scholarly journals Improving phylogenetic resolution of the Lamiales using the complete plastome sequences of six Penstemon species

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261143
Author(s):  
Jason M. Stettler ◽  
Mikel R. Stevens ◽  
Lindsey M. Meservey ◽  
W. Wesley Crump ◽  
Jed D. Grow ◽  
...  
Keyword(s):  
North American ◽  
Central American ◽  
The Arctic ◽  
Temperate Grasslands ◽  
Individual Gene ◽  
The North ◽  
Phylogenetic Studies ◽  
Plastid Genomes ◽  
Evolutionary Radiation ◽  
Phylogenetic Resolution

The North American endemic genus Penstemon (Mitchell) has a recent geologic origin of ca. 3.6 million years ago (MYA) during the Pliocene/Pleistocene transition and has undergone a rapid adaptive evolutionary radiation with ca. 285 species of perennial forbs and sub-shrubs. Penstemon is divided into six subgenera occupying all North American habitats including the Arctic tundra, Central American tropical forests, alpine meadows, arid deserts, and temperate grasslands. Due to the rapid rate of diversification and speciation, previous phylogenetic studies using individual and concatenated chloroplast sequences have failed to resolve many polytomic clades. We investigated the efficacy of utilizing the plastid genomes (plastomes) of 29 species in the Lamiales order, including five newly sequenced Penstemon plastomes, for analyzing phylogenetic relationships and resolving problematic clades. We compared whole-plastome based phylogenies to phylogenies based on individual gene sequences (matK, ndhF, psaA, psbA, rbcL, rpoC2, and rps2) and concatenated sequences. We also We found that our whole-plastome based phylogeny had higher nodal support than all other phylogenies, which suggests that it provides greater accuracy in describing the hierarchal relationships among taxa as compared to other methods. We found that the genus Penstemon forms a monophyletic clade sister to, but separate from, the Old World taxa of the Plantaginaceae family included in our study. Our whole-plastome based phylogeny also supports the rearrangement of the Scrophulariaceae family and improves resolution of major clades and genera of the Lamiales.

scholarly journals Carbon cycling in the North American coastal ocean: A synthesis

2018 ◽  
Author(s):  
Katja Fennel ◽  
Simone Alin ◽  
Leticia Barbero ◽  
Wiley Evans ◽  
Timotheé Bourgeois ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
North American ◽  
Inorganic Carbon ◽  
Co2 Flux ◽  
Carbon Fluxes ◽  
Coastal Ocean ◽  
Open Ocean ◽  
The Arctic ◽  
The North ◽  
Anthropogenic Carbon

Abstract. A quantification of carbon fluxes in the coastal ocean and across its boundaries, specifically the air-sea, land-to-coastal-ocean and coastal-to-open-ocean interfaces, is important for assessing the current state and projecting future trends in ocean carbon uptake and coastal ocean acidification, but is currently a missing component of global carbon budgeting. This synthesis reviews recent progress in characterizing these carbon fluxes with focus on the North American coastal ocean. Several observing networks and high-resolution regional models are now available. Recent efforts have focused primarily on quantifying net air-sea exchange of carbon dioxide (CO2). Some studies have estimated other key fluxes, such as the exchange of organic and inorganic carbon between shelves and the open ocean. Available estimates of air-sea CO2 flux, informed by more than a decade of observations, indicate that the North American margins act as a net sink for atmospheric CO2. This net uptake is driven primarily by the high-latitude regions. The estimated magnitude of the net flux is 160 ± 80 Tg C/y for the North American Exclusive Economic Zone, a number that is not well constrained. The increasing concentration of inorganic carbon in coastal and open-ocean waters leads to ocean acidification. As a result conditions favouring dissolution of calcium carbonate occur regularly in subsurface coastal waters in the Arctic, which are naturally prone to low pH, and the North Pacific, where upwelling of deep, carbon-rich waters has intensified and, in combination with the uptake of anthropogenic carbon, leads to low seawater pH and aragonite saturation states during the upwelling season. Expanded monitoring and extension of existing model capabilities are required to provide more reliable coastal carbon budgets, projections of future states of the coastal ocean, and quantification of anthropogenic carbon contributions.

