BACKGROUND AND AIMS:Kelp forests provide myriad ecosystem services to human society, many of which are being eroded by climate-driven extreme events, before they have been measured. Here, we assess how dive tourism in giant kelp forests (Macrocystis pyrifera) has been impacted by marine heatwaves over three decades in southeast Tasmania. METHODS:Dive trip logs and business records were compiled from 1991-2021 from the Tasman Peninsula, Tasmania. Dives sites were georeferenced and matched to the dominant habitat (e.g. cave, wreck, sponge garden, kelp forest) for each dive site. The distribution and frequency of all dives conducted in giant kelp forests were analysed to determine changes in the gross margin of kelp forest dives over time. Dive patterns were compared to marine heatwave metrics and patterns in kelp forest cover from remote sensing data. KEY RESULTS:Giant kelp forest diving steadily increased in Tasmania between 1991-2010, before repeated marine heatwaves in 2010 and 2016 caused abrupt loss of kelp and eventual collapse of kelp forests diving by 2017. The sharp decline in dives in 2011 resulted in a 255% decrease to the gross margin for the local operator. Poleward retreat of giant kelp forests between 2001-2017 resulted in a ∼44 km increase in travel and 15% reduction in gross margin per trip, before their eventual loss from the region. CONCLUSION:Our results provide one of the first quantitative assessments of kelp forest dive tourism and highlights the fragility of these ecosystems to climate disruption. This study adds to the growing body of literature demonstrating social and economic impacts of climate extremes on kelp forest ecosystems and highlights the fundamental importance of healthy, functional kelp forests to support ecosystem services.
BACKGROUND AND AIMS:Ecologists have long sought to link within-population dynamics to patterns of species occurrence and persistence across the range. Theoretical models suggest pathogens have important implications for plant populations and perhaps even limit plant distributions, though more empirical evidence is needed, especially in wild plant populations. METHODS:In the field, we characterized the infection dynamics of phytoplasma, a vectored and sterilizing bacterial pathogen, in wild populations of white trillium. We identified the highest molecular matches for the local bacterial strain and putative vectors. We then leveraged iNaturalist data to reveal patterns and potential drivers of phytoplasma occurrence across the range of white trillium. KEY RESULTS:Within populations, we found that phytoplasma symptoms were more likely in low host density plots, where insects occupied a higher proportion of trillium, indicative of an encounter-dilution effect. Leafhoppers in the genus Empoasca were positive for phytoplasma, suggesting they are a candidate vector of disease between trilliums at our field site. The closest match to our local phytoplasma was related to 'Candidatus Phytoplasma pruni', ribosomal group 16SrIII-F. Phytoplasma symptoms were widely distributed across trillium's range, even at range edges, and probability of symptoms was significantly increased by proximity to cropland. CONCLUSIONS:We studied the impacts of a sterilizing, vector-transmitted pathogen on host plant populations and patterns of infection across host range. Our results suggest sap-feeding insects do not occupy all hosts at high host densities, thereby reducing transmission and leading to higher likelihood of finding infection at low host densities, and a higher proportion of host plants infected at low host densities. At a range-wide scale, we found evidence that the pathogen was able to persist across both the core and edge of host ranges. Thus, negative-density dependent sterilizing pathogens may challenge host populations across the range.
BACKGROUND AND AIMS:After having contributed treatments of Gnetum for various regional floras in the neotropics, it was decided to produce a monograph of the genus for the new world. METHODS:Specimen data from herbarium species were collected and recorded. Type specimens and synonymy were determined for each species. KEY RESULTS:A new species endemic to Vaupés, Colombia is described and illustrated. It is compared to the other neotropical species of Gnetum. A key to the nine neotropical Gnetum species is given as well as descriptions of those species with relevant specimen citations, distributions, and images.
