American Journal of Botany最新文献

{"title":"The landscape genetics of a mass-flowering fire-ephemeral plant","authors":"Mira Jordan,&nbsp;Jason Bragg,&nbsp;Mark Ooi,&nbsp;Marlien van der Merwe,&nbsp;Maurizio Rossetto,&nbsp;Will Cornwell","doi":"10.1002/ajb2.16432","DOIUrl":"10.1002/ajb2.16432","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Obligate fire ephemerals are annual plants that have germination and reproduction cued by fire occurrence, persisting between fire events in a long-lived soil seed bank. Within these species, gene flow is restricted not only geographically but also temporally because individuals are limited to reproducing with others affected by the same fire event. The patchwork-like distribution of fires may therefore promote population isolation. In contrast to past fires, the Australian fires of 2019–2020 were of unprecedented extent, providing an opportunity to investigate the landscape genetics of a fire ephemeral, <i>Actinotus forsythii</i>, across multiple populations and to compare it to a common congener, <i>Actinotus helianthi</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>For both species, we used single nucleotide polymorphisms to infer patterns of population structure and calculate measures of genetic diversity. We also estimated a phylogeny of <i>Actinotus forsythii</i> to understand the differentiation of a geographically isolated population.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>For <i>A. forsythii</i>, the within-population diversity (allelic richness = 1.56) was greater, and the among-population differentiation (<i>F</i>_ST = 0.30) was lower than that observed for <i>A. helianthi</i> (allelic richness = 1.33, <i>F</i>_ST = 0.57). <i>Actinotus forsythii</i> had distinct geographic groupings, and a geographically isolated population of this species was genetically highly differentiated.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Despite the fire-dependent, asynchronous gene flow, predicted between site disconnect, and possible within-site homogeneity, our results suggest that burn mosaic could be influencing gene flow patterns and fire-triggered mass flowering may promote genetic diversity within <i>Actinotus forsythii</i>.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 11","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142543138","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}

{"title":"Where did they come from, where did they go? Niche conservatism in woody and herbaceous plants and implications for plant-based paleoclimatic reconstructions","authors":"Zack J. Quirk,&nbsp;Selena Y. Smith,&nbsp;R. Paul Acosta,&nbsp;Christopher J. Poulsen","doi":"10.1002/ajb2.16426","DOIUrl":"10.1002/ajb2.16426","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>The ecological conditions that constrain plants to an environmental niche are assumed to be constant through time. While the fossil record has been used previously to test for niche conservatism of woody flowering plants, additional studies are needed in other plant groups especially since they can provide insight with paleoclimatic reconstructions, high biodiversity in modern terrestrial ecosystems, and significant contributions to agriculture.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We tested climatic niche conservatism across time by characterizing the climatic niches of living herbaceous ginger plants (Zingiberaceae) and woody dawn redwood (<i>Metasequoia</i>) against paleoniches reconstructed based on fossil distribution data and paleoclimatic models.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Despite few fossil Zingiberaceae occurrences in the latitudinal tropics, unlike living Zingiberaceae, extinct Zingiberaceae likely experienced paratropical conditions in the higher latitudes, especially in the Cretaceous and Paleogene. The living and fossil distributions of <i>Metasequoia</i> largely remain in the upper latitudes of the northern hemisphere. The Zingiberaceae shifted from an initial subtropical climatic paleoniche in the Cretaceous, toward a temperate regime in the late Cenozoic; <i>Metasequoia</i> occupied a more consistent climatic niche over the same time intervals.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Because of the inconsistent climatic niches of Zingiberaceae over geologic time, we are less confident of using them for taxonomic-based paleoclimatic reconstruction methods like nearest living relative, which assume a consistent climatic niche between extant and extinct relatives; we argue that the consistent climatic niche of <i>Metasequoia</i> is more appropriate for these reconstructions. Niche conservatism cannot be assumed between extant and extinct plants and should be tested further in groups used for paleoclimatic reconstructions.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 11","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11584045/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142493021","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}

