Maoqin Xia, Joongku Lee, Limin Yu, Xianyun Mu, Wei-Mei Jiang, Douglas E. Soltis, Luxian Liu, Pan Li
Premise
The demographic histories of temperate plants in Northeast Asia in response to Quaternary climate oscillations have long been the focus of evolutionary biologists, but have rarely been studied in herbaceous plants. Here, we investigated the phylogeographic patterns of Mukdenia and Oresitrophe.
Methods
We sequenced two plastid regions for O. rupifraga (22 populations, 222 individuals), M. acanthifolia (five populations, 50 individuals), and M. rossii (14 populations, 139 individuals). To better understand the phylogeographic patterns of these species, we analyzed genetic diversity/structure, divergence times, demographic history, and distributional changes (with ecological niche modeling). We compared the inferred niche space of these species and addressed isolation by distance (IBD) and isolation by environment (IBE).
Results
We confirmed the monophyly of each species and detected a phylogeographic division corresponding to an arid belt in North China. Oresitrophe rupifraga is inferred to have contracted into four refugia during Pleistocene interglacial periods. Mukdenia acanthifolia and M. rossii appear to have retreated to the Changbai Mountains and Korean Peninsula during that time. In contrast, a larger potential geographic distribution was inferred for each species during glacial periods. Significant ecological niche differentiation was detected among the three species, which may have been associated with their genetic divergence.
Conclusions
Refugial isolation, climatic barriers, and niche differentiation likely influenced the genetic divergence of Oresitrophe and Mukdenia. Our study has implications for the structure of plant diversity in temperate deciduous forests of Northeast Asia and provides insights into conservation units worthy of protection and management for species of both genera.
{"title":"Refugial isolation and ecological niche differentiation promote genetic divergence of Oresitrophe and Mukdenia in Northeast Asia","authors":"Maoqin Xia, Joongku Lee, Limin Yu, Xianyun Mu, Wei-Mei Jiang, Douglas E. Soltis, Luxian Liu, Pan Li","doi":"10.1002/ajb2.70088","DOIUrl":"10.1002/ajb2.70088","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>The demographic histories of temperate plants in Northeast Asia in response to Quaternary climate oscillations have long been the focus of evolutionary biologists, but have rarely been studied in herbaceous plants. Here, we investigated the phylogeographic patterns of <i>Mukdenia</i> and <i>Oresitrophe</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We sequenced two plastid regions for <i>O. rupifraga</i> (22 populations, 222 individuals), <i>M. acanthifolia</i> (five populations, 50 individuals), and <i>M. rossii</i> (14 populations, 139 individuals). To better understand the phylogeographic patterns of these species, we analyzed genetic diversity/structure, divergence times, demographic history, and distributional changes (with ecological niche modeling). We compared the inferred niche space of these species and addressed isolation by distance (IBD) and isolation by environment (IBE).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We confirmed the monophyly of each species and detected a phylogeographic division corresponding to an arid belt in North China. <i>Oresitrophe rupifraga</i> is inferred to have contracted into four refugia during Pleistocene interglacial periods. <i>Mukdenia acanthifolia</i> and <i>M. rossii</i> appear to have retreated to the Changbai Mountains and Korean Peninsula during that time. In contrast, a larger potential geographic distribution was inferred for each species during glacial periods. Significant ecological niche differentiation was detected among the three species, which may have been associated with their genetic divergence.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Refugial isolation, climatic barriers, and niche differentiation likely influenced the genetic divergence of <i>Oresitrophe</i> and <i>Mukdenia</i>. Our study has implications for the structure of plant diversity in temperate deciduous forests of Northeast Asia and provides insights into conservation units worthy of protection and management for species of both genera.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144991125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hanna Makowski, Keric Lamb, Austin M. Kim, Emily Scott, Laura F. Galloway
Premise
Transitions from outcrossing to selfing often drive the evolution of floral traits in a predictable way. However, these expectations are not as straightforward for mixed-mating systems. In this study, we examine variation in pollen-collecting hairs, a floral structure involved in secondary pollen presentation within Campanulaceae. While secondary pollen presentation is hypothesized to have evolved to promote outcrossing, we evaluate the association of pollen-collecting hairs with selfing ability.
Methods
We characterized pollen-collecting hair morphology and retraction phenology in 15 populations of Campanula americana with known variation in self-fertilization ability using time-series collections and automated image analysis of pollen-collecting hair length.
Results
There was two-fold variation in the length of pollen-collecting hairs across populations that was associated with a population's within-flower selfing ability. Retraction rate of pollen-collecting hairs also varied among populations and was associated with selfing ability. Populations with greater selfing ability had longer hairs that retracted quickly early in floral anthesis.
Conclusions
We show pollen-collecting hairs, a trait thought to have evolved to promote outcrossing, is associated with within-flower selfing ability. Through developmental changes in length, pollen-collecting hairs appear to be a plastic phenotype that is both associated with autonomous selfing and with outcrossing in C. americana. This provides support for trait specialization rather than trade-offs, and for the ‘best of both worlds’ hypothesis of mixed mating-system evolution.
