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American Journal of Botany | Page 2

James C Lendemer, Kyle G Keepers, Erin A Tripp, Cloe S Pogoda, Christy M McCain, Nolan C Kane
PREMISE: Lichens are fungi that enter into obligate symbioses with photosynthesizing organisms (algae, cyanobacteria). Traditional narratives of lichens as binary symbiont pairs have given way to their recognition as dynamic metacommunities. Basidiomycete yeasts, particularly of the genus Cyphobasidium, have been inferred to be widespread and important components of lichen metacommunities. Yet, the presence of basidiomycete yeasts across a wide diversity of lichen lineages has not previously been tested...
August 9, 2019: American Journal of Botany
Akira Yamawo, Haruna Ohsaki, James F Cahill
PREMISE: Plants generally increase root growth in areas with high nutrients in heterogeneous soils, a phenomenon called foraging precision. The physiology of this process is not well understood, but it may involve shoot-root signaling via leaf veins. If this is true, then damage to leaf veins, but not to nearby mesophyll, would reduce plant foraging precision. METHODS: To test this hypothesis, we imposed two leaf damage treatments on Plantago asiatica and Prunus jamasakura, removing either the tip of each main vein or mesophyll tissue between the veins with a 3-mm-diameter hole punch...
August 9, 2019: American Journal of Botany
Katelin D Pearson, Austin R Mast
PREMISE: Biological outliers (observations that fall outside of a previously understood norm, e.g., in phenology or distribution) may indicate early stages of a transformative change that merits immediate attention. Collectors of biodiversity specimens such as plants, fungi, and animals are on the front lines of discovering outliers, yet the role collectors currently play in providing such data is unclear. METHODS: We surveyed 222 collectors of a broad range of taxa, searched 47 training materials, and explored the use of 170 outlier terms in 75 million specimen records to determine the current state of outlier detection and documentation in this community...
August 7, 2019: American Journal of Botany
Aaron S David, Lukas P Bell-Dereske, Sarah M Emery, Brandon M McCormick, Eric W Seabloom, Jennifer A Rudgers
PREMISE: Microbial symbionts can buffer plant hosts from environmental change. Therefore, understanding how global change factors alter the associations between hosts and their microbial symbionts may improve predictions of future changes in host population dynamics and microbial diversity. Here, we investigated how one global change factor, precipitation, affected the maintenance or loss of symbiotic fungal endophytes in a C3 grass host. Specifically, we examined the distinct responses of Epichloë (vertically transmitted and systemic) and non-epichloid endophytes (typically horizontally transmitted and localized) by considering (1) how precipitation altered associations with Epichloë and non-epichloid endophytic taxa across host ontogeny, and (2) interactive effects of water availability and Epichloë on early seedling life history stages...
August 6, 2019: American Journal of Botany
Amy McPherson
No abstract text is available yet for this article.
August 1, 2019: American Journal of Botany
Karen E Samis, John R Stinchcombe, Courtney J Murren
PREMISE: Determining how species perform in novel climatic environments is essential for understanding (1) responses to climate change and (2) evolutionary consequences of biological invasions. For the vast majority of species, the number of population characteristics that will predict performance and patterns of natural selection in novel locations in the wild remains limited. METHODS: We evaluated phenological, vegetative, architectural, and fitness-related traits in experimental gardens in contrasting climates (Ontario, Canada, and South Carolina, USA) in the North American non-native distribution of Arabidopsis thaliana...
July 31, 2019: American Journal of Botany
Jacob J Hadle, F Leland Russell, James B Beck
PREMISE: Although autopolyploidy is common among dominant Great Plains grasses, the distribution of cytotypes within a given species is typically poorly understood. This study aims to establish the geographic distribution of cytotypes within buffalograss (Buchloë dactyloides) and to assess whether individual cytotypes have differing ecological tolerances. METHODS: A range-wide set of 578 B. dactyloides individuals was obtained through field collecting and sampling from herbarium specimens...