{"title":"Continental sampling reveals core bacterial and environmentally driven fungal leaf endophytes in Heuchera","authors":"Dexcem J. Pantinople,&nbsp;Reagan Conner,&nbsp;Stephanie Sutton-Dauber,&nbsp;Kelli Broussard,&nbsp;Carolina M. Siniscalchi,&nbsp;Nicholas J. Engle-Wrye,&nbsp;Heather R. Jordan,&nbsp;Ryan A. Folk","doi":"10.1002/ajb2.16428","DOIUrl":"10.1002/ajb2.16428","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Endophytic plant-microbe interactions range from mutualistic relationships that confer important ecological and agricultural traits to neutral or quasi-parasitic relationships. In contrast to root-associated endophytes, the role of environmental and host-related factors in the acquisition of leaf endophyte communities at broad spatial and phylogenetic scales remains sparsely studied. We assessed endofoliar diversity to test the hypothesis that membership in these microbial communities is driven primarily by abiotic environment and host phylogeny.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We used a broad geographic coverage of North America in the genus <i>Heuchera</i> L. (Saxifragaceae), representing 32 species and varieties across 161 populations. Bacterial and fungal communities were characterized using 16S and ITS amplicon sequencing, respectively, and standard diversity metrics were calculated. We assembled environmental predictors for microbial diversity at collection sites, including latitude, elevation, temperature, precipitation, and soil parameters.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Assembly patterns differed between bacterial and fungal endophytes. Host phylogeny was significantly associated with bacteria, while geographic distance was the best predictor of fungal community composition. Species richness and phylogenetic diversity were consistent across sites and species, with only fungi showing a response to aridity and precipitation for some metrics. Unlike what has been observed with root-associated microbial communities, in this system microbes show no relationship with pH or other soil factors.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Overall, this work improves our understanding of the large-scale patterns of diversity and community composition in leaf endophytes and highlights the relative significance of environmental and host-related factors in driving different microbial communities within the leaf microbiome.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 11","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142493020","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}

{"title":"Drought mediates Sphagnum defense response to herbivory","authors":"Yong-Da Chen,&nbsp;Zhao-Jun Bu,&nbsp;Meng Wang,&nbsp;Ming-Ming Zhang,&nbsp;Jin-Ze Ma,&nbsp;Hong-Bo Guo","doi":"10.1002/ajb2.16427","DOIUrl":"10.1002/ajb2.16427","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>The expected concomitant increase in multiple stressors such as herbivory and drought may threaten peatland ecosystems. How <i>Sphagnum</i>, the ecological engineers of peatlands, responds to combined stressors remains largely unexplored. Here we aimed to clarify resource allocations in <i>Sphagnum</i> during concomitant herbivory and drought.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p><i>S. magellanicum</i> and <i>S. fuscum</i> were exposed to drought and herbivory together or separately in laboratory experiments and analyzed for growth (biomass production and net photosynthetic rate), defense (phenolics in leachates and phenolics in extraction) and nonstructural carbohydrates (soluble sugar and starch) in relation to untreated controls.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Herbivory and drought had significant interactive effects on <i>Sphagnum</i> growth and defense. In both species, drought without herbivory reduced the phenolics in leachate, but with herbivory increased phenolics, indicating a synergistic effect between herbivory and drought on <i>Sphagnum</i> defense. Both stressors significantly decreased biomass production, with the combined stress having a more negative effect. Interestingly, a growth–defense trade-off was found in the drought treatment of both <i>Sphagnum</i> species, but disappeared in the wet treatment. Conversely, a trade-off between soluble sugars and phenolics was found in the wet but not in the drought treatment, suggesting that soluble sugars may play a role in inducing the defense and hence mask the growth–defense trade-off in peat mosses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our results emphasize that predicting the impact of combined stressors on peat moss traits is complex and challenging. Future models should account for the effects of multiple environmental stressors to guide peatland conservation under climate warming.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 11","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456037","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}

