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American Journal of Botany

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https://www.readbyqxmd.com/read/28325832/physiological-effects-of-temperature-do-not-explain-prevalence-of-females-in-populations-of-gynodioecious-lobelia-siphilitica-growing-in-warmer-climates
#1
Maia F Bailey, Andrea L Case, Christina M Caruso
PREMISE OF THE STUDY: Gynodioecy is a sexual polymorphism whereby female and hermaphroditic plants co-occur within populations. In many gynodioecious species, stressful abiotic environments are associated with higher frequencies of females. This association suggests that abiotic stress affects the relative fitness of females and hermaphrodites and, thus, the maintenance of gynodioecy. METHODS: To test whether abiotic stress affects the fitness of females and hermaphrodites, we grew open-pollinated Lobelia siphilitica families in temperature regimes characteristic of the southern portion of the species' range (where females are common) and the northern portion of the range (where females are rare)...
March 21, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28325831/landscape-genomic-insights-into-the-historic-migration-of-mountain-hemlock-in-response-to-holocene-climate-change
#2
Jeremy S Johnson, Keith D Gaddis, David M Cairns, Kranti Konganti, Konstantin V Krutovsky
PREMISE OF THE STUDY: Untangling alternative historic dispersal pathways in long-lived tree species is critical to better understand how temperate tree species may respond to climatic change. However, disentangling these alternative pathways is often difficult. Emerging genomic technologies and landscape genetics techniques improve our ability to assess these pathways in natural systems. We address the question to what degree have microrefugial patches and long-distance dispersal been responsible for the colonization of mountain hemlock (Tsuga mertensiana) on the Alaskan Kenai Peninsula...
March 21, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28325830/into-africa-molecular-phylogenetics-and-historical-biogeography-of-sub-saharan-african-woodferns-dryopteris
#3
Emily B Sessa, Aino Juslén, Henry Väre, Sally M Chambers
PREMISE OF THE STUDY: Our goal was to infer the phylogenetic relationships and historical biogeography of the genus Dryopteris with a focus on taxa in sub-Saharan Africa and neighboring islands. In general, little is known about the relationships between African fern species and their congeners in other geographic regions, and our aim was to determine whether the sub-Saharan African species of Dryopteris are monophyletic and evolved within Africa or arrived there via repeated dispersals into Africa from other regions...
March 21, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28325829/effects-of-seed-density-and-proximity-to-refuge-habitat-on-seed-predation-rates-for-a-rare-and-a-common-lupinus-species
#4
Eleanor A Pardini, Melissa V Patten, Tiffany M Knight
PREMISE OF THE STUDY: Biotic interactions such as seed predation can play a role in explaining patterns of abundance among plant species. The effect of seed predation will depend on how the strength of predation differs across species and environments, and on the degree to which seed loss at one life-cycle phase increases fitness at another phase. Few studies have simultaneously quantified predispersal and postdispersal predation in co-occurring rare and common congeners, despite the value of estimating both for understanding causes of rarity...
March 21, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28298377/nectar-properties-and-the-role-of-sunbirds-as-pollinators-of-the-golden-flowered-tea-camellia-petelotii
#5
Shi-Guo Sun, Zhi-Huan Huang, Zhi-Bao Chen, Shuang-Quan Huang
PREMISE OF THE STUDY: Properties of floral nectar have been used to predict if a plant species is pollinated by birds. To see whether winter-flowering plants evolve nectar properties corresponding to bird pollinators, nectar properties of several Camellia species (including the golden-flowered tea), as well as the role of floral visitors as effective pollinators, were examined. METHODS: Potential pollinators of Camellia petelotii were identified at different times of day and under various weather conditions...
March 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28298376/floral-size-and-shape-evolution-following-the-transition-to-gender-dimorphism
#6
Ambika Kamath, Rachel A Levin, Jill S Miller
PREMISE OF THE STUDY: Floral morphology is expected to evolve following the transition from cosexuality to gender dimorphism in plants, as selection through male and female function becomes dissociated. Specifically, male-biased dimorphism in flower size can arise through selection for larger flowers through male function, selection for smaller flowers through female function, or both. The evolutionary pathway to floral dimorphism can be most effectively reconstructed in species with intraspecific variation in sexual system...
March 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28274947/evolution-of-woody-life-form-on-tropical-mountains-in-the-tribe-spermacoceae-rubiaceae
#7
Suman Neupane, Paul O Lewis, Steven Dessein, Hunter Shanks, Sushil Paudyal, Frederic Lens
PREMISE OF THE STUDY: Spermacoceae are mainly an herbaceous group in the Rubiaceae. However, a few lineages are woody and are found in a diverse range of habitat types. Three of the largest woody lineages (Arcytophyllum, Hedyotis, and Kadua) are characterized by their distribution in the moist tropical mountains and have disjunct distribution patterns with respect to their closest relatives. In this study, we explore the cases of derived woodiness in these three lineages and their diversification dynamics in the tropical mountains of Asia, the Pacific, and the Americas...
