4,969 results match your criteria American journal of botany[Journal]


Water influences how seed production responds to conspecific and heterospecific pollen.

Am J Bot 2019 Apr 19. Epub 2019 Apr 19.

Department of Ecology and Evolutionary Biology, University of California Irvine, 321 Steinhaus Hall, Irvine, California, 92697-2525, USA.

Premise: Outcrossing species depend on pollen from conspecific individuals that may not be exposed to the same abiotic conditions as maternal plants. Additionally, many flowers receive heterospecific pollen, which can also influence seed production. Studies aimed to understand how abiotic conditions influence seed production tend to focus on maternal conditions and leave unexplored the effect of abiotic conditions experienced by pollen donors. Read More

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https://onlinelibrary.wiley.com/doi/abs/10.1002/ajb2.1273
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http://dx.doi.org/10.1002/ajb2.1273DOI Listing
April 2019
1 Read

Tracking temporal shifts in area, biomes, and pollinators in the radiation of Salvia (sages) across continents: leveraging anchored hybrid enrichment and targeted sequence data.

Am J Bot 2019 Apr 15;106(4):573-597. Epub 2019 Apr 15.

Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA.

Premise Of The Study: A key question in evolutionary biology is why some clades are more successful by being widespread geographically, biome diverse, or species-rich. To extend understanding of how shifts in area, biomes, and pollinators impact diversification in plants, we examined the relationships of these shifts to diversification across the mega-genus Salvia.

Methods: A chronogram was developed from a supermatrix of anchored hybrid enrichment genomic data and targeted sequence data for over 500 of the nearly 1000 Salvia species. Read More

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http://dx.doi.org/10.1002/ajb2.1268DOI Listing

Defining features of age-specific fertility and seed quality in senescing indeterminate annuals.

Am J Bot 2019 Apr 15;106(4):604-610. Epub 2019 Apr 15.

National Research Council of Italy - Institute for Sustainable Plant Protection (CNR-IPSP), Via Madonna del Piano 10, Sesto Fiorentino, 50019, Florence, Italy.

Premise Of The Study: A trade-off between fertility and offspring viability underpins plant reproductive response to sub-optimal environmental conditions. Senescence involves internal resource limitation, and it is a sub-optimal body condition. We tested if senescence affects age-specific fertility and seed viability (quality) in indeterminate annuals. Read More

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https://onlinelibrary.wiley.com/doi/abs/10.1002/ajb2.1265
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http://dx.doi.org/10.1002/ajb2.1265DOI Listing
April 2019
1 Read

Divergence in floral trait preferences between nonflower-specialized birds and insects on the Galápagos.

Am J Bot 2019 Apr 15;106(4):540-546. Epub 2019 Apr 15.

Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Global Change Research Group, Mallorca, Balearic Islands, Spain.

Premise Of The Study: The characteristic scarcity of insects on remote oceanic islands has driven nonflower-specialized vertebrates to broaden their trophic niches and explore floral resources. From our previous studies in the Galápagos, we know that native insectivorous and frugivorous birds visit a wide range of entomophilous flowers and can also act as effective pollinators. Here, we tested whether opportunistic Galápagos birds show any preference for specific floral traits, and if so, this preference differs from that of insects. Read More

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http://dx.doi.org/10.1002/ajb2.1270DOI Listing

A quick glance at noteworthy articles for April 2019.

Authors:
Amy McPherson

Am J Bot 2019 Apr 15;106(4):515-516. Epub 2019 Apr 15.

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http://dx.doi.org/10.1002/ajb2.1271DOI Listing

Placing human landscape legacies in a dynamic systems framework.

Am J Bot 2019 Apr 9;106(4):517-519. Epub 2019 Apr 9.

Miami University, 700 E. High Street, Oxford, OH, 45056, USA.

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http://dx.doi.org/10.1002/ajb2.1269DOI Listing

Species characteristics affect local extinctions.

Am J Bot 2019 Apr 8;106(4):547-559. Epub 2019 Apr 8.

Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824-6406, USA.

Premise Of The Study: Human activities threaten thousands of species with extinction. However, it remains difficult to predict extinction risk for many vulnerable species. Species traits, species characteristics such as rarity or habitat use, and phylogenetic patterns are associated with responses to anthropogenic environmental change and may help predict likelihood of extinction. Read More

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http://dx.doi.org/10.1002/ajb2.1266DOI Listing

A single loss of photosynthesis in the diatom order Bacillariales (Bacillariophyta).

Am J Bot 2019 Apr 8;106(4):560-572. Epub 2019 Apr 8.

Department of Biological Sciences, University of Arkansas, SCEN 601, Fayetteville, AR 72701,, USA.