July 23, 2019: American Journal of Botany
Matheus Lopes Souza, Maria Bernadete Lovato, Marcilio Fagundes, Fernando Valladares, José Pires Lemos-Filho
PREMISE: Knowledge of intra-specific variation in seed traits and its environmental determinants is important for predicting plant responses to environmental changes. Here, we tested the hypothesis that differences in soil fertility and rainfall during specific phenological phases drive variation in seed traits in a widely distributed tree, Copaifera langsdorffii. We also tested the hypothesis that climatic heterogeneity increases within-plant variation in seed traits. METHODS: Inter- and intra-population and within-plant variation in seed mass, number, and seed size/seed number were evaluated for 50 individuals from five populations distributed along a rainfall gradient and occurring on varying soil types...
July 23, 2019: American Journal of Botany
Jill M Ekar, Donald K Price, Melissa A Johnson, Elizabeth A Stacy
PREMISE: The drivers of isolation between sympatric populations of long-lived and highly dispersible conspecific plants are not well understood. In the Hawaiian Islands, the landscape-dominant tree, Metrosideros polymorpha, displays extraordinary phenotypic differences among sympatric varieties despite high dispersibility of its pollen and seeds, thereby presenting a unique opportunity to investigate how disruptive selection alone can maintain incipient forms. Stenophyllous M. polymorpha var...
July 22, 2019: American Journal of Botany
Luis Abdala-Roberts, Teresa Quijano-Medina, Xoaquín Moreira, Carla Vázquez-González, Víctor Parra-Tabla, Jorge C Berny Mier Y Terán, Luca Grandi, Gaétan Glauser, Ted C J Turlings, Betty Benrey
PREMISE: The occurrence and amount of herbivory are shaped by bottom-up forces, primarily plant traits (e.g., defenses), and by abiotic factors. Addressing these concurrent effects in a spatial context has been useful in efforts to understand the mechanisms governing variation in plant-herbivore interactions. Still, few studies have evaluated the simultaneous influence of multiple sources of bottom-up variation on spatial variation in herbivory. METHODS: We tested to what extent chemical (phenolics, production of terpenoid glands) and physical (pubescence) defensive plant traits and climatic factors are associated with variation in herbivory by leaf-chewing insects across populations of wild cotton (Gossypium hirsutum)...
July 19, 2019: American Journal of Botany
(no author information available yet)
No abstract text is available yet for this article.
July 15, 2019: American Journal of Botany
Erandi Ramírez-Aguirre, Silvana Martén-Rodríguez, Gabriela Quesada-Avila, Mauricio Quesada, Yesenia Martínez-Díaz, Ken Oyama, Francisco J Espinosa-García
PREMISE: Closely related species occurring in sympatry may experience the negative consequences of interspecific pollen transfer if reproductive isolation (RI) barriers are not in place. We evaluated the importance of pre- and post-pollination RI barriers in three sympatric species of Achimenes (Gesneriaceae), including ecogeographic, phenological, floral isolation, self-pollination, and hybrid viability (fruit and seed set). METHODS: We recorded geographic distribution throughout species ranges and assessed flowering phenology and pollinator visitation at one site in central Mexico...
July 12, 2019: American Journal of Botany
John B Reese, Joseph H Williams
PREMISE: Male gametophytes of most seed plants deliver sperm to eggs via a pollen tube. Pollen tube growth rates (PTGRs) of angiosperms are exceptionally rapid, a pattern attributed to more effective haploid selection under stronger pollen competition. Paradoxically, whole genome duplication (WGD) has been common in angiosperms but rare in gymnosperms. Pollen tube polyploidy should initially accelerate PTGR because increased heterozygosity and gene dosage should increase metabolic rates...
July 11, 2019: American Journal of Botany
Brynne E Lazarus, Matthew J Germino, Bryce A Richardson
PREMISE: Physiological responses to temperature extremes are considered strong drivers of species' demographic responses to climate variability. Plants are typically classified as either avoiders or tolerators in their freezing-resistance mechanism, but a gradient of physiological-threshold freezing responses may exist among individuals of a species. Moreover, adaptive significance of physiological freezing responses is poorly characterized, particularly under warming conditions that relax selection on cold hardiness...
