American Journal of Botany最新文献

{"title":"Correlated evolution of dispersal traits and habitat preference in the melicgrasses","authors":"William H. Brightly,&nbsp;Ana M. Bedoya,&nbsp;McKenzie M. Carlson,&nbsp;Maria G. Rottersman,&nbsp;Caroline A. E. Strömberg","doi":"10.1002/ajb2.16406","DOIUrl":"10.1002/ajb2.16406","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Seed dispersal is a critical process impacting individual plants and their communities. Plants have evolved numerous strategies and structures to disperse their seeds, but the evolutionary drivers of this diversity remain poorly understood in most lineages. We tested the hypothesis that the evolution of wind dispersal traits within the melicgrasses (Poaceae: Meliceae Link ex Endl.) was correlated with occupation of open and disturbed habitats.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>To evaluate wind dispersal potential, we collected seed dispersal structures (diaspores) from 24 melicgrass species and measured falling velocity and estimated dispersal distances. Species’ affinity for open and disturbed habitats were recorded using georeferenced occurrence records and land cover maps. To test whether habitat preference and dispersal traits were correlated, we used phylogenetically informed multilevel models.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Melicgrasses display several distinct morphologies associated with wind dispersal, suggesting likely convergence. Open habitat taxa had slower-falling diaspores, consistent with increased wind dispersal potential. However, their shorter stature meant that dispersal distances, at a given wind speed, were not higher than those of their forest-occupying relatives. Species with affinities for disturbed sites had slower-falling diaspores and greater wind dispersal distances, largely explained by lighter diaspores.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our results are consistent with the hypothesized evolutionary relationship between habitat preference and dispersal strategy. However, phylogenetic inertia and other plant functions (e.g., water conservation) likely shaped dispersal trait evolution in melicgrasses. It remains unclear if dispersal trait changes were precipitated by or predated changing habitat preferences. Nevertheless, our study provides promising results and a framework for disentangling dispersal strategy evolution.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16406","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268182","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 phylogeny of the Triticeae: Resolution and phylogenetic conflict based on genomewide nuclear loci","authors":"Roberta J. Mason-Gamer,&nbsp;Dawson M. White","doi":"10.1002/ajb2.16404","DOIUrl":"10.1002/ajb2.16404","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>The wheat tribe, Triticeae, has been the subject of molecular phylogenetic analyses for nearly three decades, and extensive phylogenetic conflict has been apparent from the earliest comparisons among DNA-based data sets. While most previous analyses focused primarily on nuclear vs. chloroplast DNA conflict, the present analysis provides a broader picture of conflict among nuclear loci throughout the tribe.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Exon data were generated from over 1000 nuclear loci using targeted sequence capture with custom baits, and nearly complete chloroplast genome sequences were recovered. Phylogenetic conflict was assessed among the trees from the chloroplast genomes, the concatenated nuclear loci, and a series of nuclear-locus subsets guided by <i>Hordeum</i> chromosome gene maps.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>At the intergeneric level, the analyses collectively revealed a few broadly consistent relationships. However, the prevailing pattern was one of extensive phylogenetic conflict throughout the tribe, among both deep and shallow branches, and with the extent of the conflict varying among data subsets.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The results suggest continual introgression or lineage sorting within and among the named lineages of the Triticeae, shaping both deep and shallow relationships in the tribe.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16404","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268232","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":"Flower position within plants influences reproductive success both directly and via phenology","authors":"Alicia Valdés,&nbsp;Johan Ehrlén","doi":"10.1002/ajb2.16405","DOIUrl":"10.1002/ajb2.16405","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>In plants, within-individual trait variation might result from mechanisms related to ontogenetic contingency, i.e., to the position of a particular structure within the plant, previous developmental events, and/or the developmental environment. Flower position within inflorescences as well as inflorescence position within plants can influence resource provisioning, phenology, biotic interactions, and reproductive success. Despite the potential implications of within-individual variation in plant reproductive phenotypes, its causes and effects on reproductive success are still little explored.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We assessed how reproductive success, in terms of fruit and seed set, and seed predation of 5883 flowers in <i>Lathyrus vernus</i> were influenced by their position within and among racemes, to what extent relationships between flower position and reproductive success and seed predation were mediated by phenology, and if positional effects on reproductive success depended on the external environment.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>In three years, basal flowers and racemes opened earlier and had higher fruit set than distal. Basal flowers also experienced higher seed predation. Differences among racemes in fruit and seed set were largely related to phenology, while differences in fruit set, seed set, and seed predation within racemes were not. In one year, differences in fruit set among flowers at different positions depended on flowering duration.