more widely available in trait databases. Knowledge of seed persistence can contribute to our ability to predict global naturalisation and invasiveness and to identify potentially invasive flowering plants before they are introduced. [ABSTRACT FROM AUTHOR]