Wood anatomy of Cupressus and its relation to geographical distribution

IAWA Journal ◽  
2016 ◽  
Vol 37 (1) ◽  
pp. 48-68 ◽  
Author(s):  
Elena Román-Jordán ◽  
Luis G. Esteban ◽  
Paloma de Palacios ◽  
Francisco G. Fernández
Keyword(s):  
Wood Anatomy ◽  
Central American ◽  
Western Region ◽  
Eastern Region ◽  
Axial Parenchyma ◽  
Chamaecyparis Nootkatensis ◽  
The North ◽  
Phylogenetic Studies ◽  
Molecular Phylogenetic ◽  
Ray Parenchyma Cells

The wood anatomy of 14 species of Cupressus was studied to determine whether there is a pattern of wood anatomical diversity between the species from the North and Central American (western) region and the Eurasian (eastern) region. Xanthocyparis vietnamensis and Chamaecyparis nootkatensis (syn. Xanthocyparis nootkatensis) were also studied to compare their wood anatomy, given their recent inclusion by some authors in Cupressus. The arrangement of the axial parenchyma, morphology of the transverse end walls of the axial parenchyma, presence of ray tracheids, typology of the end walls of the ray parenchyma cells and ray height support to some extent the division of Cupressus into two large groups: the American group (western region) and the Eurasian group (eastern region), as proposed in molecular phylogenetic studies. The wood anatomy of Chamaecyparis nootkatensis shares the presence of ray tracheids and the same ray typology with American Cupressus, and has the same ray height as Eurasian Cupressus. In contrast, Xanthocyparis vietnamensis shares the absence of ray tracheids and the same ray typology with Eurasian Cupressus, and has the same ray height as American Cupressus.

scholarly journals A time and a place for everything: phylogenetic history and geography as joint predictors of oak plastome phylogeny

Genome ◽  
2017 ◽  
Vol 60 (9) ◽  
pp. 720-732 ◽  
Author(s):  
Kasey K. Pham ◽  
Andrew L. Hipp ◽  
Paul S. Manos ◽  
Richard C. Cronn
Keyword(s):  
Dna Sequences ◽  
North American ◽  
Introgressive Hybridization ◽  
White Oak ◽  
Gene Migration ◽  
The North ◽  
Geographic Structure ◽  
Phylogenetic Studies ◽  
Phylogenetic Informativeness ◽  
Lineage Divergence

Owing to high rates of introgressive hybridization, the plastid genome is poorly suited to fine-scale DNA barcoding and phylogenetic studies of the oak genus (Quercus, Fagaceae). At the tips of the oak plastome phylogeny, recent gene migration and reticulation generally cause topology to reflect geographic structure, while deeper branches reflect lineage divergence. In this study, we quantify the simple and partial effects of geographic proximity and nucleome-inferred phylogenetic history on oak plastome phylogeny at different evolutionary scales. Our study compares pairwise phylogenetic distances based on complete plastome sequences, pairwise phylogenetic distances from nuclear restriction site-associated DNA sequences (RADseq), and pairwise geographic distances for 34 individuals of the white oak clade representing 24 North American and Eurasian species. Within the North American white oak clade alone, phylogenetic history has essentially no effect on plastome variation, while geography explains 11%–21% of plastome phylogenetic variance. However, across multiple continents and clades, phylogeny predicts 30%–41% of plastome variation, geography 3%–41%. Tipwise attenuation of phylogenetic informativeness in the plastome means that in practical terms, plastome data has little use in solving phylogenetic questions, but can still be a useful barcoding or phylogenetic marker for resolving questions among major clades.

The Arctic Institute of North America

Polar Record ◽  
1956 ◽  
Vol 8 (52) ◽  
pp. 22-23 ◽  
Author(s):  
P. D. Baird
Keyword(s):  
North America ◽  
North American ◽  
Scientific Research ◽  
The Arctic ◽  
The North ◽  
Reference Information ◽  
North American Arctic ◽  
Mcgill University

The Arctic Institute of North America was established in 1945 in two small rooms in McGill University, with a staff consisting of Dr Lincoln Washburn and a secretary, who made up for the lack of equipment and facilities by abundant energy and enthusiasm. Since then the Institute's growth has been considerable, always in the direction of its three main objectives—to form a centre for reference information and study on the North American Arctic, to encourage arctic scientific research in any field, and to disseminate arctic information by means of a journal, other publications, and lectures.

scholarly journals Athapaskan migration to the North American Sout

2019 ◽  
Vol 12 ◽  
pp. 139-164
Author(s):  
Magdalena Lewandowska
Keyword(s):  
Great Plains ◽  
North American ◽  
Salt Lake ◽  
American Southwest ◽  
The Arctic ◽  
Migration Route ◽  
Historical Sources ◽  
Subarctic Region ◽  
The North ◽  
Athabaskan Language