Premise Of The Study: Loss of photosynthesis is a common and often repeated trajectory in nearly all major groups of photosynthetic eukaryotes. One small subset of "apochloritic" diatoms in the genus Nitzschia have lost their ability to photosynthesize and require extracellular carbon for growth. Similar to other secondarily nonphotosynthetic taxa, apochloritic diatoms maintain colorless plastids with highly reduced plastid genomes. Read More

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http://dx.doi.org/10.1002/ajb2.1267DOI Listing
April 2019
1 Read

Rapid changes in eastern Himalayan alpine flora with climate change.

Am J Bot 2019 Apr 1;106(4):520-530. Epub 2019 Apr 1.

Missouri Botanical Garden, 4344 Shaw Blvd, St. Louis, MO, 63110, USA.

Premise Of The Study: With biodiversity and rates of climate change among the highest, the eastern Himalaya are critical for understanding the interaction of these two variables. However, there is a dearth of longitudinal data sets that address the effects of climate change on the exceptional alpine biodiversity of the Himalaya.

Methods: We established permanent alpine vegetation monitoring plots in three mountain chains of the Hengduan Mountains, the easternmost Himalaya, which have warmed 0. Read More

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http://dx.doi.org/10.1002/ajb2.1263DOI Listing
April 2019
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Interactions of plant growth responses to spring freezing and summer drought: a multispecies comparison.

Am J Bot 2019 Apr 1;106(4):531-539. Epub 2019 Apr 1.

Department of Biology, The University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada.

Premise Of The Study: Freezing and drought both result in cellular dehydration, and similar physiological responses to these stressors may result in cross acclimation, whereby prior freezing exposure increases subsequent drought tolerance. We examined how spring freezing influences summer drought tolerance for a range of herbaceous old field species: 6 graminoids (Agrostis stolonifera, Arrhenatherum elatius, Bromus inermis, Festuca rubra, Lolium perenne, Poa compressa) and 2 forbs (Plantago lanceolata, Securigera varia), with the goal of examining the generality of cross acclimation responses.

Methods: We exposed the plants to -5°C in the spring and to a 3-week summer drought, and harvested the plants after a 3-week watering/recovery period. Read More

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http://dx.doi.org/10.1002/ajb2.1264DOI Listing
April 2019
2 Reads

A meta-analysis of whole genome duplication and the effects on flowering traits in plants.

Am J Bot 2019 Mar 22;106(3):469-476. Epub 2019 Mar 22.

Department of Biology, Syracuse University, 107 College Place, Syracuse, NY, 13244, USA.

Premise Of The Study: Polyploidy, or whole genome duplication (WGD), is common in plants despite theory suggesting that polyploid establishment is challenging and polyploids should be evolutionarily transitory. There is renewed interest in understanding the mechanisms that could facilitate polyploid establishment and explain their pervasiveness in nature. In particular, premating isolation from their diploid progenitors is suggested to be a crucial factor. Read More

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http://dx.doi.org/10.1002/ajb2.1258DOI Listing

Constituents of a mixed-ploidy population of Solidago altissima differ in plasticity and predicted response to selection under simulated climate change.

Am J Bot 2019 Mar 22;106(3):453-468. Epub 2019 Mar 22.

Department of Biology, University of Minnesota Duluth, 1035 Kirby Drive, Duluth, Minnesota, 55812, USA.

Premise Of The Study: Polyploids possess unique attributes that influence their environmental tolerance and geographic distribution. It is often unknown, however, whether cytotypes within mixed-ploidy populations are also uniquely adapted and differ in their responses to environmental change. Here, we examine whether diploids and hexaploids from a single mixed-ploidy population of Solidago altissima differ in plasticity and potential response to natural selection under conditions simulating climate change. Read More

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http://dx.doi.org/10.1002/ajb2.1257DOI Listing

Heteranthery in Clarkia: pollen performance of dimorphic anthers contradicts expectations.

Am J Bot 2019 Apr 22;106(4):598-603. Epub 2019 Mar 22.

Ecology, Evolution & Marine Biology Department, University of California Santa Barbara, Santa Barbara, California, 93105, USA.

Premise Of The Study: Wild plant species that require the services of pollen-feeding insects for reliable pollination may evolve features that attract and reward their mutualistic partners. Heterantherous species have been proposed to exhibit a "division of labor" whereby "feeding anthers" (which produce pollen that may be consumed by an insect) are distinguished from "reproductive anthers" (which produce pollen more likely to contribute to reproduction). In some heterantherous species, including Clarkia unguiculata (Onagraceae), these two anther types differ with respect to stamen length, anther size, pollen production, and pollen color. Read More

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http://dx.doi.org/10.1002/ajb2.1262DOI Listing

Calochortus gunnisonii furthers evidence for the complex genetic legacy of historical climate change in the southern Rocky Mountains.