July 11, 2019: American Journal of Botany
Gretchen B North, Erin K Brinton, Marvin G Browne, Madeline G Gillman, Adam B Roddy, Tiffany L Kho, Emily Wang, Vitor A Fung, Craig R Brodersen
PREMISE: Because of its broad range in the neotropical rainforest and within tree canopies, the tank bromeliad Guzmania monostachia was investigated as a model of how varying leaf hydraulic conductance (Kleaf ) could help plants resist and recover from episodic drought. The two pathways of Kleaf , inside and outside the xylem, were also examined to determine the sites and causes of major hydraulic resistances within the leaf. METHODS: We measured leaf hydraulic conductance for plants in the field and laboratory under wet, dry, and rewetted conditions and applied physiological, anatomical, and gene expression analysis with modeling to investigate changes in Kleaf ...
July 11, 2019: American Journal of Botany
Hannah E Marx, Melissa Richards, Grahm M Johnson, David C Tank
PREMISE: At the intersection of ecology and evolutionary biology, community phylogenetics can provide insights into overarching biodiversity patterns, particularly in remote and understudied ecosystems. To understand community assembly of the high alpine flora in the Sawtooth National Forest, USA, we analyzed phylogenetic structure within and between nine summit communities. METHODS: We used high-throughput sequencing to supplement existing data and infer a nearly completely sampled community phylogeny of the alpine vascular flora...
July 10, 2019: American Journal of Botany
Angela M Walczyk, Erika I Hersch-Green
PREMISE: Although polyploidy commonly occurs in angiosperms, not all polyploidization events lead to successful lineages, and environmental conditions could influence cytotype dynamics and polyploid success. Low soil nitrogen and/or phosphorus concentrations often limit ecosystem primary productivity, and changes in these nutrients might differentially favor some cytotypes over others, thereby influencing polyploid establishment. METHODS: We grew diploid, established tetraploid, and neotetraploid Chamerion angustifolium (fireweed) in a greenhouse under low and high soil nitrogen and phosphorus conditions and different competition treatments and measured plant performance (height, biomass, flower production, and root bud production) and insect damage responses...
July 8, 2019: American Journal of Botany
Daniela Boanares, Alessandra R Kozovits, José P Lemos-Filho, Rosy M S Isaias, Ricardo R R Solar, Alexandre A Duarte, Tiago Vilas-Boas, Marcel G C França
PREMISE: Fog is a frequent event in Brazilian rupestrian field and plays an important role in the physiology of several plant species. Foliar water uptake (FWU) of fog may be fast or slow depending on the species. However, fog water may negatively affect CO2 assimilation. Thus, the interference in the water and carbon balance as a result of different strategies of FWU was evaluated to verify whether fog may mitigate possible water deficit in leaves. METHODS: Four plant species with different FWU strategies were studied in a ferruginous rupestrian field with frequent fog...
July 7, 2019: American Journal of Botany
N Ivalú Cacho, María José Monteverde-Suárez, Patrick J McIntyre
PREMISE: Ring species have long fascinated evolutionary biologists for their potential insights into lineage divergence and speciation across space. Few studies have investigated the potential for convergent or parallel evolution along the diverging fronts of ring species. We investigated a potential case of parallel floral variation in the Caribbean spurge Euphorbia tithymaloides, the only plant system with molecular support as a ring species. The terminal populations of each front, despite being the most divergent, exhibit such similar floral traits that they were originally considered each other's closest relative...
July 7, 2019: American Journal of Botany
Mervin E Pérez, Elvia J Meléndez-Ackerman, Omar A Monsegur-Rivera
PREMISE: Gesneria pauciflora is a rare, threatened plant in riparian forests. Periodic disturbances, expected in this habitat, could influence demographic dynamics on plant populations, yet their impact may not be the same across the watershed. We hypothesized that differences in disturbances between the main channel and tributaries may lead to spatial dissimilarities in population growth rate (λ), structure, and fecundity. METHODS: In the Maricao River Watershed in Puerto Rico, 1277 plants were tagged and monitored for 1...
July 7, 2019: American Journal of Botany
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