{"title":"Trait specialization facilitates autonomous selfing ability in a mixed-mating plant","authors":"Hanna Makowski, Keric Lamb, Austin M. Kim, Emily Scott, Laura F. Galloway","doi":"10.1002/ajb2.70095","DOIUrl":"10.1002/ajb2.70095","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Transitions from outcrossing to selfing often drive the evolution of floral traits in a predictable way. However, these expectations are not as straightforward for mixed-mating systems. In this study, we examine variation in pollen-collecting hairs, a floral structure involved in secondary pollen presentation within Campanulaceae. While secondary pollen presentation is hypothesized to have evolved to promote outcrossing, we evaluate the association of pollen-collecting hairs with selfing ability.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We characterized pollen-collecting hair morphology and retraction phenology in 15 populations of <i>Campanula americana</i> with known variation in self-fertilization ability using time-series collections and automated image analysis of pollen-collecting hair length.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>There was two-fold variation in the length of pollen-collecting hairs across populations that was associated with a population's within-flower selfing ability. Retraction rate of pollen-collecting hairs also varied among populations and was associated with selfing ability. Populations with greater selfing ability had longer hairs that retracted quickly early in floral anthesis.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>We show pollen-collecting hairs, a trait thought to have evolved to promote outcrossing, is associated with within-flower selfing ability. Through developmental changes in length, pollen-collecting hairs appear to be a plastic phenotype that is both associated with autonomous selfing and with outcrossing in <i>C. americana</i>. This provides support for trait specialization rather than trade-offs, and for the ‘best of both worlds’ hypothesis of mixed mating-system evolution.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 9","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70095","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144999480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flower color polymorphism (FCP) is thought to be driven by multiple selection agents. Although widely associated with visual attraction of multiple pollinators, FCP is also often correlated with abiotic factors. We explored the links between abiotic conditions, flowering phenology, and FCP in the winter-flowering geophyte Anemone coronaria L., which forms color-polymorphic or red-only populations.
Methods
We mapped the geographical distribution of color diversity in A. coronaria in Israel using citizen-science data. We recorded the phenology and density of red and non-red flowers during two flowering seasons in 18 plots along a rainfall gradient. We related the spatiotemporal data to soil and climate measures.
Results
Color-polymorphic populations are restricted to Mediterranean sites (>450 mm annual rainfall, >60% soil saturation), whereas red populations are found in Mediterranean and in semiarid sites, and in soils with high (>15%) soil calcium carbonate (CaCO3) content. Greater soil electrical conductance (salts and water) was predictive of earlier first flowers. Flowering started earlier in Mediterranean than in semiarid plots, and earlier in non-red than in red flowers. Temperature and soil potassium concentrations (for non-red flowers) or sand content (for red flowers) were predictive of the timing of peak flowering.
Conclusions
The spatiotemporal patterns of FCP in A. coronaria may reflect adaptation of red flowers to stressful semiarid abiotic conditions and to pollinator preferences. Abiotic conditions that delay flowering may benefit red anemones by enhancing their probability of encountering glaphyrid beetles, their specialized pollinators.
{"title":"Color polymorphism in Anemone coronaria: Correlations with soil, climate, and flowering phenology","authors":"Tzlil Labin, Banisha Phukela, Tamar Keasar, Nirit Lavie-Alon, Yuval Sapir","doi":"10.1002/ajb2.70093","DOIUrl":"10.1002/ajb2.70093","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Flower color polymorphism (FCP) is thought to be driven by multiple selection agents. Although widely associated with visual attraction of multiple pollinators, FCP is also often correlated with abiotic factors. We explored the links between abiotic conditions, flowering phenology, and FCP in the winter-flowering geophyte <i>Anemone coronaria</i> L., which forms color-polymorphic or red-only populations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We mapped the geographical distribution of color diversity in <i>A. coronaria</i> in Israel using citizen-science data. We recorded the phenology and density of red and non-red flowers during two flowering seasons in 18 plots along a rainfall gradient. We related the spatiotemporal data to soil and climate measures.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Color-polymorphic populations are restricted to Mediterranean sites (>450 mm annual rainfall, >60% soil saturation), whereas red populations are found in Mediterranean and in semiarid sites, and in soils with high (>15%) soil calcium carbonate (CaCO<sub>3</sub>) content. Greater soil electrical conductance (salts and water) was predictive of earlier first flowers. Flowering started earlier in Mediterranean than in semiarid plots, and earlier in non-red than in red flowers. Temperature and soil potassium concentrations (for non-red flowers) or sand content (for red flowers) were predictive of the timing of peak flowering.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The spatiotemporal patterns of FCP in <i>A. coronaria</i> may reflect adaptation of red flowers to stressful semiarid abiotic conditions and to pollinator preferences. Abiotic conditions that delay flowering may benefit red anemones by enhancing their probability of encountering glaphyrid beetles, their specialized pollinators.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"113 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70093","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144991120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kimberley J. Simpson, Claire M. Belcher, Sarah J. Baker
Premise
Humans have used fire to manage landscapes for millennia, but this use of fire is declining in many ecosystems. Understanding how plants respond to these changes is key to predicting ecosystem resilience and impacts on services such as biodiversity and carbon sequestration. However, many ecosystems lack data on plant fire responses. A solution is to infer these responses through studying functional traits that offer fitness benefits under fire by enabling species to resist fire, or persist through fire, by resprouting or recruitment from stored seed banks or dispersed seed. Studying these traits helps predict species performance under fire.