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our results highlight the important role of ontogenetic contingency for within-individual variation in phenology and reproductive success. As the spatial distribution of reproductive structures affects both within-plant trait distributions and fitness, it is a likely target for natural selection.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16405","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268231","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":"Ecological differentiation and sympatry of cryptic species in the Sphagnum magellanicum complex (Bryophyta)","authors":"Marta Nieto-Lugilde,&nbsp;Diego Nieto-Lugilde,&nbsp;Bryan Piatkowski,&nbsp;Aaron M. Duffy,&nbsp;Sean C. Robinson,&nbsp;Blanka Aguero,&nbsp;Scott Schuette,&nbsp;Richard Wilkens,&nbsp;Joseph Yavitt,&nbsp;A. Jonathan Shaw","doi":"10.1002/ajb2.16401","DOIUrl":"https://doi.org/10.1002/ajb2.16401","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p><i>Sphagnum magellanicum</i> (Sphagnaceae, Bryophyta) has been considered to be a single semi-cosmopolitan species, but recent molecular analyses have shown that it comprises a complex of at least seven reciprocally monophyletic groups, that are difficult or impossible to distinguish morphologically.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Newly developed barcode markers and RADseq analyses were used to identify species among 808 samples from 119 sites. Molecular approaches were used to assess the geographic ranges of four North American species, the frequency at which they occur sympatrically, and ecological differentiation among them. Microhabitats were classified with regard to hydrology and shade. Hierarchical modelling of species communities was used to assess climate variation among the species. Climate niches were projected back to 22,000 years BP to assess the likelihood that the North American species had sympatric ranges during the late Pleistocene.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The species exhibited parallel morphological variation, making them extremely difficult to distinguish phenotypically. Two to three species frequently co-occurred within peatlands. They had broadly overlapping microhabitat and climate niches. Barcode- versus RADseq-based identifications were in conflict for 6% of the samples and always involved <i>S. diabolicum</i> vs. <i>S. magniae</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>These species co-occur within peatlands at scales that could permit interbreeding, yet they remain largely distinct genetically and phylogenetically. The four cryptic species exhibited distinct geographic and ecological patterns. Conflicting identifications from barcode vs. RADseq analyses for <i>S. diabolicum</i> versus <i>S. magniae</i> could reflect incomplete speciation or hybridization. They comprise a valuable study system for additional work on climate adaptation.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244614","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":"Inter-archipelago dispersal, anagenetic evolution, and the origin of a rare, enigmatic plant genus on a remote oceanic archipelago","authors":"Myong-Suk Cho,&nbsp;Seon-Hee Kim,&nbsp;Philippe Danton,&nbsp;Seung-Chul Kim,&nbsp;Tod F. Stuessy,&nbsp;Daniel J. Crawford","doi":"10.1002/ajb2.16403","DOIUrl":"10.1002/ajb2.16403","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Island plants have long interested biologists because of their distinctive morphological features and their isolation on small land areas in vast oceans. Studies of insular endemics may include identifying their ancestors, tracing their dispersal to islands, and describing their evolution on islands, including characters adaptive to island life. <i>Thamnoseris</i> is a monospecific genus endemic to the Desventuradas Islands, Chile. Its origins and relationships are unresolved, given the challenges of getting to the islands and accessing plants there.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Sequences from ITS of nrDNA and the complete chloroplast genome were employed to resolve phylogenetic relationships of <i>Thamnoseris</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Phylogenetic analyses of nuclear and chloroplast sequences showed <i>Thamnoseris</i> nested within or sister to <i>Dendroseris</i>, the largest endemic genus in the Juan Fernández Islands.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p><i>Thamnoseris</i> evolved from a common ancestor of all or most species of <i>Dendroseris</i> prior to the diversification of <i>Dendroseris</i> in the Juan Fernández archipelago. The ancestor of <i>Thamnoseris</i> dispersed to the Desventuradas archipelago, which consists of the islands San Ambrosio and San Félix, within the past 3 Ma (the age of San Ambrosio). This is the only known example of possible plant dispersal between the Juan Fernández and Desventuradas Islands. We also mention two less likely biogeographic scenarios for the origin of <i>Thamnoseris</i>, which has features not seen in <i>Dendroseris</i>: small capitula with yellow florets; style branches barely divergent; and basally swollen subtending involucral bracts, all features associated with selfing and reduced dispersal. Goats and rabbits (now removed) reduced <i>T. lacerata</i>, once very abundant on the Desventuradas Islands, to several plants, making it of extreme conservation concern and worthy of further study.