March 8, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28274946/ontogeny-and-the-process-of-biomineralization-in-the-trichomes-of-loasaceae
#8
Adeel Mustafa, Hans-Jürgen Ensikat, Maximilian Weigend
PREMISE OF THE STUDY: South American Loasaceae have a morphologically complex trichome cover, which is characterized by multiple biomineralization. The current study investigates the ontogeny of these complex trichomes and the process of their biomineralization, since both are very poorly understood. METHODS: The development of stinging trichomes on various parts of the plants and the process of mineralization were studied using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX)...
March 8, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28232316/causes-of-ecological-gradients-in-leaf-margin-entirety-evaluating-the-roles-of-biomechanics-hydraulics-vein-geometry-and-bud-packing
#9
Thomas J Givnish, Ricardo Kriebel
PREMISE OF THE STUDY: A recent commentary by Edwards et al. (Am. J. Bot. 103: 975-978) proposed that constraints imposed by the packing of young leaves in buds could explain the positive association between non-entire leaf margins and latitude but did not thoroughly consider alternative explanations. METHODS: We review the logic and evidence underlying six major hypotheses for the functional significance of marginal teeth, involving putative effects on (1) leaf cooling, (2) optimal support and supply of the areas served by major veins, (3) enhanced leaf-margin photosynthesis, (4) hydathodal function, (5) defense against herbivores, and (6) bud packing...
February 22, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28213348/the-plant-economic-spectrum-in-bryophytes-a-comparative-study-in-subalpine-forest
#10
Zhe Wang, Xin Liu, Maaike Y Bader, Defeng Feng, Weikai Bao
PREMISE OF THE STUDY: Tradeoffs among functional traits of vascular plants are starting to be better understood, but it is unclear whether bryophytes possess similar tradeoffs or how trait relationships, or the 'economic spectrum', differ between the two groups. METHODS: We determined functional-trait values [including shoot mass per area (SMA), light-saturated assimilation rate (Amass), dark respiration rate (Rdmass), N and P concentrations (Nmass and Pmass), and photosynthetic N and P use efficiency (PNUE and PPUE)] and their bivariate relationships for 28 bryophytes growing in a subalpine old-growth fir forest on the eastern Tibetan Plateau...
February 17, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28213347/a-new-cheirolepidiaceae-coniferales-from-the-early-jurassic-of-patagonia-argentina-reconciling-the-records-of-impression-and-permineralized-fossils
#11
Ignacio Escapa, Andrew Leslie
PREMISE OF THE STUDY: Plants preserved in different fossil modes provide complementary data concerning the paleobiology and evolutionary relationships among plant groups. New material from the Early Jurassic of Patagonia shows the importance of combining these sources of information, as we describe the first compression/impression fossils of Pararaucaria, a genus of the extinct conifer family Cheirolepidiaceae previously known from permineralized fossils. These fossils extend the temporal range of this genus and may allow its wider recognition in the fossil record...
February 17, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28202456/inconsistent-intraspecific-pattern-in-leaf-life-span-along-nitrogen-supply-gradient
#12
Shimpei Oikawa, Koya Suno, Noriyuki Osada
PREMISE OF THE STUDY: Leaf life span (LLS) has long been hypothesized to plastically increase with decreasing nitrogen (N) supply from soil to maximize N retention, carbon assimilation, and fitness; however, accumulating evidence shows no consistent trend. The apparent inconsistencies are explained by a recent model that assumes LLS has a hump-shaped quadratic response to the N-supply gradient. The available evidence mostly originates from comparisons of LLS at only two levels of N availability, and the hypothesis remains unanswered...
February 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28202455/in-the-interface-of-caesalpinioids-and-mimosoids-comparative-floral-development-elucidates-shared-characters-in-dimorphandra-mollis-and-pentaclethra-macroloba-leguminosae
#13
Thais C De Barros, Giseli D Pedersoli, Juliana V Paulino, Simone P Teixeira
PREMISE OF THE STUDY: Pentaclethra and Dimorphandra (Leguminosae) have long been considered a possible enigmatic link between caesalpinioids and mimosoids because they both have an imbricate calyx and heteromorphic androecium, floral features that are rare among mimosoids but common among caesalpinioids. This study compared the developing flowers of Dimorphandra mollis and Pentaclethra macroloba to determine whether the shared floral conditions also have the same ontogenetic origin. METHODS: Buds of different sizes and flowers were processed for surface (scanning electron microscopy) and histological (light microscopy) examination...
February 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28202454/pollinator-mediated-interactions-in-experimental-arrays-vary-with-neighbor-identity
#14
Melissa K Ha, Christopher T Ivey
PREMISE OF THE STUDY: Local ecological conditions influence the impact of species interactions on evolution and community structure. We investigated whether pollinator-mediated interactions between coflowering plants vary with plant density, coflowering neighbor identity, and flowering season. METHODS: We conducted a field experiment in which flowering time and floral neighborhood were manipulated in a factorial design. Early- and late-flowering Clarkia unguiculata plants were placed into arrays with C...