Methods
We used a trait-based approach to create a database of fire-relevant traits and fire responses for vascular and nonvascular plant species in UK heath and mire ecosystems managed by fire. By reviewing the available literature, we collected data on traits adaptive under frequent burns for 153 plant taxa that could then be used to make predictions about fire effects.
Results
Of the 153 taxa assessed, 97% had fire-adaptive traits; 149 taxa had resistance and/or persistence traits, enabling survival or regeneration after fire. Additionally, 20 taxa showed fire-enhanced recruitment, while only four lacked traits aiding survival during or after fire.
Conclusions
The database created here is designed to be a resource for those who study and manage heath and mire ecosystems. The use of fire in areas where heath is underlain by peat is much debated, and this database can inform how changing or removing the use of fire will impact plant communities.
{"title":"Adaptive plant traits under anthropogenic burning regimes: A database for UK heath and mire plant species","authors":"Kimberley J. Simpson, Claire M. Belcher, Sarah J. Baker","doi":"10.1002/ajb2.70090","DOIUrl":"10.1002/ajb2.70090","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Humans have used fire to manage landscapes for millennia, but this use of fire is declining in many ecosystems. Understanding how plants respond to these changes is key to predicting ecosystem resilience and impacts on services such as biodiversity and carbon sequestration. However, many ecosystems lack data on plant fire responses. A solution is to infer these responses through studying functional traits that offer fitness benefits under fire by enabling species to resist fire, or persist through fire, by resprouting or recruitment from stored seed banks or dispersed seed. Studying these traits helps predict species performance under fire.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We used a trait-based approach to create a database of fire-relevant traits and fire responses for vascular and nonvascular plant species in UK heath and mire ecosystems managed by fire. By reviewing the available literature, we collected data on traits adaptive under frequent burns for 153 plant taxa that could then be used to make predictions about fire effects.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Of the 153 taxa assessed, 97% had fire-adaptive traits; 149 taxa had resistance and/or persistence traits, enabling survival or regeneration after fire. Additionally, 20 taxa showed fire-enhanced recruitment, while only four lacked traits aiding survival during or after fire.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The database created here is designed to be a resource for those who study and manage heath and mire ecosystems. The use of fire in areas where heath is underlain by peat is much debated, and this database can inform how changing or removing the use of fire will impact plant communities.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70090","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144939388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Niger Sultana, Cate Macinnis-Ng, Sarah J. Richardson, Md Azharul Alam, Xinglei Cui, Sarah V. Wyse, Daniel C. Laughlin, Katherine Seward, George L. W. Perry, Timothy J. Curran
Premise
Relationships between flammability and drought tolerance influence vegetation dynamics during fires. A goal of the emerging subdiscipline of pyro-ecophysiology is to identify ecophysiological traits that determine live fuel flammability, but empirical studies of these relationships are rare. Furthermore, drought tolerance has been suggested as a surrogate for low flammability when choosing species to plant near houses in fire-prone areas, but this hypothesis has not been tested.
Methods
We examined links between flammability and drought tolerance for 39 woody species, compiling existing data on shoot flammability and six drought-related variables: minimum leaf water potential (Ψmin; N = 15 species), leaf turgor loss point (πtlp; N = 20), root zone water deficits (N = 19), days to plant death (N = 14), xylem embolism resistance (P50; N = 20), and wood density (WD; N = 20).
Results
Drought-tolerant species did not have low shoot flammability, except for a negative relationship between ignition percentage and WD, and then only for conifers. In contrast, there were significant negative relationships between four of five shoot flammability variables and either or both Ψmin and πtlp, showing that the most drought-tolerant species were also the most flammable. Ψmin and πtlp were positively associated with leaf water status, producing higher correlations with shoot flammability than other drought-response indicators.
Conclusions
Pyro-ecophysiological traits, e.g. Ψmin and πtlp, are useful predictors of interspecific variation in live fuel flammability, showing how pyro-ecophysiology can provide insights into how plants might respond to a more drought- and fire-prone future.