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185285","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":"Ocean exposure and latitude drive multiple clines within the coastal perennial ecotype of the yellow monkeyflower, Mimulus guttatus","authors":"Thomas Zambiasi,&nbsp;David B. Lowry","doi":"10.1002/ajb2.16402","DOIUrl":"10.1002/ajb2.16402","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>A key goal of evolutionary biologists is to understand how and why genetic variation is partitioned within species. In the yellow monkeyflower, <i>Mimulus guttatus</i> (syn. <i>Erythranthe guttata</i>), coastal perennial populations constitute a single genetically and morphologically differentiated ecotype compared to inland <i>M. guttatus</i> populations. While the coastal ecotype's distinctiveness has now been well documented, there is also environmental variation across the ecotype's range that could drive more continuous differentiation among its component populations.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Based on previous observations of a potential cline within this ecotype, we quantified plant height, among other traits, across coastal perennial accessions from 74 populations in a greenhouse common garden experiment. To evaluate potential drivers of the relationship between trait variation and latitude, we regressed height against multiple climatic factors, including temperature, precipitation, and coastal wind speeds. We also accounted for exposure to the open ocean in all analyses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Multiple traits were correlated with latitude of origin, but none more than plant height. Height was negatively correlated with latitude, and plants directly exposed to the open ocean were shorter than those protected from coastal winds. Further analyses revealed that height was correlated with climatic factors (precipitation, temperature, and wind speeds) that were autocorrelated with latitude. We hypothesize that one or more of these climatic factors drove the evolution of latitudinal clinal variation within the coastal ecotype.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Overall, our study illustrates the complexity of how the distribution of environmental variation can simultaneously drive the evolution of both distinct ecotypes <i>and</i> continuous clines within those ecotypes.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16402","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142144960","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":"Tracking climate vulnerability across spatial distribution and functional traits in Magnolia gentryi in the Peruvian tropical montane cloud forest","authors":"Ernesto C. Rodríguez-Ramírez,&nbsp;Frank Arroyo,&nbsp;Fressia N. Ames-Martínez,&nbsp;Agustina Rosa Andrés-Hernández","doi":"10.1002/ajb2.16400","DOIUrl":"10.1002/ajb2.16400","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Understanding the responses of functional traits in tree species to climate variability is essential for predicting the future of tropical montane cloud forest (TMCF) tree species, especially in Andean montane environments where fog pockets act as moisture traps.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We studied the distribution of <i>Magnolia gentryi</i>, measured its spatial arrangement, identified local hotspots, and evaluated the extent to which climate-related factors are associated with its distribution. We then analyzed the variation in 13 functional traits of <i>M</i>. <i>gentryi</i> and the relationship with climate.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Andean TMCF climatic factors constrain <i>M. gentryi</i> spatial distribution with significant patches or gaps that are associated with high precipitation and mean minimum temperature. The functional traits of <i>M</i>. <i>gentryi</i> are limited by the Andean TMCF climatic factors, resulting in reduced within-species variation in traits associated with water deficit.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The association between functional traits and climate oscillation is crucial for understanding the growth conditions of relict-endemic species and is essential for conservation efforts. Forest trait diversity and species composition change because of fluctuations in hydraulic safety-efficiency gradients.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16400","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142139038","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":"Tangled webs and spider-flowers: Phylogenomics, biogeography, and seed morphology inform the evolutionary history of Cleomaceae","authors":"Theresa C. Saunders,&nbsp;Isabel Larridon,&nbsp;William J. Baker,&nbsp;Russell L. Barrett,&nbsp;Félix Forest,&nbsp;Elaine Françoso,&nbsp;Olivier Maurin,&nbsp;Saba Rokni,&nbsp;Eric H. Roalson","doi":"10.1002/ajb2.16399","DOIUrl":"10.1002/ajb2.16399","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Cleomaceae is an important model clade for studies of evolutionary processes including genome evolution, floral form diversification, and photosynthetic pathway evolution. Diversification and divergence patterns in Cleomaceae remain tangled as research has been restricted by its worldwide distribution, limited genetic sampling and species coverage, and a lack of definitive fossil calibration points.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We used target sequence capture and the Angiosperms353 probe set to perform a phylogenetic study of Cleomaceae. We estimated divergence times and biogeographic analyses to explore the origin and diversification of the family. Seed morphology across extant taxa was documented with multifocal image-stacking techniques and morphological characters were extracted, analyzed, and compared to fossil records.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We recovered a well-supported and resolved phylogenetic tree of Cleomaceae generic relationships that includes 236 (~86%) species. We identified 11 principal clades and confidently placed <i>Cleomella</i> as sister to the rest of the family. Our analyses suggested that Cleomaceae and Brassicaceae diverged ~56 mya, and Cleomaceae began to diversify ~53 mya in the Palearctic and Africa. Multiple transatlantic disjunct distributions were identified. Seeds were imaged from 218 (~80%) species in the family and compared to all known fossil species.