{"title":"Scent-mediated bee pollination and myrmecochory in an enigmatic geophyte with pyrogenic flowering and subterranean development of fleshy fruits","authors":"Ian Kiepiel,&nbsp;Steven D. Johnson","doi":"10.1002/ajb2.16421","DOIUrl":"10.1002/ajb2.16421","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Volatile emissions from flowers and fruits play a key role in signalling to animals responsible for pollination and seed dispersal. Here, we investigated the pollination biology and chemical ecology of reproduction in <i>Apodolirion buchananii</i>, an African amaryllid that flowers in a leafless state soon after grassland vegetation is burnt in the dry late-winter season.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Pollinators were identified through field collection and pollen loads were quantified. Floral traits including spectral reflectance and scent chemistry were documented. Bioassays using cup traps were used to test the function of floral volatiles. Fruiting biology was investigated using controlled hand-pollination experiments and chemical analysis of fruit scent. Seed germination was scored in greenhouse trials. Seed dispersal was monitored using observations and camera trapping.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The sweetly scented white flowers of <i>A. buchananii</i> are pollen-rewarding and pollinated mainly by a diverse assemblage of bees. Cup-trap experiments demonstrated that pollinators are attracted to phenylacetaldehyde, the dominant volatile in the floral scent. Plants are shown to be self-incompatible, and the fleshy fruits were found to emerge from the soil six months after pollination during the peak of the summer rains. Fruits emit a diverse blend of aliphatic and aromatic esters and contain large fleshy recalcitrant seeds which germinate within days of fruits splitting open. Seed dispersal by ants was recorded.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This first account of the reproductive biology of a species in the genus <i>Apodolirion</i> highlights an outcrossing mating system involving bees attracted to color and scent as well as the unusual fruiting biology and ant-mediated system of seed dispersal.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 11","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11584040/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456042","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}

{"title":"The roles of root-nodulating bacterial associations and cyanogenesis in the freezing sensitivities of herbaceous legumes","authors":"Samuel L. Rycroft,&nbsp;Hugh A. L. Henry","doi":"10.1002/ajb2.16424","DOIUrl":"10.1002/ajb2.16424","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Reduced snow cover and increasing temperature variability can increase freezing stress for herbaceous plants in northern temperate regions. Legumes have emerged as a plant functional group that is highly sensitive to these changes relative to other herbaceous species in these regions. We explored root-nodulating bacterial associations and cyanogenesis as potential mechanisms explaining this relatively low freezing tolerance of legumes.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>To examine the influence of bacterial associations, we grew four legume species with or without crushed-nodule inoculum at three severities of freezing, and three concentrations of nitrogen to disambiguate the direct benefits of increased nitrogen from the total bacterial effect. We quantified cyanogenesis via hydrogen cyanide production in both true leaves and cotyledons for nine legume species.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Root nodulation generally only affected legume survival under low nitrogen, when freezing severity was moderate or low. However, for the frost-surviving plants, the growth advantage provided by nodulation decreased (it was often no longer significant with increasing freezing severity), and greater freezing severity reduced total nodule mass. In contrast, cyanogenesis was only detected in two of the nine species.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The diminished performance of nodulated plants in response to freezing could place legumes at a competitive disadvantage and potentially explain their high sensitivity to freezing relative to other herbaceous species in northern temperate regions. Overall, this result has important implications for changes in soil fertility, community composition, and plant productivity in these ecosystems in the context of a changing winter climate.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456043","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}