Am J Bot 2019 Mar 22;106(3):477-488. Epub 2019 Mar 22.

School of Biological Sciences, University of Northern Colorado, 501 20th Street, Greeley, Colorado, 80639, USA.

Premise Of The Study: Climate cycles of the Quaternary have impacted plants at a global scale, leaving behind a complex genetic legacy. Species of the northern Rocky Mountains of North America were exposed to more uniform glacial patterns than the central and southern ranges, where synergistic relationships between temperature and precipitation caused differences in the timing and extent of glacier onset. We examined the genetic impacts of climate oscillations on Calochortus gunnisonii (Liliaceae) in the central and southern Rocky Mountains. Read More

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http://dx.doi.org/10.1002/ajb2.1259DOI Listing

Inbreeding depression: it's not just for population biologists.

Am J Bot 2019 Mar 21;106(3):331-333. Epub 2019 Mar 21.

Department of Biology, The Pennsylvania State University, University Park, PA, 16802, USA.

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http://dx.doi.org/10.1002/ajb2.1256DOI Listing
March 2019
1 Read

A quick glance at noteworthy articles for March 2019.

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Am J Bot 2019 Mar 21;106(3):325-326. Epub 2019 Mar 21.

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http://dx.doi.org/10.1002/ajb2.1260DOI Listing

Synchrony in fall leaf drop: chlorophyll degradation, color change, and abscission layer formation in three temperate deciduous tree species.

Am J Bot 2019 Mar 18;106(3):377-388. Epub 2019 Mar 18.

Department of Biology, Wake Forest University, Winston-Salem, NC, 27109, USA.

Premise Of The Study: Deciduous tree species remove some nutrients from their leaves during fall leaf senescence through retranslocation. Retranslocation impacts the timeline of leaf fall, amount of active chlorophyll, and overall leaf nitrogen content as fall color change occurs. Our objective was to identify interspecific differences in the timing of abscission layer formation, leaf color change, and the level of chlorophyll degradation of young trees during fall senescence. Read More

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http://dx.doi.org/10.1002/ajb2.1247DOI Listing
March 2019
2.603 Impact Factor

Extensive allopolyploidy in the neotropical genus Lachemilla (Rosaceae) revealed by PCR-based target enrichment of the nuclear ribosomal DNA cistron and plastid phylogenomics.

Am J Bot 2019 Mar 18;106(3):415-437. Epub 2019 Mar 18.

Department of Biological Sciences, University of Idaho, 875 Perimeter Drive, MS 3051, Moscow, ID, 83844-3051, USA.

Premise Of The Study: Polyploidy has been long recognized as an important force in plant evolution. Previous studies had suggested widespread occurrence of polyploidy and the allopolyploid origin of several species in the diverse neotropical genus Lachemilla (Rosaceae). Nonetheless, this evidence has relied mostly on patterns of cytonuclear discordance, and direct evidence from nuclear allelic markers is still needed. Read More

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http://dx.doi.org/10.1002/ajb2.1253DOI Listing

Model clades are vital for comparative biology, and ascertainment bias is not a problem in practice: a response to Beaulieu and O'Meara (2018).

Am J Bot 2019 Mar 18;106(3):327-330. Epub 2019 Mar 18.

Department of Ecology and Evolutionary Biology and Peabody Museum of Natural History, Yale University, New Haven, CT, 06520-8106, USA.

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http://dx.doi.org/10.1002/ajb2.1255DOI Listing

Anatomy solves the puzzle of explosive pollen release in wind-pollinated urticalean rosids.

Am J Bot 2019 Mar 15;106(3):489-506. Epub 2019 Mar 15.

Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-903, Ribeirão Preto, SP, Brazil.

Premise Of The Study: This study details the unusual synorganization of the staminate flower in wind-pollinated urticalean rosids to add the missing pieces that complete the puzzle of the explosive mechanism of pollen release in this group.

Methods: Flower buds and flowers were analyzed using light and scanning electron microscopy.

Key Results: The pistillode, stamens, and sepals form a floral apparatus that explosively releases pollen to be carried by the wind. Read More

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https://onlinelibrary.wiley.com/doi/abs/10.1002/ajb2.1254
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http://dx.doi.org/10.1002/ajb2.1254DOI Listing
March 2019
7 Reads

An allometry between seed kernel and seed coat shows greater investment in physical defense in small seeds.

Am J Bot 2019 Mar 13;106(3):371-376. Epub 2019 Mar 13.

Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan Province, 666303, China.