前提：可燃性和耐旱性之间的关系影响火灾期间植被的动态。热生态生理学这一新兴分支学科的一个目标是确定决定燃料可燃性的生态生理特征，但对这些关系的实证研究很少。此外，在选择在火灾易发地区的房屋附近种植的树种时，耐旱性被认为是低可燃性的替代品，但这一假设尚未得到验证。方法：对39种木本植物的可燃性与耐旱性之间的关系进行了研究，收集了现有的6个与干旱相关的变量：最小叶片水势（Ψmin; N = 15种）、叶片膨松损失点（πtlp; N = 20）、根区水分缺水量（N = 19）、植株死亡时间（N = 14）、木质部栓塞抗性（P50; N = 20）和木材密度（WD; N = 20）。结果：耐旱树种的枝梢可燃性不低，但与WD呈负相关，其次为针叶树；相反，5个可燃性变量中有4个与Ψmin和π - tlp或两者均呈显著负相关，说明最耐旱的树种也是最易燃的树种。Ψmin和π - tlp与叶片水分状态呈正相关，与茎部可燃性的相关性高于其他干旱响应指标。结论：高温生态生理特征，如Ψmin和π - tlp，是生物燃料可燃性种间变化的有效预测因子，表明高温生态生理可以为植物如何应对更干旱和火灾的未来提供见解。
{"title":"Testing key tenets of pyro-ecophysiology: Indicators of drought response in relation to shoot flammability","authors":"Niger Sultana, Cate Macinnis-Ng, Sarah J. Richardson, Md Azharul Alam, Xinglei Cui, Sarah V. Wyse, Daniel C. Laughlin, Katherine Seward, George L. W. Perry, Timothy J. Curran","doi":"10.1002/ajb2.70091","DOIUrl":"10.1002/ajb2.70091","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Relationships between flammability and drought tolerance influence vegetation dynamics during fires. A goal of the emerging subdiscipline of pyro-ecophysiology is to identify ecophysiological traits that determine live fuel flammability, but empirical studies of these relationships are rare. Furthermore, drought tolerance has been suggested as a surrogate for low flammability when choosing species to plant near houses in fire-prone areas, but this hypothesis has not been tested.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We examined links between flammability and drought tolerance for 39 woody species, compiling existing data on shoot flammability and six drought-related variables: minimum leaf water potential (<i>Ψ</i><sub>min</sub>; <i>N</i> = 15 species), leaf turgor loss point (<i>π</i><sub>tlp</sub>; <i>N</i> = 20), root zone water deficits (<i>N</i> = 19), days to plant death (<i>N</i> = 14), xylem embolism resistance (P<sub>50</sub>; <i>N</i> = 20), and wood density (WD; <i>N</i> = 20).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Drought-tolerant species did not have low shoot flammability, except for a negative relationship between ignition percentage and WD, and then only for conifers. In contrast, there were significant negative relationships between four of five shoot flammability variables and either or both <i>Ψ</i><sub>min</sub> and <i>π</i><sub>tlp</sub>, showing that the most drought-tolerant species were also the most flammable. <i>Ψ</i><sub>min</sub> and <i>π</i><sub>tlp</sub> were positively associated with leaf water status, producing higher correlations with shoot flammability than other drought-response indicators.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Pyro-ecophysiological traits, e.g. <i>Ψ</i><sub>min</sub> and <i>π</i><sub>tlp</sub>, are useful predictors of interspecific variation in live fuel flammability, showing how pyro-ecophysiology can provide insights into how plants might respond to a more drought- and fire-prone future.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 10","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70091","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144939382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniele Buono, Gudrun Kadereit, Aaron Liston, Shahin Zarre, Diego F. Morales-Briones
Premise
With over 3100 species, Astragalus L. (Fabaceae) has long fascinated botanists as the largest genus of flowering plants. With an origin in the Middle Miocene, Astragalus has one of the highest diversification rates known in flowering plants. Comprehensive taxonomic treatments exist, and the genus is currently subdivided into 136 sections in the eastern hemisphere and 93 sections in the western hemisphere based on morphological characters. Despite considerable efforts, a comprehensive and well-resolved phylogeny of the genus is still lacking.
Methods
Here, we reconstruct the backbone phylogeny of Astragalus using a custom bait set capturing 819 loci specifically designed for a target enrichment approach in the Astragalean clade. We carefully selected a set of 107 taxa representing all major clades currently recognized in Astragalus. Of those, 80 newly sequenced taxa were obtained from herbarium specimens as old as 110 years.
Results
We retrieved all the targeted loci and additional off-target plastome sequences for all samples, including the 80 herbarium specimens. Our phylogenetic analysis reinforced the currently accepted backbone phylogeny of Astragalus with high support and novel details, additionally providing insights into cytonuclear phylogenetic conflicts in the genus. Evidence for potential reticulate evolution was found, providing a possible explanation for the conflicts observed.
Conclusions
This work represents an important milestone in obtaining a comprehensive, herbarium-based phylogeny of Astragalus, which will constitute the base to study a wealth of relevant biological questions, for example, the still unanswered question of what drove the rapid diversification of Astragalus, with important repercussions on our understanding of diversification in natural contexts.
