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American Journal of Botany

Andrés Elgorriaga, Ignacio H Escapa, Gar W Rothwell, Alexandru M F Tomescu, N Rubén Cúneo
PREMISE OF THE STUDY: Equisetum is the sole living representative of Sphenopsida, a clade with impressive species richness, a long fossil history dating back to the Devonian, and obscure relationships with other living pteridophytes. Based on molecular data, the crown group age of Equisetum is mid-Paleogene, although fossils with possible crown synapomorphies appear in the Triassic. The most widely circulated hypothesis states that the lineage of Equisetum derives from calamitaceans, but no comprehensive phylogenetic studies support the claim...
July 19, 2018: American Journal of Botany
Eva Dettweiler-Robinson, Robert L Sinsabaugh, Jennifer A Rudgers
PREMISE OF THE STUDY: Productivity in drylands may depend on the sensitivity of interactions between plants and biocrusts. Given future climate variability, it is essential to understand how interactions may be context-dependent with precipitation regime. Furthermore, little is known about the additional interactions of these producers with the belowground biota (e.g., roots, fungi, microarthropods). We evaluated the effect of removal (such as could occur following disturbance) and net interaction of plants and biocrusts and additionally manipulated the abiotic and biotic context...
July 16, 2018: American Journal of Botany
Daniel E Winkler, Jennifer R Gremer, Kenneth J Chapin, Melanie Kao, Travis E Huxman
PREMISE OF STUDY: Mechanisms by which invasive species succeed across multiple novel environmental contexts are poorly understood. Functional traits show promise for identifying such mechanisms, yet we lack knowledge of which functional traits are critical for success and how they vary across invaded ranges and with environmental features. We evaluated the widespread recent invasion of Sahara mustard (Brassica tournefortii) in the southwestern United States to understand the extent of functional trait variation across the invaded range and how such variation is related to spatial and climatic gradients...
July 16, 2018: American Journal of Botany
Gar W Rothwell, Michael A Millay, Ruth A Stockey
PREMISE OF THE STUDY: Recent clarification of the distribution of Marattiales through time provides the impetus for "total evidence" phylogenetic analyses of a major fern clade with a rich fossil record. These analyses serve as empirical tests for results from systematic analyses of living species and also of the belief that relationships among living species accurately reflect the overall pattern of phylogeny for clades with an extensive fossil record and a large percentage of extinction...
July 12, 2018: American Journal of Botany
Jade Lu, Nicolas Magain, Jolanta Miadlikowska, Jessica R Coyle, Camille Truong, François Lutzoni
PREMISE OF THE STUDY: Factors shaping spatiotemporal patterns of associations in mutualistic systems are poorly understood. We used the lichen-forming fungi Peltigera and their cyanobacterial partners Nostoc to investigate the spatial structure of this symbiosis at an intrabiome scale and to identify potential factors shaping these associations. METHODS: Ninety-three thalli were sampled in Québec, Canada, along a south-north and an east-west transect of ~1300 km each...
July 12, 2018: American Journal of Botany
Janis Antonovics, Jessica L Abbate, Emily L Bruns, Peter D Fields, Nicole J Forrester, Kimberly J Gilbert, Michael E Hood, Timothy Park, Douglas R Taylor
PREMISE OF THE STUDY: Plant pathogens that form persistent systemic infections within plants have the potential to affect multiple plant life history traits, yet we tend to focus only on visible symptoms. Anther smut of Silene latifolia caused by the fungus Microbotryum lychnidis-dioicae induces the anthers of its host to support fungal spore production instead of pollen, and the pathogen is primarily transmitted among flowering plants by pollinators. Nevertheless, most of its life cycle is spent in the asymptomatic vegetative phase, and spores falling on seedlings or nonflowering plants can also infect the host...