Premise Of The Study: Numerous studies have treated the mass of a whole seed as an integrated unit, although the components seed kernel and seed coat play different roles and are subject to different evolutionary selection pressures. In this study, we provided the first global-scale quantification of the relative biomass investments in seed coats and seed kernels. We tested the following hypotheses: there is a negative allometry between seed kernel mass and seed coat mass, and therefore, seed coat ratio (SCR) is negatively correlated with seed mass. Read More

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http://dx.doi.org/10.1002/ajb2.1252DOI Listing
March 2019
1 Read

Three-dimensional reconstruction of soybean nodules provides an update on vascular structure.

Am J Bot 2019 Mar 12;106(3):507-513. Epub 2019 Mar 12.

Department of Crop Science, North Carolina State University, Raleigh, NC, USA.

Premise Of The Study: In many cases, the functioning of a biological system cannot be correctly understood if its physical anatomy is incorrectly described. Accurate knowledge of the anatomy of soybean [Glycine max (L.) Merril] nodules and its connection with the root vasculature is important for understanding its function in supplying the plant with nitrogenous compounds. Read More

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http://doi.wiley.com/10.1002/ajb2.1249
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http://dx.doi.org/10.1002/ajb2.1249DOI Listing
March 2019
9 Reads

Being in the right place at the right time? Parallel diversification bursts favored by the persistence of ancient epizoochorous traits and hidden factors in Cynoglossoideae.

Am J Bot 2019 Mar 12;106(3):438-452. Epub 2019 Mar 12.

Departamento de Biodiversidad, Real Jardín Botánico, CSIC. Pza. de Murillo, 2, 28014, Madrid, Spain.

Premise Of The Study: Long-distance dispersal (LDD) syndromes, especially endozoochory, facilitate plant colonization of new territories that trigger diversification. However, few studies have analyzed how epizoochorous fruits influence both range distribution and diversification rates. We examined the evolutionary history of a hyperdiverse clade of Boraginaceae (subfamily Cynoglossoideae, eight tribes, ~60 genera, ~1100 species) and the evolution of fruit traits. Read More

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http://dx.doi.org/10.1002/ajb2.1251DOI Listing

Effects of body size and root to shoot ratio on foliar nutrient resorption efficiency in Amaranthus mangostanus.

Am J Bot 2019 Mar 12;106(3):363-370. Epub 2019 Mar 12.

Beijing Key Laboratory of Biodiversity and Organic Farming, Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China.

Premise Of The Study: Nutrient resorption is essential for plant nutrient conservation. Large-bodied plants potentially have large nutrient sink pools and high nutrient flux. Whether and how nutrient resorption can be regulated by plant size and biomass allocation are yet unknown. Read More

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http://dx.doi.org/10.1002/ajb2.1246DOI Listing

Phylogeography of a widespread eastern North American shrub, Viburnum lantanoides.

Am J Bot 2019 Mar 12;106(3):389-401. Epub 2019 Mar 12.

Department of Ecology and Evolutionary Biology, Yale University, P.O. Box 208106, New Haven, Connecticut, 06520, USA.

Premise Of The Study: There have been relatively few phylogeographic studies of eastern North American plants, especially of animal-dispersed shrubby species, and this leaves a significant gap in our understanding of how such species were affected by glacial events. Here, we analyzed the phylogeography of the widespread understory shrub Viburnum lantanoides.

Methods: We generated RADseq data and paleoclimatic species distribution models (SDMs) to identify the locations of refugia where V. Read More

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http://dx.doi.org/10.1002/ajb2.1248DOI Listing

Inflorescence evolution in Santalales: integrating morphological characters and molecular phylogenetics.

Am J Bot 2019 Mar 11;106(3):402-414. Epub 2019 Mar 11.

649 Lost Lake Road, Victoria, BC, V9B 6E3, Canada.

Premise Of The Study: The sandalwood order (Santalales) includes members that present a diverse array of inflorescence types, some of which are unique among angiosperms. This diversity presents not only interpretational challenges but also opportunities to test fundamental concepts in plant morphology. Here we used modern phylogenetic approaches to address the evolution of inflorescences in the sandalwood order. Read More

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http://dx.doi.org/10.1002/ajb2.1250DOI Listing
March 2019
1 Read

Evolution of RADIALIS and DIVARICATA gene lineages in flowering plants with an expanded sampling in non-core eudicots.

Am J Bot 2019 Mar 7;106(3):334-351. Epub 2019 Mar 7.

Instituto de Biología, Universidad de Antioquia, AA 1226, Cl. 67 No. 53-108, Medellín, Colombia.

Premise Of The Study: Bilateral symmetry in core eudicot flowers is established by the differential expression of CYCLOIDEA (CYC), DICHOTOMA (DICH), and RADIALIS (RAD), which are restricted to the dorsal portion of the flower, and DIVARICATA (DIV), restricted to the ventral and lateral petals. Little is known regarding the evolution of these gene lineages in non-core eudicots, and there are no reports on gene expression that can be used to assess whether the network predates the diversification of core eudicots.