{"title":"Building a robust backbone for Astragalus using a clade-specific target enrichment bait set","authors":"Daniele Buono, Gudrun Kadereit, Aaron Liston, Shahin Zarre, Diego F. Morales-Briones","doi":"10.1002/ajb2.70084","DOIUrl":"10.1002/ajb2.70084","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>With over 3100 species, <i>Astragalus</i> L. (Fabaceae) has long fascinated botanists as the largest genus of flowering plants. With an origin in the Middle Miocene, <i>Astragalus</i> has one of the highest diversification rates known in flowering plants. Comprehensive taxonomic treatments exist, and the genus is currently subdivided into 136 sections in the eastern hemisphere and 93 sections in the western hemisphere based on morphological characters. Despite considerable efforts, a comprehensive and well-resolved phylogeny of the genus is still lacking.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Here, we reconstruct the backbone phylogeny of <i>Astragalus</i> using a custom bait set capturing 819 loci specifically designed for a target enrichment approach in the Astragalean clade. We carefully selected a set of 107 taxa representing all major clades currently recognized in <i>Astragalus</i>. Of those, 80 newly sequenced taxa were obtained from herbarium specimens as old as 110 years.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We retrieved all the targeted loci and additional off-target plastome sequences for all samples, including the 80 herbarium specimens. Our phylogenetic analysis reinforced the currently accepted backbone phylogeny of <i>Astragalus</i> with high support and novel details, additionally providing insights into cytonuclear phylogenetic conflicts in the genus. Evidence for potential reticulate evolution was found, providing a possible explanation for the conflicts observed.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This work represents an important milestone in obtaining a comprehensive, herbarium-based phylogeny of <i>Astragalus</i>, which will constitute the base to study a wealth of relevant biological questions, for example, the still unanswered question of what drove the rapid diversification of <i>Astragalus</i>, with important repercussions on our understanding of diversification in natural contexts.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 8","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70084","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144870835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nicholas J. Kooyers, Mark A. Genung, Simon G. Innes, Andrea Turcu, Donna M. Hinrichs, Benjamin J. LeBlanc, Courtney M. Patterson
Premise
The increasing frequency and severity of heat waves across the globe is well known. However, few longitudinal studies have tracked demographic change and fitness within natural populations, and fewer still have spanned multiple extreme events. Determining how organisms tolerate, respond, and potentially adapt to extreme events is key for assessing long-term population viability.
Methods
We examined how mortality, fecundity, seed provisioning, and offspring germination differed across 12 populations of annual common monkeyflower (Mimulus guttatus) over 5 years.
Results
Two heat waves occurred within the study: a heat wave within the first 10 days of the growing season in 2019 and a heat dome event nearly a month into the growing season in 2021. Mortality was high, and fecundity decreased in a population-specific manner following each heat wave. However, the 2021 heat dome caused declines of 34.5% in seed size and 22.1% in the ability to germinate, while the 2019 heat wave did not significantly affect either. Structural equation models indicated that similar climatic factors—including early-season maximum temperatures and late-season precipitation—are associated with declines in fecundity and slower germination.
Conclusions
These results suggest that the consequences of heat waves will depend on the relative severity and timing of the heat wave in the growing season, and further suggest that this timing may have amplified longer-term impacts because offspring have less provisioning. Specifically, with growing seasons shifting earlier into the spring, later or slower germination could exacerbate population extirpation risk.
{"title":"Heat waves decrease fitness and alter maternal provisioning in natural populations of Mimulus guttatus","authors":"Nicholas J. Kooyers, Mark A. Genung, Simon G. Innes, Andrea Turcu, Donna M. Hinrichs, Benjamin J. LeBlanc, Courtney M. Patterson","doi":"10.1002/ajb2.70087","DOIUrl":"10.1002/ajb2.70087","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>The increasing frequency and severity of heat waves across the globe is well known. However, few longitudinal studies have tracked demographic change and fitness within natural populations, and fewer still have spanned multiple extreme events. Determining how organisms tolerate, respond, and potentially adapt to extreme events is key for assessing long-term population viability.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We examined how mortality, fecundity, seed provisioning, and offspring germination differed across 12 populations of annual common monkeyflower (<i>Mimulus guttatus</i>) over 5 years.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Two heat waves occurred within the study: a heat wave within the first 10 days of the growing season in 2019 and a heat dome event nearly a month into the growing season in 2021. Mortality was high, and fecundity decreased in a population-specific manner following each heat wave. However, the 2021 heat dome caused declines of 34.5% in seed size and 22.1% in the ability to germinate, while the 2019 heat wave did not significantly affect either. Structural equation models indicated that similar climatic factors—including early-season maximum temperatures and late-season precipitation—are associated with declines in fecundity and slower germination.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>These results suggest that the consequences of heat waves will depend on the relative severity and timing of the heat wave in the growing season, and further suggest that this timing may have amplified longer-term impacts because offspring have less provisioning. Specifically, with growing seasons shifting earlier into the spring, later or slower germination could exacerbate population extirpation risk.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 8","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70087","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144870836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ian S. Pearse, Zoe Becker, Paul J. Ode, John F. Gaskin, Natalie M. West
Premise
Clonality, a form of asexual reproduction and spread, is common among invasive plants, though sexual reproduction via seeds is often still important for their long-range dispersal. In small populations, clonality has been hypothesized to interfere with sexual reproduction by limiting outcrossing opportunities of a plant.
Methods
We developed a structural equation model based on estimates of genetic diversity and seed production of Lepidium draba, a problematic invasive clonal plant, at 26 sites in Colorado to test whether site characteristics relating to small founder populations resulted in low genetic diversity and sexual reproduction. The next year, in pollen supplementation experiments at six sites (three with high genetic diversity, three with low), we tested whether populations with low genetic diversity were limited by non-self pollen.
Results
Large populations and populations associated with rivers tended to have higher genetic diversity. Percentage seed fill and total seed production were considerably higher at sites with higher genetic diversity. At populations with low genetic diversity, supplementation with pollen from outside of the site, but not from within the site, increased seed production. At populations with high genetic diversity, pollen supplementation from off-site did not increase seed production.