BACKGROUND AND AIMS:Apomixis, the formation of seeds without recombination, facilitates adaptation and persistence under environmental change. By preserving hybrid genotypes over long time periods, apomixis may conserve adaptive trait combinations from parental niche margins. We tested whether apomictic entities occupy intermediate, marginal, or transgressive niche space relative to their parents and whether differentiation is associated with ploidy. METHODS:We studied polyploid Sorbus subgenus Aria in the Franconian Jura (Germany), comprising two progenitors Sorbus aria and S. collina, seven triploid entities, and a pool of genetically heterogenous individuals (single genotypes). Genetic structure was assessed using MIG-seq. Overall niche differentiation between parental taxa and hybrids was evaluated using Sørensen similarity of two-dimensional hypervolumes derived from principal component analysis (PCA) axes. Niche shifts were further analyzed using hypervolumes based on the three strongest PCA variables. Across 762 occurrences, observations ranged from 11 to 453 individuals per entity. KEY RESULTS:Environmental niche space was transgressive in three, significantly allocated towards the margins of parental niche space in one, while remaining intermediate in the other entities. Niche transgression occurred towards milder temperatures and drier conditions. Genetic analyses confirmed morphologically defined entities, although one morphotype was polyphyletic. Tetraploid S. collina significantly occupied warmer and wetter environments compared to other cytotypes. Triploids differed from S. aria along microtopographic gradients represented by the second PCA axis. CONCLUSIONS:Apomictic Sorbus entities show diverse strategies in niche occupation and can occupy environmental niche space at and beyond the limits of their parental taxa. Apomicts may conserve evolutionary adaptations at the edges of parental niche space that may otherwise be lost from, or fail to emerge in, the parental gene pool. Over long timescales these trait combinations may re-enter the parental gene pool through introgression, thereby reintroducing adaptations critical for survival under changing conditions.
BACKGROUND AND AIMS:The Arctic flora is widely considered evolutionarily young, reflecting the emergence of unprecedentedly cold environments during the late Pliocene-early Pleistocene transition. Although many Arctic plants are thought to be derived from temperate alpine ancestors, the historical relationship between high-latitude occupancy and lineage divergence remains unclear. Specifically, it remains unclear whether Arctic lineages originated from ancestors that already occupied high-latitude regions before the Arctic environment formed or originated through colonization after the Arctic environment was established. To address this question, we test demographic models associated with the divergence of the Arctic subgenus Eu-Phyllodoce and its sister alpine subgenus (Parabryanthus) within Phyllodoce (Ericaceae). METHODS:Whole-genome data from Phyllodoce were used to infer phylogenetic relationships and demographic history. Demographic parameters were estimated in an isolation-with-migration model and evaluated using log-likelihood ratio tests. Historical demographic trajectories were additionally reconstructed using the pairwise sequentially Markovian coalescent (PSMC). KEY RESULTS:Demographic inference recovered a smaller ancestral effective population size for Eu-Phyllodoce than for Parabryanthus, indicating disproportional retention of ancestral polymorphism. PSMC further showed pronounced demographic expansion in Eu-Phyllodoce following divergence of ancestral lineages, consistent with a strong founder effect in the Arctic lineage. These results are consistent with the scenario that Eu-Phyllodoce originated through novel Arctic colonization. CONCLUSION:Our findings support the view that many Arctic plant lineages are evolutionarily young and highlight the roles of climatic cooling during the late Pliocene-early Pleistocene and of novel Arctic colonization in shaping the assembly of the extant Arctic flora.
BACKGROUND AND AIMS:Plant invasion poses severe threats to biodiversity, ecosystem stability, and human society. The prevailing "small-genome advantage" hypothesis-which attributes invasiveness to compact genomes that allow fast growth, high seed output, and short generation times-cannot explain why some aggressive invaders carry relatively large genomes. Here, we seek to explore why some large-genome plants are highly invasive. METHODS:Using the pantropical, large-genome invader Mikania micrantha as a model, we integrate controlled experiments, whole-genome resequencing, and transcriptomics to show that long-terminal-repeat retrotransposons (LTR-RTs)-the dominant repeats comprising 54.22% of its genome-may confer an advantage during rapid range expansion. KEY RESULTS:Populations with larger genomes tended to exhibit stronger drought responsive activation of specific Ty1-copia and Ty3-gypsy retrotransposons. These elements may contribute to phenylpropanoid pathway activation, which indicates a potentially adaptive role of phenylpropanoids in drought response. CONCLUSIONS:Genomic abundance is associated with environmental responsiveness, and LTR-RTs may function as eco-evolutionary catalysts that could allow large-genome plants to expand their ranges and become formidable invaders. Our findings uncover a previously overlooked benefit of large genomes and highlight transposon-driven plasticity as a candidate driver of invasion success worthy of further investigation.