July 11, 2018: American Journal of Botany
Dubán Canal, Nils Köster, Katy E Jones, Nadja Korotkova, Thomas B Croat, Thomas Borsch
PREMISE OF THE STUDY: Philodendron is a large genus of ~560 species and among the most conspicuous epiphytic components of Neotropical forests, yet its phylogenetic relationships, timing of divergence, and diversification history have remained unclear. We present a comprehensive phylogenetic study for Philodendron and investigate its diversification, including divergence-time estimates and diversification rate shift analyses. METHODS: We performed the largest phylogenetic reconstruction for Philodendron to date, including 125 taxa with a combined dataset of three plastid regions (petD, rpl16, and trnK/matK)...
July 11, 2018: American Journal of Botany
Ana Andruchow-Colombo, Ignacio H Escapa, N Rubén Cúneo, María A Gandolfo
PREMISE OF THE STUDY: We describe a new araucarian species, Araucaria lefipanensis, from the Late Cretaceous flora of the Lefipán Formation, in Patagonia (Argentina) based on reproductive and vegetative remains, with a combination of characters that suggest mosaic evolution in the Araucaria lineage. METHODS: The studied fossils were found at the Cañadón del Loro locality. Specimens were separated into two leaf morphotypes, and their morphological differences were tested with MANOVA...
July 11, 2018: American Journal of Botany
Lillian P Hancock, Frank Obbens, Abigail J Moore, Kevin Thiele, Jurriaan M de Vos, Judy West, Joseph A M Holtum, Erika J Edwards
PREMISE OF THE STUDY: Calandrinia are small, succulent herbs that vary broadly in habitat, morphology, life history, and photosynthetic metabolism. The lineage is placed within the Montiaceae, which in turn is sister to the rest of the Portulacineae (Caryophyllales). Calandrinia occupy two distinct biogeographic regions, one in the Americas (~14 species), and one in Australia (~74 species). Past analyses of the Montiaceae present conflicting hypotheses for the phylogenetic placement and monophyly of Calandrinia, and to date, there has been no molecular phylogenetic analysis of the Australian species...
July 11, 2018: American Journal of Botany
Belén Estébanez, Nagore G Medina, Rut Caparrós, Laura Monforte, María-Ángeles Del-Castillo-Alonso, Javier Martínez-Abaigar, Encarnación Núñez-Olivera
PREMISE OF THE STUDY: Ultraviolet (UV) radiation influences the viability of algal spores and seed-plant pollen depending on the species, the dose, and the wavelength. In bryophytes, one of the dominant groups of plants in many habitats, UV radiation could determine their spore dispersal strategy, and such data are critical for reconstructing the ancestral state in plants and for determining the distribution range and persistence of bryophyte species. METHODS: Spores of four bryophyte species of the moss genus Orthotrichum that were either hygrochastic or xerochastic (spores dispersed under wet or dry conditions, respectively) were exposed to realistic doses of UV radiation under laboratory conditions...
July 9, 2018: American Journal of Botany
Christel Vidaller, Thierry Dutoit, Yosra Ibrahim, Hans Martin Hanslin, Armin Bischoff
PREMISE OF THE STUDY: Genetic differentiation in plant species may result from adaptation to environmental conditions, but also from stochastic processes. The drivers selecting for local adaptation and the contribution of adaptation to genetic differentiation are often unknown. Restoration and succession studies have revealed different colonization patterns for Brachypodium retusum, a common Mediterranean grass. In order to understand these patterns, we tested population differentiation and adaptation to different environmental factors...
July 9, 2018: American Journal of Botany
Soraya C M Leal-Bertioli, Ignácio J Godoy, João F Santos, Jeff J Doyle, Patrícia M Guimarães, Brian L Abernathy, Scott A Jackson, Márcio C Moretzsohn, David J Bertioli
PREMISE OF THE STUDY: The genetic bottleneck of polyploid formation can be mitigated by multiple origins, gene flow, and recombination among different lineages. In crop plants with limited origins, efforts to increase genetic diversity have limitations. Here we used lineage recombination to increase genetic diversity in peanut, an allotetraploid likely of single origin, by crossing with a novel allopolyploid genotype and selecting improved lines. METHODS: Single backcross progeny from cultivated peanut × wild species-derived allotetraploid cross were studied over successive generations...