Methods: Homologs of the RAD and DIV lineages were isolated from available genomes and transcriptomes, including those of three selected non-core eudicot species, the magnoliid Aristolochia fimbriata and the monocots Cattleya trianae and Hypoxis decumbens. Read More

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http://dx.doi.org/10.1002/ajb2.1243DOI Listing

Ghosts from the past: even comprehensive sampling of the native range may not be enough to unravel the introduction history of invasive species-the case of Acacia dealbata invasions in South Africa.

Am J Bot 2019 Mar 28;106(3):352-362. Epub 2019 Feb 28.

Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.

Premise Of The Study: Knowledge about the introduction history (source(s), number and size of introduction events) of an invasive species is a crucial prerequisite to understand invasion success and to facilitate effective and sustainable management approaches, especially for effective biological control. We investigated the introduction history of the Australian legume tree Acacia dealbata in South Africa. Results of this study will not only provide critical information for the management of this species in South Africa, but will also broaden our overall knowledge on the invasion ecology of this globally important invasive tree. Read More

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http://dx.doi.org/10.1002/ajb2.1244DOI Listing
March 2019
1 Read

Stem succulence controls flower and fruit production but not stem growth in the desert shrub ocotillo (Fouquieria splendens).

Am J Bot 2019 Feb;106(2):223-230

Department of Biological Sciences, University of Rhode Island, Kingston, RI, 02881, USA.

Premise Of The Study: The C desert shrub ocotillo (Fouquieria splendens) completely lacks xeromorphic leaves but is uncommonly both stem succulent and repetitively drought deciduous (documented to have produced many foliation-defoliation cycles during a growing season). Both adaptations conserve water in this xerophyte, but are the roles of succulence and deciduousness merely redundant? The observation that year-to-year reproductive effort was relatively consistent while vegetative growth was not offered a critical clue that, coupled with long-term precipitation data, helped answer this question.

Methods: At two sites in the Chihuahuan Desert in southern New Mexico, United States, 22 ocotillos were studied annually for more than two decades to explore the relationships among reproductive effort, vegetative stem growth, and patterns of precipitation. Read More

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http://dx.doi.org/10.1002/ajb2.1237DOI Listing
February 2019

Fitness benefits and costs of floral advertising traits: insights from rayed and rayless phenotypes of Anacyclus (Asteraceae).

Am J Bot 2019 Feb;106(2):231-243

Centre for Functional Ecology and Department of Life Sciences, University of Coimbra, Coimbra, Portugal.

Premise Of The Study: Ray flowers commonly observed in daisies' flowering heads are a well-known example of advertising structures for enhancing pollinator attraction. Despite this, ray loss has occurred in multiple lineages, which still rely on pollinators, suggesting that rayless phenotypes could also be adaptive for animal-pollination. Here, we investigate the benefits and costs of these specialized floral advertising structures by comparing rayed and rayless phenotypes in two hybridizing closely related species. Read More

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http://dx.doi.org/10.1002/ajb2.1238DOI Listing
February 2019

Scaling of phloem hydraulic resistance in stems and leaves of the understory angiosperm shrub Illicium parviflorum.

Am J Bot 2019 Feb 21;106(2):244-259. Epub 2019 Feb 21.

Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA.

Premise Of The Study: Recent studies in canopy-dominant trees revealed axial scaling of phloem structure. However, whether this pattern is found in woody plants of the understory, the environment of most angiosperms from the ANA grade (Amborellales-Nymphaeales-Austrobaileyales), is unknown.

Methods: We used seedlings and adult plants of the understory tropical shrub Illicium parviflorum, a member of the lineage Austrobaileyales, to explore the anatomy and physiology of the phloem in their aerial parts, including changes through ontogeny. Read More

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http://dx.doi.org/10.1002/ajb2.1241DOI Listing
February 2019
1 Read

A quick glance at noteworthy articles for February 2019.

Authors:

Am J Bot 2019 Feb 21;106(2):169-170. Epub 2019 Feb 21.

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http://dx.doi.org/10.1002/ajb2.1240DOI Listing
February 2019

An Akania (Akaniaceae) inflorescence with associated pollen from the early Miocene of New Zealand.

Am J Bot 2019 Feb 21;106(2):292-302. Epub 2019 Feb 21.

Department of Geology, University of Otago, P.O. Box 56, Dunedin, 9054, New Zealand.