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our results represent the most comprehensive phylogenetic study of Cleomaceae to date. We identified transatlantic disjunctions and proposed explanations for these patterns, most likely either long-distance dispersals or contractions in latitudinal distributions caused by climate change over geological timescales. We found that seed morphology varied considerably but mostly mirrored generic relationships.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16399","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142103575","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 non-flowering plants of a near-polar forest in East Gondwana, Tasmania, Australia, during the Early Eocene Climatic Optimum","authors":"Miriam A. Slodownik","doi":"10.1002/ajb2.16398","DOIUrl":"10.1002/ajb2.16398","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>The Cenozoic Macquarie Harbour Formation (MHF) hosts one of the oldest and southernmost post-Cretaceous fossil plant assemblages in Australia. Coinciding with the Early Eocene Climatic Optimum (EECO) and predating the breakup of Australia from Antarctica, it offers critical data to study the diversity and extent of the Austral Polar Forest Biome, and the floristic divergence between Australasia and South America resulting from the Gondwana breakup.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The micromorphology and macromorphology of new fossil plant compressions from the MHF were described and systematically analyzed. Previously published non-flowering plant records were reviewed and revised. Macrofossil abundance data were provided. The flora was compared with other early Paleogene assemblages from across the Southern Hemisphere.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Twelve species of non-flowering plants were identified from the macrofossil record. Conifers include Araucariaceae (<i>Araucaria macrophylla</i>, <i>A. readiae</i>, <i>A. timkarikensis</i> sp. nov., and <i>Araucarioides linearis</i>), Podocarpaceae (<i>Acmopyle glabra</i>, <i>Dacrycarpus mucronatus</i>, <i>Podocarpus paralungatikensis</i> sp. nov., and <i>Retrophyllum</i> sp.), and Cupressaceae (<i>Libocedrus microformis</i>). <i>Dacrycarpus linifolius</i> was designated a junior synonym of <i>D. mucronatus</i>. Further components include a cycad (<i>Bowenia johnsonii</i>, Zamiaceae), a pteridosperm (<i>Komlopteris cenozoicus</i>, Umkomasiaceae), and a fern (<i>Lygodium dinmorphyllum</i>, Schizaeaceae).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The fossil assemblage represents a mixed near-polar forest with a high diversity of conifers. The morphology and preservation of several species indicate adaptations to life at high latitudes. The coexistence of large- and small-leaved conifers implies complex, possibly open forest structures. Comparisons with contemporaneous assemblages from Argentina support a circumpolar biome during the EECO, reaching from southern Australia across Antarctica to southern South America.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 9","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajb2.16398","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142078894","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":"Tank formation transforms nitrogen metabolism of an epiphytic bromeliad and its phyllosphere bacteria","authors":"Jade Stryker,&nbsp;Elizabeth White,&nbsp;Erika Díaz-Almeyda,&nbsp;Brian Sidoti,&nbsp;Brad Oberle","doi":"10.1002/ajb2.16396","DOIUrl":"10.1002/ajb2.16396","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Premise</h3>\u0000 \u0000 <p>Up to half of tropical forest plant species grow on other plants. Lacking access to soils, vascular epiphytes have unique adaptations for mineral nutrition. Among the most distinctive is the tank growth form of certain large bromeliads, which absorb nutrients that are cycled by complex microbial communities in water trapped among their overlapping leaf bases. However, tanks form only after years of growth by juvenile plants, which must acquire nutrients differently. Understanding how nutrient dynamics change during tank bromeliad development can provide key insights into the role of microorganisms in the maintenance of tropical forest biodiversity.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We evaluated variations in plant morphology, growth, foliar nitrogen physiology, and phyllosphere bacterial communities along a size gradient spanning the transition to tank formation in the threatened species <i>Tillandsia utriculata</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Sequential morphological and growth phases coincided with the transition to tank formation when the longest leaf on plants was between 14 and 19 cm. Before this point, foliar ammonium concentrations were very high, but after, leaf segments absorbed significantly more nitrate. Leaf-surface bacterial communities tracked ontogenetic changes in plant morphology and nitrogen metabolism, with less-diverse communities in tankless plants distinguished by a high proportion of taxa implicated in ureolysis, nitrogen fixation, and methanotrophy, whereas nitrate reduction characterized communities on individuals that could form a tank.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Coupled changes in plant morphology, physiology, and microbiome function facilitate the transition between alternative nutritional modes in tank bromeliads. Comparing bromeliads across life stages and habitats may illuminate how nitrogen-use varies across scales.</p>\u0000 </section>\u0000 </div>","PeriodicalId":7691,"journal":{"name":"American Journal of Botany","volume":"111 12","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142071827","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}