Conclusions
Our study shows that, in low-diversity populations that are dominated by a few large clones, L. draba produces few seeds compared to high-diversity populations and that this appears to be due to limited availability of non-self pollen. The data indicate that low genetic diversity decreases sexual reproduction, which may greatly reduce long-distance dispersal from these populations.
{"title":"Low genetic diversity in populations of a clonal invasive plant limits sexual reproduction","authors":"Ian S. Pearse, Zoe Becker, Paul J. Ode, John F. Gaskin, Natalie M. West","doi":"10.1002/ajb2.70083","DOIUrl":"10.1002/ajb2.70083","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Clonality, a form of asexual reproduction and spread, is common among invasive plants, though sexual reproduction via seeds is often still important for their long-range dispersal. In small populations, clonality has been hypothesized to interfere with sexual reproduction by limiting outcrossing opportunities of a plant.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We developed a structural equation model based on estimates of genetic diversity and seed production of <i>Lepidium draba</i>, a problematic invasive clonal plant, at 26 sites in Colorado to test whether site characteristics relating to small founder populations resulted in low genetic diversity and sexual reproduction. The next year, in pollen supplementation experiments at six sites (three with high genetic diversity, three with low), we tested whether populations with low genetic diversity were limited by non-self pollen.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Large populations and populations associated with rivers tended to have higher genetic diversity. Percentage seed fill and total seed production were considerably higher at sites with higher genetic diversity. At populations with low genetic diversity, supplementation with pollen from outside of the site, but not from within the site, increased seed production. At populations with high genetic diversity, pollen supplementation from off-site did not increase seed production.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our study shows that, in low-diversity populations that are dominated by a few large clones, <i>L. draba</i> produces few seeds compared to high-diversity populations and that this appears to be due to limited availability of non-self pollen. The data indicate that low genetic diversity decreases sexual reproduction, which may greatly reduce long-distance dispersal from these populations.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 8","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144844032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Large-scale disturbances significantly impact forest dynamics, structure, and biodiversity. Lianas proliferate rapidly after such events, likely through clonal reproduction. Understanding this process is challenging because it requires precise disturbance history and accurate estimation of whether individuals originated from clonal reproduction, seed reproduction, or preexisting vegetation.
Methods
We examined whether clonal reproduction drives liana proliferation in both early successional and mature forest conditions by analyzing the dominant liana species (Trachelospermum asiaticum var. asiaticum; Apocynaceae) in temperate forests on a volcanic island. The study included young forests recovering from a volcanic eruption 22 yr ago and old-growth forests unaffected by eruptions for >800 yr. We established six 100 m2 quadrats (three in each forest type), sampled 586 individuals, and used 11 microsatellite markers to assess genetic structure.
Results
Significant clonal expansion was observed in both forest types, but stem density and genetic diversity varied markedly. Old-growth forests had 14 times greater stem density and five times more genets (clones) than young forests, and exhibited unexpectedly greater clonal diversity despite their advanced successional stage. This indicates that clonal reproduction results in high abundance in both forest conditions, while both seed and clonal reproduction enhance clonal diversity in old-growth forests.
Conclusions
Our analysis revealed that a few genets, recruited via seed dispersal in early successional stages, rapidly expanded through extensive clonal reproduction, leading to long-term liana proliferation. These findings highlight how clonality and seed recruitment, together with environmental changes during succession, shape the population dynamics and clonal diversity of lianas following disturbances.
前提：大尺度扰动显著影响森林动态、结构和生物多样性。藤本植物在这些事件之后迅速繁殖，可能是通过无性繁殖。理解这一过程是具有挑战性的，因为它需要精确的干扰历史和准确的估计个体是来自无性繁殖、种子繁殖还是先前存在的植被。方法：通过分析优势藤本植物(Trachelospermum asiaticum var. asiaticum；夹竹桃科)生长于火山岛上的温带森林中。这项研究包括从22年前的火山爆发中恢复过来的年轻森林和800年前未受火山爆发影响的原始森林。我们建立了6个100 m2样方（每个森林类型3个），取样586个个体，使用11个微卫星标记对遗传结构进行评估。结果：两种林型克隆扩增均显著，但茎密度和遗传多样性差异显著。原生林的茎密度是幼林的14倍，基因（无性系）是幼林的5倍，尽管其演替阶段较晚，但却表现出出乎意料的更高的无性系多样性。这表明，在两种森林条件下，无性系繁殖都导致高丰度，而种子繁殖和无性系繁殖都增加了原生林的无性系多样性。结论：我们的分析表明，在演替早期通过种子传播获得的一些基因，通过广泛的无性系繁殖迅速扩展，导致藤本植物的长期增殖。这些发现强调了在演替过程中，无性系和种子招募以及环境变化如何影响干扰后藤本植物的种群动态和无性系多样性。