Premise Of The Study: An Akania-like inflorescence, including flowers with in situ pollen was recovered from the remarkable Konservat-Lagerstätte lacustrine diatomite deposit at Foulden Maar, Otago indicating the presence of Akaniaceae in southern New Zealand during the early Miocene. The flowers, although slightly smaller than the sole modern Australian species, A. bidwillii, contain pollen grains that are very like that taxon. Read More

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http://dx.doi.org/10.1002/ajb2.1236DOI Listing
February 2019
1 Read

A decade of flowering phenology of the keystone saguaro cactus (Carnegiea gigantea).

Am J Bot 2019 Feb 21;106(2):199-210. Epub 2019 Feb 21.

USA National Phenology Network, National Coordinating Office, Tucson, Arizona, 85721.

Premise Of The Study: Phenology is the study of biological life cycle events, such as flowering and migration. Climate patterns can alter these life history events, having ecosystem-wide ramifications. For example, warmer springs are associated with earlier leaf-out for many species, impacting species interactions and growing-season carbon dynamics. Read More

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http://dx.doi.org/10.1002/ajb2.1231DOI Listing
February 2019

Divergent gene expression levels between diploid and autotetraploid Tolmiea relative to the total transcriptome, the cell, and biomass.

Am J Bot 2019 Feb 19;106(2):280-291. Epub 2019 Feb 19.

Florida Museum of Natural History, University of Florida, Gainesville, FL, 32611, USA.

Premise Of The Study: Studies of gene expression and polyploidy are typically restricted to characterizing differences in transcript concentration. Using diploid and autotetraploid Tolmiea, we present an integrated approach for cross-ploidy comparisons that account for differences in transcriptome size and cell density and make multiple comparisons of transcript abundance.

Methods: We use RNA spike-in standards in concert with cell size and density to identify and correct for differences in transcriptome size and compare levels of gene expression across multiple scales: per transcriptome, per cell, and per biomass. Read More

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http://dx.doi.org/10.1002/ajb2.1239DOI Listing
February 2019

Repeated evolution of a morphological novelty: a phylogenetic analysis of the inflated fruiting calyx in the Physalideae tribe (Solanaceae).

Am J Bot 2019 Feb 19;106(2):270-279. Epub 2019 Feb 19.

Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, 80305, USA.

Premise Of The Study: The evolution of novel fruit morphologies has been integral to the success of angiosperms. The inflated fruiting calyx, in which the balloon-like calyx swells to completely surround the fruit, has evolved repeatedly across angiosperms and is postulated to aid in protection and dispersal. We investigated the evolution of this trait in the tomatillos and their allies (Physalideae, Solanaceae). Read More

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http://dx.doi.org/10.1002/ajb2.1242DOI Listing
February 2019

Microscale trait-environment associations in two closely-related South African shrubs.

Am J Bot 2019 Feb 15;106(2):211-222. Epub 2019 Feb 15.

Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269, USA.

Premise Of The Study: Plant traits are often associated with the environments in which they occur, but these associations often differ across spatial and phylogenetic scales. Here we study the relationship between microenvironment, microgeographical location, and traits within populations using co-occurring populations of two closely related evergreen shrubs in the genus Protea.

Methods: We measured a suite of functional traits on 147 plants along a single steep mountainside where both species occur, and we used data-loggers and soil analyses to characterize the environment at 10 microsites spanning the elevational gradient. Read More

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http://dx.doi.org/10.1002/ajb2.1234DOI Listing
February 2019
1 Read

Non-native insects dominate daytime pollination in a high-elevation Hawaiian dryland ecosystem.

Am J Bot 2019 Feb 15;106(2):313-324. Epub 2019 Feb 15.

Institute of Pacific Islands Forestry, USDA Forest Service, Hilo, Hawaii, 96720, USA.

Premise Of The Study: Over one-third of the native flowering plant species in the Hawaiian Islands are listed as federally threatened or endangered. Lack of sufficient pollination could contribute to reductions in populations, reproduction, and genetic diversity among these species but has been little studied.

Methods: We used systematic observations and manual flower treatments to quantify flower visitation and outcrossing dependency of eight native (including four endangered) plant species in a dryland ecosystem in Hawaii: Argemone glauca, Bidens menziesii, Dubautia linearis, Haplostachys haplostachya, Sida fallax, Silene lanceolata, Stenogyne angustifolia, and Tetramolopium arenarium. Read More

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http://dx.doi.org/10.1002/ajb2.1233DOI Listing
February 2019

Rarity does not limit genetic variation or preclude subpopulation structure in the geographically restricted desert forb Astragalus lentiginosus var. piscinensis.

Am J Bot 2019 Feb 14;106(2):260-269. Epub 2019 Feb 14.

Department of Biology, University of Nevada, Reno, NV, USA.