BACKGROUND AND AIMS:The development of grains at different spikelet positions and floret positions in wheat is determined by the flow efficiency of the vascular bundle system in the spike. However, the developmental characteristic of vascular bundles in the wheat spike lacks systematic research, and the distribution and branching pattern remain unclear. METHODS:The developmental patterns of vascular bundles in the wheat rachis and rachilla were systematically studied using resin slicing and microscopic observation techniques. KEY RESULTS:The differentiation of vascular bundles in the rachis was earlier than that in the spikelet, and the vascular bundle network in the spike were completely formed before flowering. At the approach of the spikelet, the area of rachis vascular bundles on the spikelet side increased and new multiple vascular bundles were generated to flow into the spikelet. The vascular bundles entering the spikelet continued to branch, with a small portion flowing into the glume and the majority flowing into the first and second florets, respectively. Additionally, the rest vascular bundles flowed into the third floret, and the vascular bundles in the fourth and distal florets were derived from the branch of vascular bundles in the lower rachilla. The weight of grains in the middle and lower spikelet were significantly higher than those in the upper spikelet. The accumulation of main storage substances in the endosperm, including starch and protein, and grain weight at proximal G1 position in the middle spikelet was optimal compared to distal G3 position. CONCLUSIONS:Our observations suggest that the developmental pattern and spatial distribution of vascular bundles may contribute to positional differences in grain development within the wheat spike. The results provide the anatomical basis for understanding the vascular bundles development and grain synchronous development in the spike.
BACKGROUND AND AIMS:Global warming impacts on key plant life-history stages represent a central focus in ecology. Seed germination, the critical starting point in the plant life cycle, lacks a systematic understanding of its response mechanisms to climate warming. METHODS:Here, we examined how warming at the maternal, cold stratification, and germination stages affects seed germination in ten alpine plant species. KEY RESULTS:Cold stratification (absence vs. presence) is decisive in regulating seed dormancy, but its effect is modulated by temperatures experienced during both the maternal and germination stages. Importantly, "historical" warming during the maternal and cold stratification stages had a stronger influence on seed germination than "current" warming. We further found complex interactions among temperature signals across stages, in that thermal experience at one stage can alter how germination responds to temperature at other stages. These interactions also were species-specific. CONCLUSIONS:This study reveals integrated effects of multi-stage temperature memory in seed germination, highlighting the essential role of past environmental experiences in mediating plant responses to climate warming. Our findings offer a new theoretical basis for predicting future changes in plant population dynamics and community composition.
Abstract The Brassicaceae (Cruciferae) has long served as one of the pre-eminent model families for flowering plants, a status reinforced by the landmark sequencing of the Arabidopsis thaliana genome almost 30 years ago (Arabidopsis Genome Initiative, 2000). This special issue of Annals of Botany, entitled ‘Advances in Crucifer Research in the -Omics Era’, grew out of the vibrant discussions held during the 2024 International Botanical Congress in Madrid. It highlights a renaissance in crucifer research, in which traditional systematics and phylogenetics are being transformed by high-throughput omics approaches, providing large datasets and subjecting them to more rigorous analyses than was done previously. These advances now allow researchers to move beyond a single model species and view the entire family as a comparative genomic laboratory, opening opportunities for previously unthinkable comparative studies, bridging disciplines and reaffirming the Brassicaceae as one of the most important model families of flowering plants.
BACKGROUND AND AIMS:Tropical coastal marine ecosystems depend on macroalgal epiphyte-host networks, yet their architecture and vulnerability remain poorly characterised in the Caribbean. This study characterised the topological structure of Cuba's epiphyte-host network, identified determinants of epiphytic richness, and developed an integrated vulnerability index for conservation prioritisation. METHODS:A bipartite network was constructed from 130 host taxa and 266 epiphytic macroalgae. Network topology was analysed via degree distribution, community detection, and centrality. Host habitat distributions were inferred with a hierarchical Bayesian model. Epiphytic richness was modelled using Bayesian negative binomial regression with habitat breadth and betweenness centrality as predictors. Niche overlap was assessed with Jaccard similarity and Monte Carlo tests. Structural robustness was evaluated through sequential host removal, and an Integrated Vulnerability Index combined habitat environmental vulnerability with network irreplaceability. KEY RESULTS:The network exhibits scale-free architecture, where few hosts support most interactions. Betweenness centrality outperformed habitat breadth as a predictor of epiphytic richness. Epiphyte assemblages were highly distinct among hosts (mean similarity < 3%). Simulated loss showed network collapse after removing just 14.6% of central hosts, versus 64.6% under random loss. Rhizophora mangle, Thalassia testudinum, and Digenea simplex emerged as irreplaceable hubs whose loss would trigger secondary extinctions. CONCLUSIONS:The network is efficient yet fragile, depending disproportionately on few engineering hosts. The Integrated Vulnerability Index offers a transferable framework for conservation prioritisation. Prioritising these engineering hosts will safeguard cryptic biodiversity sustained by the interaction network.