July 9, 2018: American Journal of Botany
Jens-Christian Svenning
No abstract text is available yet for this article.
July 3, 2018: American Journal of Botany
Caitlin McDonough MacKenzie, Richard B Primack, Abraham J Miller-Rushing
PREMISE OF THE STUDY: Climate-driven changes in phenology are substantially affecting ecological relationships and ecosystem processes. The role of variation among species has received particular attention; for example, variation among species' phenological responses to climate can disrupt trophic interactions and can influence plant performance. Variation within species in phenological responses to climate, however, has received much less attention, despite its potential role in ecological interactions and local adaptation to climate change...
June 29, 2018: American Journal of Botany
Marta Nieto-Lugilde, Olaf Werner, Stuart F McDaniel, Petr Koutecký, Jan Kučera, Samah Mohamed Rizk, Rosa M Ros
PREMISE OF THE STUDY: A period of allopatry is widely believed to be essential for the evolution of reproductive isolation. However, strict allopatry may be difficult to achieve in some cosmopolitan, spore-dispersed groups, like mosses. We examined the genetic and genome size diversity in Mediterranean populations of the moss Ceratodon purpureus s.l. to evaluate the role of allopatry and ploidy change in population divergence. METHODS: We sampled populations of the genus Ceratodon from mountainous areas and lowlands of the Mediterranean region, and from Western and Central Europe...
June 29, 2018: American Journal of Botany
Michael J Wise
PREMISE OF THE STUDY: Despite the fact that herbivores can be highly detrimental to their host plants' fitness, plant populations often maintain genetic variation for resistance to their natural enemies. Investigating the various costs (e.g., allocation tradeoffs, autotoxicity, and ecological costs) that may prevent plants from evolving to their fullest potential resistance has been a productive strategy for shedding insight into the eco-evolutionary dynamics of plant-herbivore communities...
June 24, 2018: American Journal of Botany
Guoyan Wang, Carol C Baskin, Jerry M Baskin, Xuejun Yang, Guofang Liu, Xuehua Ye, Xinshi Zhang, Zhenying Huang
PREMISE OF THE STUDY: Much research has focused on plant responses to ongoing climate change, but there is relatively little information about how climate change will affect the early plant life history stages. Understanding how global warming and changes in winter snow pattern will affect seed germination and seedling establishment is crucial for predicting future alpine population and vegetation dynamics. METHODS: In a 2-year study, we tested how warming and alteration in the snowmelt regime, both in isolation and combination, influence seedling emergence phenology, first-year growth, biomass allocation, and survival of four native alpine perennial herbs on the southeastern Tibetan Plateau...
June 21, 2018: American Journal of Botany
Gaurav D Moghe, Lars H Kruse
No abstract text is available yet for this article.
June 20, 2018: American Journal of Botany
L R Rivkin, Spencer C H Barrett, Marc T J Johnson
PREMISE OF THE STUDY: The strength of plant-herbivore interactions varies in space and time, but the factors that explain this variation are poorly understood. Several lines of research suggest that variation in plant reproductive systems and latitude may explain resistance against herbivores, but how these factors jointly affect plant-herbivore interactions has not been investigated in detail. We examined the effects of latitude, sexual system, and plant gender on herbivory in Sagittaria latifolia, an aquatic plant in which populations are typically monoecious (separate female and male flowers) or dioecious (separate female and male plants)...
June 19, 2018: American Journal of Botany
Maria A Gandolfo, Kevin C Nixon, William L Crepet, David A Grimaldi
PREMISE OF THE STUDY: An inflorescence with three pistillate flowers in amber from the early Upper Cretaceous (Turonian, ~90-94 million years ago) of central New Jersey represents the oldest known flowers with features present in an early stem complex of the Fagales. The inflorescence has characteristics of Nothofagaceae, but also has strikingly distinct characters that suggest it is intermediate between Nothofagus and other Fagales. This intermediacy is consistent with its northern hemisphere distribution...
June 14, 2018: American Journal of Botany
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