{"title":"Clonal reproduction as a driver of liana proliferation following large-scale disturbances in temperate forests","authors":"Hideki Mori, Takashi Kamijo","doi":"10.1002/ajb2.70085","DOIUrl":"10.1002/ajb2.70085","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Large-scale disturbances significantly impact forest dynamics, structure, and biodiversity. Lianas proliferate rapidly after such events, likely through clonal reproduction. Understanding this process is challenging because it requires precise disturbance history and accurate estimation of whether individuals originated from clonal reproduction, seed reproduction, or preexisting vegetation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We examined whether clonal reproduction drives liana proliferation in both early successional and mature forest conditions by analyzing the dominant liana species (<i>Trachelospermum asiaticum</i> var. <i>asiaticum</i>; Apocynaceae) in temperate forests on a volcanic island. The study included young forests recovering from a volcanic eruption 22 yr ago and old-growth forests unaffected by eruptions for >800 yr. We established six 100 m<sup>2</sup> quadrats (three in each forest type), sampled 586 individuals, and used 11 microsatellite markers to assess genetic structure.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Significant clonal expansion was observed in both forest types, but stem density and genetic diversity varied markedly. Old-growth forests had 14 times greater stem density and five times more genets (clones) than young forests, and exhibited unexpectedly greater clonal diversity despite their advanced successional stage. This indicates that clonal reproduction results in high abundance in both forest conditions, while both seed and clonal reproduction enhance clonal diversity in old-growth forests.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our analysis revealed that a few genets, recruited via seed dispersal in early successional stages, rapidly expanded through extensive clonal reproduction, leading to long-term liana proliferation. These findings highlight how clonality and seed recruitment, together with environmental changes during succession, shape the population dynamics and clonal diversity of lianas following disturbances.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 8","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70085","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144833748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p>Small, evergreen, and omnipresent, the bryophytes—comprising the liverworts, hornworts, and mosses—receive little attention, even with more than 19,000 species distributed across the globe (Brinda and Atwood, <span>2024</span>). They colonize almost any habitat and can find a place to settle between and on rocks, on other plants, on soil, on walls, on cars, and elsewhere. Having no vascular system and lacking roots makes them the ideal colonizers on any substrate. But they are small. They do not flower. They are difficult to identify. And yet they fulfill crucial ecosystem functions (Eldridge et al., <span>2023</span>), are used frequently in biotechnology (e.g., Horn et al., <span>2021</span>), and serve as models in physiological and genetic studies (e.g., Beaulieu et al., <span>2025</span>). They are not “lower plants” that have led to the evolution of “higher plants.” Rather, both vascular plants and bryophytes are derived from a complex ancestral land plant (Harris et al., <span>2022</span>). Recent viewpoints have synthesized the important roles that bryophytes play across ecosystems, calling for renewed attention to and inclusion of bryophytes in empirical and theoretical research (Deilmann et al., <span>2024</span>; Rousk and Villarreal, <span>2025</span>). One key feature of bryophytes is their ubiquitous associations with microorganisms, including N<sub>2</sub>-fixing prokaryotes (diazotrophs) that can supply ecosystems with readily available nitrogen (N). This association was first described in 1909—in half a sentence—by plant ecologist Eugene Warming in lecture notes at the University of Copenhagen. The field has progressed tremendously since then, and many of the abiotic controls of this key ecosystem function (i.e., N<sub>2</sub> fixation) have been identified in the past decade. It is now time to look ahead.</p><p>All plants associate with microorganisms, and one key role that microorganisms play is the fixation of atmospheric N<sub>2</sub>, converting inert N<sub>2</sub> into plant-available N. One enigmatic group that performs this ecosystem function is the Cyanobacteria, whose members often associate with vascular and non-vascular plants. Although liverwort-cyanobacteria and hornwort-cyanobacteria associations have been studied intensively, moss-cyanobacteria interactions remain comparatively understudied—even though all mosses are colonized by N<sub>2</sub>-fixing cyanobacteria. However, the degree of colonization varies widely among moss species, leading to large differences in N<sub>2</sub> fixation rates. Nevertheless, in unpolluted ecosystems, such as arctic tundra and boreal or tropical cloud forests, moss-cyanobacteria associations can contribute half of total ecosystem N input (Permin et al., <span>2022</span>). Nitrogen availability and humidity are the key drivers of cyanobacterial N<sub>2</sub> fixation associated with mosses, independent of habitat (Alvarenga and Rousk, <span>2022</span>). These abiotic controls h