The arrival of the ancestors of the Apaches and Navajo to the North American Southwest, the so-called Apachean migra-tion is one of the most widely discussed issues in American archeology. Since the 19th century, after connections were disco-vered between the Athabaskan language family, potential routes and directions of migration between the Arctic and Subarctic region (inhabited by the Northern Athabaskans) and the Southwest (inhabited by the Southern Athabaskans) began to be con-sidered. During the 1930s, the Edward Sapir’s linguistic research made it possible to determine that the migration flowed from north to south, but this conclusion merely sowed the seed of research on Apachean migration, which has since blossomed with archaeological discoveries from the last 20 or 30 years. Today, we are able to pinpoint what prompted the Athabaskans’ journey; we also know of cultures such as Promontory (around the Great Salt Lake) or Dismal River (Great Plains), which we associate with the presence of the Apachean people on both sides of the Rocky Mountains. Still, many questions remain unanswered, and previous hypotheses are being verified in the light of new discoveries. No less interesting proved the results of research into some auxiliary sciences of archeology: genetics and linguistics, and the analysis of historical sources and oral tradition.The following article aims to introduce the reader to the most important and recent discoveries related to the issue of Apachean migration, and present hypotheses that have recently emerged in the scientific community, both in the context of the migration route itself and arrival in the Southwest, as well as the dates associated with them.

scholarly journals The Oxford Handbook of the Prehistoric Arctic

2016 ◽  
Keyword(s):  
North American ◽  
Full Range ◽  
Limited Range ◽  
Great Accuracy ◽  
The Arctic ◽  
Stone Tool ◽  
Cultural Tradition ◽  
Cold Temperatures ◽  
The North ◽  
North American Arctic

The North American Arctic was one of the last regions on Earth to be settled by humans, due to its extreme climate, limited range of resources, and remoteness from populated areas. Despite these factors, it holds a rich and complex history relating to Inuit, Iñupiat, Inuvialuit, Yupik, and Aleut peoples and their ancestors. The artifacts, dwellings, and food remains of these ancient peoples are remarkably well preserved due to cold temperatures and permafrost, allowing archaeologists to reconstruct their lifeways with great accuracy. Furthermore, the combination of modern Elders’ traditional knowledge with the region’s high-resolution ethnographic record allows past peoples’ lives to be reconstructed to a level simply not possible elsewhere. Combined, these factors yield an archaeological record of global significance—the Arctic provides ideal case studies relating to issues as diverse as the impacts of climate change on human societies, the complex process of interaction between indigenous peoples and Europeans, and the dynamic relationships between environment, economy, social organization, and ideology in hunter-gatherer societies. In this book, each Arctic cultural tradition is described in detail, with up-to-date coverage of recent interpretations of all aspects of their lifeways. Additional chapters cover broad themes applicable to the full range of arctic cultures, such as trade, stone tool technology, ancient DNA research, and the relationship between archaeology and modern arctic communities. The resulting volume, written by the region’s leading researchers, is by far the most comprehensive coverage of North American arctic archaeology ever assembled.

scholarly journals Refugial origin and postglacial colonization of holarctic reindeer and caribou

Rangifer ◽  
2005 ◽  
Vol 25 (1) ◽  
pp. 19-30 ◽  
Author(s):  
Knut H. Røed
Keyword(s):  
North American ◽  
Rangifer Tarandus ◽  
Nuclear Dna ◽  
Environmental Changes ◽  
Ice Sheet ◽  
The Arctic ◽  
Gene Pools ◽  
Woodland Caribou ◽  
The North ◽  
Morphological Differences