Premise Of The Study: Characteristics of rare taxa include small population sizes and limited geographical ranges. The genetic consequences of rarity are poorly understood for most taxa. A small geographical range could result in reduced opportunity for isolation by distance or environment, thereby limiting genetic structure and variation, but few studies explore genetic structure at small spatial scales with sufficient resolution to test this hypothesis. Read More

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http://dx.doi.org/10.1002/ajb2.1235DOI Listing
February 2019

Biomechanical control of beech pole verticality (Fagus sylvatica) before and after thinning: theoretical modelling and ground-truth data using terrestrial LiDAR.

Am J Bot 2019 Feb 11;106(2):187-198. Epub 2019 Feb 11.

Université de Lorraine, AgroParisTech, INRA, UMR Silva, F-54000, Nancy, France.

Premise Of The Study: Thinning is a frequent disturbance in managed forests, especially to increase radial growth. Due to buckling and bending risk associated with height and mass growth, tree verticality is strongly constrained in slender trees growing in dense forests and poor light conditions. Tree verticality is controlled by uprighting movements implemented from local curvatures induced by wood maturation stresses and/or eccentric radial growth. Read More

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http://dx.doi.org/10.1002/ajb2.1228DOI Listing
February 2019

Testing the hypothesis of loss of defenses on islands across a wide latitudinal gradient of Periploca laevigata populations.

Am J Bot 2019 Feb 11;106(2):303-312. Epub 2019 Feb 11.

Departamento de Biodiversidad Molecular y Banco de ADN, Jardín Botánico Canario 'Viera y Clavijo' - Unidad Asociada CSIC, Cabildo de Gran Canaria, Camino del Palmeral 15 de Tafira Alta, 35017, Las Palmas de Gran Canaria, Spain.

Premise Of The Study: We tested a hypothesis that predicts loss of chemical defenses on island plant populations (LCDIH) as an evolutionary response to limited herbivore pressures.

Methods: Using a common garden approach, we grew 16 populations (N = 286 seedlings) of Periploca laevigata, a Mediterranean shrub for which previous studies suggested that animal browsing elicits defensive responses mediated by tannins. Our experimental setting represented a wide latitudinal gradient (37-15°N) encompassing three island systems, virtually free of large herbivores, and three mainland areas. Read More

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http://dx.doi.org/10.1002/ajb2.1232DOI Listing
February 2019
6 Reads

Within-crown plasticity in leaf traits among the tallest conifers.

Am J Bot 2019 Feb 6;106(2):174-186. Epub 2019 Feb 6.

Department of Forestry and Wildland Resources, Humboldt State University, 1 Harpst Street, Arcata, CA, 95521, USA.

Premise Of The Study: Leaves are the sites of greatest water stress in trees and a key means of acclimation to the environment. We considered phenotypic plasticity of Pseudotsuga menziesii leaves in their ecological context, exploring responsiveness to natural gradients in water stress (indicated by sample height) and light availability (measured from hemispherical photos) to understand how leaf structure is controlled by abiotic factors in tall tree crowns.

Methods: After measuring anatomy, morphology, and carbon isotope composition (δ C) of leaves throughout crowns of P. Read More

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http://dx.doi.org/10.1002/ajb2.1230DOI Listing
February 2019
1 Read

Decrypting the phyllosphere microbiota: progress and challenges.

Am J Bot 2019 Feb 6;106(2):171-173. Epub 2019 Feb 6.

Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA.

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http://dx.doi.org/10.1002/ajb2.1229DOI Listing
February 2019
1 Read

Holantarctic diversity varies widely among genetic loci within the gametophytically allotriploid peat moss Sphagnum × falcatulum.

Am J Bot 2019 Jan 15;106(1):137-144. Epub 2019 Jan 15.

Department of Ecology, Evolution and Natural Resources, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey, 08901-8551, USA.

Premise Of The Study: The traditional approach used in analyses of population genetic data for historical inference is to average across multiple marker loci, but averaging conflates the different evolutionary signals provided by stable vs. labile markers.

Methods: We used a battery of microsatellites with a wide range of mutation/substitution rates, grouping them into two sets (stable and hypervariable) to provide a more nuanced reconstruction of the population genetics and evolutionary history of the allotriploid peat moss Sphagnum × falcatulum across three disjunct regions. Read More

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http://dx.doi.org/10.1002/ajb2.1220DOI Listing
January 2019
1 Read

Variation in the transcriptome of different ecotypes of Arabidopsis thaliana reveals signatures of oxidative stress in plant responses to spaceflight.

Am J Bot 2019 Jan 15;106(1):123-136. Epub 2019 Jan 15.

Department of Botany, University of Wisconsin-Madison, Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA.

Premise Of The Study: Spaceflight provides a unique environment in which to dissect plant stress response behaviors and to reveal potentially novel pathways triggered in space. We therefore analyzed the transcriptomes of Arabidopsis thaliana plants grown on board the International Space Station to find the molecular fingerprints of these space-related response networks.