作为一个整体，(1)苔藓很容易取样、运输和储存；（二）在环境条件不同的生境中发现的；(3)它们在数量、身份和位置方面与蓝藻的共生关系存在很大差异；(4)共生是可塑的（即它们可以随着环境条件的变化而变化）。因此，这些关联可以帮助我们回答诸如植物和重氮营养体参与什么类型的相互作用以及共生关系如何起源等问题。除了作为研究共生相互作用进化的模型系统外，这些关联也可以用来测试生命策略的进化理论。苔藓-蓝藻的关联是普遍超越北极，北方和热带栖息地。在温带草原（Calabria et al., 2020）和地中海橡树林等森林生态系统中发现了它们。在地中海生境中，苔藓相关重氮营养体的固氮作用比热带云雾森林高10倍，比温带森林高3个数量级（图2A）。温带地区的低N2固定率可能是由于大气沉降的相对高的背景N输入抑制了N2固定活性（Wang et al., 2022），地中海生态系统也可能是这种情况。尽管如此，地中海森林中与苔藓相关的氮固定高于其他被调查的生态系统，特别是在降雨事件之后。这暗示除氮沉降外还有其他控制因素。地中海苔藓在一年中的大部分时间里都是干燥的，因此其固氮活性可以忽略不计。然而，在降雨事件之后，苔藓的N2固定率可以迅速复苏（图2B）。这在其他生态系统中并不适用，这可能是生物适应干旱和短活动窗口的不同生命策略的结果。r/K选择理论是在20世纪70年代提出的（MacArthur和Wilson， 1967），其中r选择策略（快速而短暂的生命，通常在不稳定的环境中）与K选择策略（物种的承载能力，通常在稳定的环境中发现）形成对比。这个概念起源于生殖策略科学，已被应用于其他领域，包括保护生物学和植物传播，因为它是关于在不同环境中最大限度地适应。也许在零星降雨的地中海栖息地中，苔藓定植的蓝藻是r选择的策略，而在气候稳定的热带生态系统中，蓝藻是k选择的策略。这些动态使苔藓-蓝藻共生成为一个强大的、可访问的系统，用于将宏观生态学和进化概念应用于与植物宿主相关的微生物群落。苔藓-蓝藻关联代表了一个有前途的和未充分利用的模型系统，用于探索共生相互作用和微生物生活史策略的进化。苔藓物种和相关蓝藻在定植模式和对变化环境条件的响应方面的差异暗示了苔藓群体内不同的进化轨迹。此外，苔藓叶可以作为研究微生物与微生物相互作用和微观尺度上固定N2命运的运动场，因为蓝藻被大量其他微生物包围，这些微生物可能在苔藓宿主接触到固定N2之前就吸收了固定N2。通过整合生理学、生态学和进化的观点，苔藓-蓝藻系统的研究可以加深我们对植物-微生物相互作用的认识，并为我们对陆地生命共同进化的理解提供更广泛的见解。因此，这些系统在理论框架和实证研究中都值得更多的关注。
{"title":"Moss-cyanobacteria associations: A model for studying symbiotic interactions and evolutionary strategies","authors":"Kathrin Rousk","doi":"10.1002/ajb2.70086","DOIUrl":"10.1002/ajb2.70086","url":null,"abstract":"<p>Small, evergreen, and omnipresent, the bryophytes—comprising the liverworts, hornworts, and mosses—receive little attention, even with more than 19,000 species distributed across the globe (Brinda and Atwood, <span>2024</span>). They colonize almost any habitat and can find a place to settle between and on rocks, on other plants, on soil, on walls, on cars, and elsewhere. Having no vascular system and lacking roots makes them the ideal colonizers on any substrate. But they are small. They do not flower. They are difficult to identify. And yet they fulfill crucial ecosystem functions (Eldridge et al., <span>2023</span>), are used frequently in biotechnology (e.g., Horn et al., <span>2021</span>), and serve as models in physiological and genetic studies (e.g., Beaulieu et al., <span>2025</span>). They are not “lower plants” that have led to the evolution of “higher plants.” Rather, both vascular plants and bryophytes are derived from a complex ancestral land plant (Harris et al., <span>2022</span>). Recent viewpoints have synthesized the important roles that bryophytes play across ecosystems, calling for renewed attention to and inclusion of bryophytes in empirical and theoretical research (Deilmann et al., <span>2024</span>; Rousk and Villarreal, <span>2025</span>). One key feature of bryophytes is their ubiquitous associations with microorganisms, including N<sub>2</sub>-fixing prokaryotes (diazotrophs) that can supply ecosystems with readily available nitrogen (N). This association was first described in 1909—in half a sentence—by plant ecologist Eugene Warming in lecture notes at the University of Copenhagen. The field has progressed tremendously since then, and many of the abiotic controls of this key ecosystem function (i.e., N<sub>2</sub> fixation) have been identified in the past decade. It is now time to look ahead.</p><p>All plants associate with microorganisms, and one key role that microorganisms play is the fixation of atmospheric N<sub>2</sub>, converting inert N<sub>2</sub> into plant-available N. One enigmatic group that performs this ecosystem function is the Cyanobacteria, whose members often associate with vascular and non-vascular plants. Although liverwort-cyanobacteria and hornwort-cyanobacteria associations have been studied intensively, moss-cyanobacteria interactions remain comparatively understudied—even though all mosses are colonized by N<sub>2</sub>-fixing cyanobacteria. However, the degree of colonization varies widely among moss species, leading to large differences in N<sub>2</sub> fixation rates. Nevertheless, in unpolluted ecosystems, such as arctic tundra and boreal or tropical cloud forests, moss-cyanobacteria associations can contribute half of total ecosystem N input (Permin et al., <span>2022</span>). Nitrogen availability and humidity are the key drivers of cyanobacterial N<sub>2</sub> fixation associated with mosses, independent of habitat (Alvarenga and Rousk, <span>2022</span>). These abiotic controls h","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"112 8","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://bsapubs.onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.70086","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144820373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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