The classification and colonization of reindeer and caribou (Rangifer tarandus) was assessed from analysis of both proteins, nuclear DNA and mitochondrial DNA. I demonstrate that the current subspecies designations are not compatible with the differentiation at these markers, suggesting that the morphological differences among extant subspecies did not evolve in separate glacial refugia. Thus, morphological differences among extant subspecies probably evolved as adaptive responses to post-glacial environmental changes. An exception to this is the North American woodland caribou, where all three marker systems support a subspecies-specific refugium as the ancestral origin of these animals. Three major mtDNA haplogroups reported, represent three separate origins of the species during the last glaciation. The most influential origin has contributed to the gene pool of all extant subspecies, suggesting the existence of a large and continuous glacial population ranging across extensive areas of tundra in Eurasia and Beringia. The North American tundra forms (R.t. granti and groenlandicus) and the arctic forms (R.t platyrhynchus, R.t pearyi and R.t eogroenlandicus) almost exclusively comprise haplotypes of such an origin. Another small and isolated refugium seems to have arisen in western Eurasia in close connection to the extensive ice sheet that covered Fennoscandia. The two Eurasian subspecies R.t. tarandus and R.t. fennicus appear to have a diphyletic origin as both the putatively small and isolated Eurasian refugium and the large Beringia refugium have contributed to their gene pools. A third distinct and geographically well-defined refugial area was probably located south to the extensive North American continental ice sheet from where the ancestors of the present North American woodland caribou (R.t. caribou) likely originated.Abstract in Norwegian / Sammendrag: Systematisk inndeling og kolonisering av rein (Rangifer tarandus) ble bestemt ved å analysere for variasjon i genetiske markører som proteiner, kjerneDNA og mitokondrieDNA. Dagens oppdeling av rein i underarter viser liten overensstemmelse med variasjonsmønsteret i de undersøkte markørene, noe som viser at de morfologiske forskjellene som karakteriserer dagens underarter ikke har utviklet seg i atskilte refugier i løpet av siste istid. Unntak fra dette er nordamerikansk skogsrein (woodland caribou-R.t. caribou) hvor alle tre markørsystemene indikerer at denne har utviklet seg i et refugium forskjellig fra andre underarter. De tre registrerte hovedhaplogruppene i mitokondrie-DNA representerer tre atskilte opprinnelser av rein i løpet av siste istid. Den mest innflytelsesrike av disse bidro vesentlig til genbanken til alle dagens underarter av rein, noe som tyder på at det under siste istid eksisterte en stor reinpopulasjon med kontinuerlig utbredelse gjennom store deler av tundraen i Eurasia og Beringia. De nordamerikanske tundrareintypene (R.t. granti og R.t. groenlandicus), samt de arktiske typene (R.t. platyrhunchus, R.t. pearyi og R.t. eogroenlandicus) består nærmest utelukkende av haplotyper med denne opprinnelse. Et annet lite og isolert refugium syntes å ha oppstått i Vest-Europa i nærheten av den omfattende isbreen som dekket Fennoskandia. De to europeiske underarter, R.t. tarandus og R.t. fennicus, syntes å ha en todelt opprinnelse med genetisk påvirkning fra både det antatt lille og isolerte refugiet i Eurasia samt fra det store Beringia refugiet. Et tredje geografisk distinkt refugium var antagelig lokalisert sør for den omfattende isbreen i Nord Amerika hvorfra forfedrene til dagens nordamerikanske skogsrein (R.t. caribou) har sin mest sannsynlige opprinnelse.

scholarly journals Timing of Breeding Site Availability Across the North-American Arctic Partly Determines Spring Migration Schedule in a Long-Distance Neotropical Migrant

2021 ◽  
Vol 9 ◽  
Author(s):  
Jean-François Lamarre ◽  
Gilles Gauthier ◽  
Richard B. Lanctot ◽  
Sarah T. Saalfeld ◽  
Oliver P. Love ◽  
...  
Keyword(s):  
North American ◽  
Breeding Site ◽  
The Arctic ◽  
Timing Of Breeding ◽  
Long Distance ◽  
Breeding Sites ◽  
The North ◽  
North American Arctic ◽  
Departure Date ◽  
Breeding Location

Long-distance migrants are under strong selection to arrive on their breeding grounds at a time that maximizes fitness. Many arctic birds start nesting shortly after snow recedes from their breeding sites and timing of snowmelt can vary substantially over the breeding range of widespread species. We tested the hypothesis that migration schedules of individuals co-occurring at the same non-breeding areas are adapted to average local environmental conditions encountered at their specific and distant Arctic breeding locations. We predicted that timing of breeding site availability (measured here as the average snow-free date) should explain individual variation in departure time from shared non-breeding areas. We tested our prediction by tracking American Golden-Plovers (Pluvialis dominica) nesting across the North-American Arctic. These plovers use a non-breeding (wintering) area in South America and share a spring stopover area in the nearctic temperate grasslands, located >1,800 km away from their nesting locations. As plovers co-occur at the same non-breeding areas but use breeding sites segregated by latitude and longitude, we could disentangle the potential confounding effects of migration distance and timing of breeding site availability on individual migration schedule. As predicted, departure date of individuals stopping-over in sympatry was positively related to the average snow-free date at their respective breeding location, which was also related to individual onset of incubation. Departure date from the shared stopover area was not explained by the distance between the stopover and the breeding location, nor by the stopover duration of individuals. This strongly suggests that plover migration schedule is adapted to and driven by the timing of breeding site availability per se. The proximate mechanism underlying the variable migration schedule of individuals is unknown and may result from genetic differences or individual learning. Temperatures are currently changing at different speeds across the Arctic and this likely generates substantial heterogeneity in the strength of selection pressure on migratory schedule of arctic birds migrating sympatrically.

scholarly journals A Benchmark for Trace Greenhouse Gases in the Arctic Ocean

Eos ◽  
2017 ◽  
Author(s):  
Terri Cook
Keyword(s):  
Nitrous Oxide ◽  
Greenhouse Gases ◽  
Arctic Ocean ◽  
North American ◽  
The Arctic ◽  
The North ◽  
The Arctic Ocean ◽  
North American Arctic

Samples of seawater from the North American Arctic show that the region is neither a major source nor sink of methane and nitrous oxide to the overlying atmosphere.

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