BACKGROUND AND AIMS:The classic hypothesis that compound leaves are associated with drought has largely treated all woody plants as a single functional group, overlooking potential ecological divergence among shrubs, trees, and lianas. METHODS:Using 2,727 species across 63 forest plots in China, we quantified compound-leaf proportion within shrubs, trees, and lianas, respectively, and assessed their climatic associations, and employed PLS-SEM to disentangle direct and indirect pathways of drought influence. KEY RESULTS:Compound-leaf distribution differed markedly among life forms. The shrub compound-leaf proportion showed strong positive correlations with drought index and negative correlations with mean annual precipitation (MAP) and temperature (MAT). Trees exhibited a weak negative correlation with MAP and no significant relationship with MAT or drought index. while lianas displayed no climatic relationships-their proportion instead varying geographically. Structural equation modeling revealed that drought is associated with woody compound-leaf proportion primarily through indirect pathways: increasing shrub proportion (which carries high compound-leaf proportion) while reducing tree proportion, together with direct positive effects on compound-leaf proportion within shrubs and trees. CONCLUSIONS:Our findings demonstrate that compound leaf-drought relationships are life-form-specific, challenging the view of compound leaves as a universal drought-associated trait. Integrating life-form information into ecological models is essential for accurately predicting vegetation responses to climate change.
BACKGROUND AND AIMS:Water availability is the most limiting factor for global agricultural productivity. Rain-fed smallholder farming common to sub-Saharan Africa is particularly sensitive to unpredictable precipitation patterns and periods of drought - issues that are projected to be exacerbated by ongoing climate change. Common bean (Phaseolus vulgaris) is widely cultivated in East Africa and represents an important source of protein, carbohydrates, micronutrients and income for smallholder agriculture. Bean water-use traits and productivity responses to water limitation are thus of great importance. In this study we sought to investigate the genetic variation of water-use traits and responses to terminal drought among Rwandan landraces and improved cultivars of common bean. METHODS:Eighteen landraces and twelve improved cultivars were cultivated under realistic field conditions and evaluated for physiological traits related to water use, phenological properties, and effects of terminal drought treatment. KEY RESULTS:Considerable genetic variation was detected across landraces and improved cultivars for all investigated traits. There was a strong negative correlation between yield and intrinsic water-use efficiency. High yielding cultivars demonstrated low water-use efficiency. There was, however, also notable variation in this relationship, with some cultivars combining water-conserving properties and high productivity. Phenological data indicated a positive relationship between productivity and time to maturity. The lack of a consistent association between water-use traits and drought responses demonstrates that traits for drought avoidance and tolerance are genetically distinct and regulated separately. CONCLUSIONS:Our results demonstrate a large degree of genetic variation and highlight the possibility of combining traits for water economy and drought tolerance while maintaining yield in common bean. The contrasting genotypes reported in this study could be used for genetic mapping of genomic regions and cultivars combining high grain yield with moderate water use and moderate tolerance to drought are suggested for future breeding efforts.
BACKGROUND AND AIMS:Polyploidization is one of the major evolutionary forces in grasses (Poaceae), yet the genomic relationships between polyploid species across different continents remain poorly understood. Here, we aim to determine whether phylogenetically distinct South American allohexaploid fescues, Festuca ulochaeta Steud. (subg. Subulatae) and F. fimbriata Ness. (subg. Mallopetalon) retain a shared ancestral (pivotal) genome with the broad-leaved Eurasian fescues of subg. Schedonorus. METHODS:We used comparative cytogenetics (genomic in situ hybridization) coupled with flow cytometry. KEY RESULTS:Flow cytometry confirmed that both species are hexaploid (2n = 6x = 42) with genome sizes of 10.84 and 11.59 pg/2C, respectively. In situ hybridization demonstrated that F. ulochaeta and F. fimbriata are closely related to each other, and that the genome of F. ulochaeta is closely related to one of the diploid genomes of the tetraploid F. glaucescens, the tetraploid progenitor of hexaploid tall fescue (F. arundinacea). The F. ulochaeta DNA probe consistently labelled 14 chromosomes in tetraploids F. mairei, F. apennina, and F. glaucescens, in both (Continental and Mediterranean) morphotypes of hexaploid F. arundinacea and in octoploid F. atlantigena, indicating a shared pivotal diploid genome linking South American and Eurasian lineages. This trans-continental genomic affinity supports the role of South America as a secondary centre of Festuca diversification and implies that an ancestral diploid lineage colonized the continent prior to, or concurrent with, allopolyploidization. CONCLUSIONS:We revealed, for the first time, the genomic connection between polyploid South American and European fescues. This has direct implications for understanding the evolution of the haplo-insufficient meiotic pairing regulator present in polyploid fescues and for exploiting South American germplasm in grass breeding.