Methods: Four ecotypes (Col-0, Ws-2, Ler-0 and Cvi-0) were grown on orbit and then their patterns of transcript abundance compared to ground-based controls using RNA sequencing. Read More

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http://dx.doi.org/10.1002/ajb2.1223DOI Listing
January 2019
1 Read

Revisiting the relative growth rate hypothesis for gymnosperm and angiosperm species co-occurrence.

Am J Bot 2019 Jan 15;106(1):101-112. Epub 2019 Jan 15.

Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Moraleda 16, Coyhaique, 5951601, Chile.

Premise Of The Study: It is unclear to what extent the co-occurrence of angiosperm and gymnosperm species in some marginal ecosystems is explained by reduced growth in angiosperms due to carbon (C) limitation and by high stress tolerance in gymnosperms associated with lack of vessels and resource conservation.

Methods: We examined growth patterns and traits associated with C balance in four evergreen angiosperm species (including one vesselless species, Drimys winteri) and three gymnosperm tree species of a cold-temperate rainforest in southern Chile. We measured the mean basal area increment for the first 50 (BAI ) and the last 10 years (BAI ), wood density, leaf lifespan, and nonstructural carbohydrate (NSC) concentrations in different organs. Read More

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http://doi.wiley.com/10.1002/ajb2.1221
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http://dx.doi.org/10.1002/ajb2.1221DOI Listing
January 2019
10 Reads

Asynchrony between ant seed dispersal activity and fruit dehiscence of myrmecochorous plants.

Am J Bot 2019 Jan 15;106(1):71-80. Epub 2019 Jan 15.

Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada.

Premise Of The Study: Phenological mismatch has received attention in plant-pollinator interactions, but less so in seed dispersal mutualisms. We investigated whether the seasonal availability of myrmecochorous seeds is well matched to the seasonal activity patterns of seed-dispersing ants.

Methods: We compared seasonal timing of seed removal by a keystone seed-dispersing ant, Aphaenogaster rudis, and fruit dehiscence of several species of plants whose seeds it disperses in a deciduous forest in southern Ontario, Canada. Read More

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http://dx.doi.org/10.1002/ajb2.1214DOI Listing
January 2019
2 Reads

Inter- and intraspecific competition and shade avoidance in the carnivorous pale pitcher plant in a nutrient-poor savanna.

Authors:
J Stephen Brewer

Am J Bot 2019 Jan 14;106(1):81-89. Epub 2019 Jan 14.

Department of Biology, University of Mississippi, University, Mississippi, 38677-1848, USA.

Premise Of The Study: Ecologists generally agree that weak interspecific competition for light contributes to high plant species diversity in ecosystems with nutrient-poor soils. However, the role of competition for light in such ecosystems that are also maintained by fire is poorly understood. I quantified intra- and interspecific competition for light in a fire-maintained nutrient-poor pine savanna by contrasting the effects of conspecific and heterospecific neighbors of the pale pitcher plant, Sarracenia alata. Read More

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http://dx.doi.org/10.1002/ajb2.1219DOI Listing
January 2019
1 Read

What makes a weed a weed? A large-scale evaluation of arable weeds through a functional lens.

Am J Bot 2019 Jan 11;106(1):90-100. Epub 2019 Jan 11.

Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175 CNRS - Université de Montpellier - Université Paul Valéry - EPHE, 34293, Montpellier, France.

Premise Of The Study: Despite long-term research efforts, a comprehensive perspective on the ecological and functional properties determining plant weediness is still lacking. We investigated here key functional attributes of arable weeds compared to non-weed plants, at large spatial scale.

Methods: We used an intensive survey of plant communities in cultivated and non-cultivated habitats to define a pool of plants occurring in arable fields (weeds) and one of plants occurring only in open non-arable habitats (non-weeds) in France. Read More

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http://doi.wiley.com/10.1002/ajb2.1213
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http://dx.doi.org/10.1002/ajb2.1213DOI Listing
January 2019
14 Reads

Weather cues associated with masting behavior dampen the negative autocorrelation between past and current reproduction in oaks.

Am J Bot 2019 Jan 11;106(1):51-60. Epub 2019 Jan 11.

Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA, 92697.

Premise Of The Study: The influence of weather conditions on masting and the ecological advantages of this reproductive behavior have been the subject of much interest. Weather conditions act as cues influencing reproduction of individual plants, and similar responses expressed across many individuals lead to population-level synchrony in reproductive output. In turn, synchrony leads to benefits from economies of scale such as enhanced pollination success and seed predator satiation. Read More

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http://doi.wiley.com/10.1002/ajb2.1210
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http://dx.doi.org/10.1002/ajb2.1210DOI Listing
January 2019
8 Reads