{"title":"Weighing the risks and benefits of flowering early in the spring for the woody perennial Prunus pumila","authors":"Danielle A. Lake Diver,&nbsp;Jessica A. Savage","doi":"10.1002/ajb2.16417","DOIUrl":"10.1002/ajb2.16417","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>There are advantages to flowering early in the spring, including greater pollinator fidelity and longer fruit maturation time. But plant phenology has advanced in recent years, making many plants vulnerable to freezing damage from late frosts.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>To determine the costs and benefits of flowering early in the growing season, we exposed <i>Prunus pumila</i> plants to two freezing treatments and a delayed flowering treatment in subsequent years. Data were collected on ovary swelling, fruit production, and pollinator visitation on hand- and open-pollinated plants in all treatments. We also measured tissue damage after freeze events.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Our results suggest that flowering time and temperature affect reproductive success, with fewer fruits produced after hard freezes. The same was not true for light freezes, which had minimal impact on reproduction. Freezing damage to plants after a hard freeze did affect the number of dipteran pollinators but not the overall pollinator visitation rate. Despite the clear impact of freezing temperatures on plant reproduction, flowering early provided an advantage in that reproductive output decreased with delayed flowering.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our findings suggest that <i>Prunus pumila</i> will retain the ability to attract pollinators and produce viable seeds if exposed to false spring conditions that involve a light freeze, but hard freezes may reduce yield by an order of magnitude. Although the advantages to flowering early may outweigh the risk of freezing damage under current conditions, it is possible that flower viability may be constrained under continued climate warming.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 11","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11584043/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456044","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}

{"title":"Natural and anthropogenic factors influence flowering synchrony and reproduction of a dominant plant in an inter-Andean scrub","authors":"Diego P. Vélez-Mora,&nbsp;Karla Trigueros-Alatorre,&nbsp;David H. Duncan,&nbsp;Pedro F. Quintana-Ascencio","doi":"10.1002/ajb2.16416","DOIUrl":"10.1002/ajb2.16416","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Agriculture expansion, livestock, and global change have transformed biological communities and altered, through aerosols and direct deposition, N:P balance in soils of inter-Andean valleys, potentially affecting flowering phenology of many species and thereby flowering synchrony and plant reproduction.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We evaluated the influence of variation in temperature and moisture along the local elevational gradient and treatments with the addition of N and P and grazing on flowering synchrony and reproduction of <i>Croton</i>, a dominant shrub of the inter-Andean dry scrub. Along the elevational gradient (300 m difference between the lowest and highest site), we set up plots with and without grazing nested with four nutrient treatments: control and addition of N or P alone or combined N + P. We recorded the number of female and male flowers in bloom monthly from September 2017 to August 2019 to calculate flowering synchrony. We assessed fruiting, seed mass, and pre-dispersal seed predation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Higher growing-season soil temperatures, which were negatively associated with local elevation and higher nitrogen availability promoted flowering synchrony of <i>Croton</i>, particularly among larger plants. Greater flowering synchrony, high soil temperatures, and addition of N + P resulted in production of more fruits of <i>Croton</i>, but also intensified pre-dispersal seed predation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Temperature, availability of moisture throughout the elevational gradient, and nutrient manipulation affected flowering synchrony, which subsequently affected production of fruits in <i>Croton</i>. These results emphasize the critical role of current anthropogenic changes in climate and nutrient availability on flowering synchrony and reproduction of <i>Croton</i>, a dominant plant of the inter-Andean scrub.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456041","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}