BACKGROUND:Blue carbon has become an important component of climate mitigation policy, integrating selected coastal ecosystems into greenhouse gas accounting frameworks. With their high productivity and large spatial extent, seaweed ecosystems have recently entered this debate, particularly in Europe where interest in seaweed-based climate strategies is expanding. However, it remains uncertain whether the evidence currently available for wild seaweed ecosystems meets the standards required for inclusion in formal blue carbon accounting. SCOPE:This review systematically assesses empirical evidence from European wild seaweed ecosystems. Sixteen empirical studies were evaluated using a structured classification framework based on three accounting-relevant pillars: permanence, defined as carbon storage exceeding 100 years; the feasibility of monitoring, reporting, and verification; and demonstrable net climate benefit after accounting for losses and variability. Review and policy literature were examined to contextualise these findings. CONCLUSIONS:No current wild seaweed ecosystem evidence consistently satisfied all three pillars for policy-grade accounting. Evidence for durable carbon storage was limited and highly context-specific. Monitoring approaches were generally site-based and not readily scalable to inventory-level reporting, while net climate benefit was frequently reduced or offset by greenhouse gas emissions and temporal variability. These findings highlight a mismatch between seaweed carbon dynamics, the current evidence base, and accounting requirements. The findings support a precautionary policy approach that prioritises conservation-led management of wild seaweed ecosystems. Current evidence does not yet support their inclusion in blue carbon accounting frameworks and indicates that future research should address permanence, monitoring, reporting and verification feasibility, and net climate benefit.
BACKGROUND AND AIMS:Clonal and non-clonal perennial herbs differ in adult architecture, particularly in the presence of belowground clonal organs. These contrasting strategies may already shape biomass allocation in young plants, potentially constraining growth and recovery from disturbance. We tested whether clonal and non-clonal perennial herbs differ in biomass allocation scaling during establishment and whether disturbance produces persistent changes in these scaling relationships after recovery. METHODS:We conducted a greenhouse experiment with 31 temperate meadow perennial herbs exposed to five disturbance treatments (two levels of aboveground biomass removal, belowground injury, flooding, and spring frost). Disturbed plants were harvested after approximately three months of recovery. We quantified biomass in major compartments and analysed scaling relationships among them. KEY RESULTS:Belowground-aboveground scaling was isometric at the age of two months, shifting weakly toward allometry at the age of five months, with no differences between strategies. After recovery, disturbance did not alter belowground-aboveground, leaf-stem, or generative-aboveground scaling. By contrast, a potential strategy signal emerged in turnover. Dead-aboveground biomass scaling was allometric, differed between clonal and non-clonal herbs, and disturbance reduced this allometry in non-clonals, while leaving it stable in clonals. CONCLUSIONS:During the first year of life, strategy differences were not evident in biomass allocation scaling among major living compartments, but a potential strategy signal emerged in aboveground turnover. These results suggest that establishment and season-end recovery in perennial herbs proceed within conserved scaling constraints, whereas strategy divergence may first be expressed through tissue turnover and become more apparent later as persistent clonal organs begin to form.
BACKGROUND AND AIMS:Laser Biospeckle Activity (LBSA), derived from laser-induced speckle variations in response to dynamic changes in living tissues, is a promising non-invasive technique for evaluating seed germination. METHODS:Malting barley (Hordeum vulgare subsp. distichum L. cv. Sinfonia) seeds were analysed using five coefficients-Generalised Differences (GD), Fujii, Lasca, Frequent Motion Image (FMI), and Moment of Inertia (MI)-to assess their ability to discriminate between treatments and tissue regions, and to track changes during imbibition. Whole and longitudinally cut seeds from two treatments (control [untreated] and autoclaved [heat-inactivated]) were analysed, focusing on embryo/endosperm activity ratios. LBSA was also evaluated as a function of imbibition time and seed moisture content. KEY RESULTS:Four coefficients (GD, Fujii, FMI, and MI) successfully differentiated control and autoclaved seeds, as well as embryo and endosperm regions in control seeds, revealing distinct activity patterns. In control seeds, LBSA increased with imbibition time and was well described by polynomial models (quadratic for Fujii and MI; cubic for GD and FMI). GD, Fujii, and FMI required a minimum seed moisture content of 25% to detect activity, while MI was responsive only above 31.5%. In contrast, Lasca was exclusively sensitive to hydration level, fitting a relaxation curve independent of treatment. CONCLUSIONS:LBSA constitutes a robust, non-destructive methodology for monitoring early germination processes. By combining coefficients, it is possible to infer physiological traits such as embryo specificity, hydration thresholds, and dynamic metabolic reactivation. This positions LBSA not only as a diagnostic tool for seed viability but also as a physiologically informative proxy for studying germination and tissue-level dynamics.