February 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28202453/parenchymatous-cell-division-characterizes-the-fungal-cortex-of-some-common-foliose-lichens
#15
William B Sanders, Asunción de Los Ríos
PREMISE OF THE STUDY: Lichen-forming fungi produce diverse vegetative tissues, some closely resembling those of plants. Yet it has been repeatedly affirmed that none is a true parenchyma, in which cellular compartments are subdivided from all adjacent neighbors by cross walls adjoining older cross walls. METHODS: Using transmission electron microscopy (TEM), we tested this assumption by examining patterns of septum formation in the parenchyma-like cortex of three lichens of different phylogenetic affinities: Sticta canariensis, Leptogium cyanescens, and Endocarpon pusillum...
February 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28202452/entire-plastid-phylogeny-of-the-carrot-genus-daucus-apiaceae-concordance-with-nuclear-data-and-mitochondrial-and-nuclear-dna-insertions-to-the-plastid
#16
David M Spooner, Holly Ruess, Massimo Iorizzo, Douglas Senalik, Philipp Simon
PREMISE OF THE STUDY: We explored the phylogenetic utility of entire plastid DNA sequences in Daucus and compared the results with prior phylogenetic results using plastid and nuclear DNA sequences. METHODS: We used Illumina sequencing to obtain full plastid sequences of 37 accessions of 20 Daucus taxa and outgroups, analyzed the data with phylogenetic methods, and examined evidence for mitochondrial DNA transfer to the plastid (DcMP). KEY RESULTS: Our phylogenetic trees of the entire data set were highly resolved, with 100% bootstrap support for most of the external and many of the internal clades, except for the clade of D...
February 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28202451/losing-one-s-touch-evolution-of-the-touch-sensitive-stigma-in-the-mimulus-guttatus-species-complex
#17
Jannice Friedman, Katherine S Hart, Meghan C den Bakker
PREMISE OF THE STUDY: The stigmas of several species are touch sensitive and respond to pressure by closing. Previous research suggests that stigma closure could prevent self pollination within a flower during a pollinator's visit or enhance male function by increasing pollen export. Both factors could be favored in outcrossers, and neither would be beneficial in selfers. METHODS: We investigated variation in stigma-closing and the duration of closure in annual and perennial populations of the variable species Mimulus guttatus and whether four closely related selfing species (M...
February 15, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28183834/grass-plastomes-reveal-unexpected-paraphyly-with-endemic-species-of-micrairoideae-from-india-and-new-haplotype-markers-in-arundinoideae
#18
Melvin R Duvall, Shrirang R Yadav, Sean V Burke, William P Wysocki
PREMISE OF THE STUDY: We investigated the little-studied Arundinoideae/Micrairoideae clade of grasses with an innovative plastome phylogenomic approach. This method gives robust results for taxa of uncertain phylogenetic placement. Arundinoideae comprise ∼45 species, although historically was much larger. Arundinoideae is notable for the widely invasive Phragmites australis. Micrairoideae comprise nine genera and ∼200 species. Some are threatened with extinction, including Hubbardia, some Isachne spp...
February 9, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28183833/cytogeography-of-the-subalpine-marsh-marigold-polyploid-complex-caltha-leptosepala-s-l-ranunculaceae
#19
Keir M Wefferling, Sílvia Castro, João Loureiro, Mariana Castro, Daniela Tavares, Sara B Hoot
PREMISE OF THE STUDY: Unrecognized variation in ploidy level can lead to an underestimation of species richness and a misleading delineation of geographic range. Caltha leptosepala (Ranunculaceae) comprises a complex of hexaploids (6x), rare nonaploids (9x), and dodecaploids (12x), all with unknown distributions. We delineate the geographic distribution and contact zones of the cytotypes, investigate morphologies of cytotypes and subspecies, and discuss the biogeography and evolutionary history of the polyploid complex...
February 9, 2017: American Journal of Botany
https://www.readbyqxmd.com/read/28183832/molecular-bases-for-phyllomorph-development-in-a-one-leaf-plant-monophyllaea-glabra
#20
Naoko Ishikawa, Hirokazu Takahashi, Mikio Nakazono, Hirokazu Tsukaya
PREMISE OF THE STUDY: The aboveground part of one-leaf plants (Gesneriaceae) consists of a unique shoot-like unit called a phyllomorph, which is composed of a growing lamina and one petiolode (a stem- and petiole-like organ). The phyllomorph has three meristems: a basal meristem (BM; involved in lamina growth), a petiolode meristem (PM; required for midrib and petiolode growth), and a groove meristem (GM; contributes to inflorescence and new phyllomorph development). Although the GM has a tunica-corpus structure like a conventional shoot apical meristem (SAM), the vegetative GM of a one-leaf plant does not form any organ primordia and has been considered a defective or suppressed SAM...
February 9, 2017: American Journal of Botany
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