{"title":"An early cladoxylopsid with complex vascular architecture: Paracladoxylon kespekianum gen. et sp. nov. from the Lower Devonian (Emsian) of Quebec, Canada","authors":"Jessica Chu,&nbsp;Thibault Durieux,&nbsp;Alexandru M. F. Tomescu","doi":"10.1002/ajb2.16418","DOIUrl":"10.1002/ajb2.16418","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Cladoxylopsids, one of the first lineages with complex organization to rise from the plexus of structurally simple plants that comprised the earliest euphyllophyte floras, are moniliformopsid euphyllophytes. They formed Earth's earliest forests by the Middle Devonian and are thought to have given rise to the equisetopsids and probably some fern lineages. The Lower Devonian (Emsian) Battery Point Formation (Quebec, Canada) contains previously unrecognized cladoxylopsids preserved anatomically. One of these provides new data on structural evolution among euphyllophytes and is described here.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The anatomy and morphology of permineralized axes of the new plant were studied with light and electron microscopy on sections produced using the cellulose acetate peel technique. Morphological comparisons and phylogenetic analysis were used for taxonomic placement of the plant.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The plant represents a new species, <i>Paracladoxylon kespekianum</i> Chu et Tomescu, gen. et sp. nov., that has tracheids with modern-looking bordered pits and the complex cauline vascular architecture characteristic of the genus <i>Cladoxylon</i>. Its dissected ultimate appendages have complex regular taxis and a pattern of vascularization that suggests bilateral symmetry.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p><i>Paracladoxylon kespekianum</i> is one of the largest Early Devonian euphyllophytes, among the oldest representatives of the cladoxylopsid group, and older than any species of the closely related <i>Cladoxylon</i> by at least 35 million years. It is also one of the oldest anatomically preserved representatives of the cladoxylopsid group. Its anatomical organization pushes the rise of complex vascular architecture among moniliformopsid euphyllophytes deeper in time than previously recognized.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456036","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}

{"title":"Mutation rate is central to understanding evolution","authors":"Lindell Bromham","doi":"10.1002/ajb2.16422","DOIUrl":"10.1002/ajb2.16422","url":null,"abstract":"&lt;p&gt;Darwinian evolution relies on mutation as a constant source of variation, yet in evolutionary biology, mutation is often taken for granted, pushed to the background and treated as if it was random and uniform across all genes and all species. Mutation is an essential parameter in many evolutionary models, although often regarded as a “nuisance parameter” rather than the focus of interest—but mutation is a fundamental driver of evolution. Studying how rates and patterns of mutation are shaped by chance and selection is critical for understanding evolution of biodiversity, and has practical consequences for the way we use DNA to understand evolutionary history. Many evolutionary analyses—including genomics, population genetics, and phylogenetics—make simplifying assumptions about mutation rate, and the nature of these assumptions can influence the answers we get (e.g., Ritchie et al., &lt;span&gt;2022&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;Mutation rate is a balancing act, playing out at many different evolutionary levels simultaneously. At the biochemical level, single-base changes to DNA sequences result from replication errors or imperfectly repaired damage. Cells have an impressive arsenal of equipment for repairing damage and correcting errors, but repair must be “paid for” in energy and time, which could otherwise be invested in growth and reproduction (Avila and Lehmann, &lt;span&gt;2023&lt;/span&gt;). Individuals can vary in repair efficiency, or in the amount of energy available to invest in repair, and therefore in their patterns and rates of mutation. On longer timescales, lineage persistence depends on finding a balance between risk of mutation and costs of error correction and repair. Undirected changes to functional sequences are typically more likely to ruin than improve, so mutation is expected to exact a cost in terms of chances of success. If mutation rate is too high, offspring might not reliably inherit their parents’ advantageous traits, yet mutation provides the chance of generating variations that might allow individuals to better survive in a changing environment or have an increased chance of avoiding parasites and predators. If there is too little mutation, evolution grinds to a halt. If there is too much mutation, it runs into the ground, scrambling the hereditary message passed to subsequent generations and overwriting adaptations. The relative risks and benefits of mutation may vary between lineages and depend upon the environment, shifting when a lineage must adapt to changing conditions (Weng et al., &lt;span&gt;2021&lt;/span&gt;). Mutation rates are a balance between the chance of beneficial variation and the risk of destroying key genome functions. This balancing act plays out in individual lives and over evolutionary time.&lt;/p&gt;&lt;p&gt;Mutation rate is governed by the rate at which changes happen to the genome and the rate at which they are repaired, both of which vary among organisms. Considering one universal mutagen—ultraviolet (UV) light—provides a useful illustration","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16422","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142456040","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}