scholarly journals A taxonomic evaluation of Astrophytum myriostigma var. Nudum (Cactaceae)

2020 ◽  
Vol 14 (2) ◽  
pp. 255-264
Author(s):  
Richard R. Montanucci ◽  
Klaus-Peter Kleszewski
Keyword(s):  
Solar Radiation ◽  
Morphological Study ◽  
Clinal Variation ◽  
Low Frequencies ◽  
Local Populations ◽  
The North ◽  
San Pedro ◽  
Infraspecific Taxa ◽  
Stem Temperature ◽  
Taxonomic Evaluation

The absence of epidermal trichomes has been used as a diagnostic character to distinguish Astrophytum myriostigma var. nudum from other infraspecific taxa. In the Huizache region of San Luis Potosi, Mexico, between the elevations of 1320 m and 1700 m, the local populations of A. myriostigma are polymorphic, comprised of nude, semi-nude, and flecked plants. However, this polymorphism is non-discrete as there is considerable variation and intermediacy among plants. Also, the proportion of nude plants increases gradually with elevation, which suggests clinal variation correlated with altitude. Exclusively nude populations are currently known only from near Santa Rita del Rucio (? 1710 m) and south of Entronque Huizache (? 1750 m). Farther south, flecked plants were recorded at 1726 m elevation at 6 km E of Guadalcazar, and to the north near El Realejo flecked plants occur as high as 1920 m. At localities southeast of the Sierra San Pedro (Sierra Guadalcazar), nude and semi-nude plants are absent or present at relatively low frequencies in local populations. Epidermal trichomes provide shading and reflectance that protects the cactus stem against excessive solar radiation and moderates stem temperature. The majority of nude A. myriostigma growing in exposed locations at the margins of Hechtia colonies were found to suffer from chlorophyll degeneration due to excessive exposure to solar radiation. A comparative morphological study did not find any characters which can be used in combination to diagnose the var. nudum. Given the lack of a suite of discrete, or nearly discrete diagnostic characters, and given that exclusively nude populations do not have a definable geographic distribution we suggest that the nude phenotype should be treated taxonomically as a “form” rather than as a geographical “variety,” or subspecies. 

DIVERSITY OF CRYPTOGAMIC PLANTS AND FUNGI IN “EVOLUTION CANYON”, NAHAL OREN, MOUNT CARMEL NATURAL PRESERVE, ISRAEL

1995 ◽  
Vol 43 (4) ◽  
pp. 367-383 ◽  
Author(s):  
S.P. Wasser ◽  
E. Nevo ◽  
O.N. Vinogradova ◽  
I.L. Navrotskaya ◽  
I.A. Ellanskaya ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Research Program ◽  
The South ◽  
Valley Bottom ◽  
Lichenicolous Fungi ◽  
The North ◽  
Evolution Canyon ◽  
Infraspecific Taxa

The diversity of cryptogamic plants and fungi has been studied, in the context of a research program of biodiversity across phylogeny, at the “Evolution Canyon” microsite. Lower Nahal Oren, Mount Carmel Natural Preserve, Israel. The opposite slopes of Evolution Canyon display dramatic biotic contrasts due to higher (up to 300%) solar radiation on the south-facing slope (S-slope) which is warmer, drier, and climatically more fluctuating than the north-facing slope (N-slope). Diversity of cryptogamic plants and fungi (198 species and intraspecific taxa) at Evolution Canyon is considerable. The list includes 46 taxa of Cyanophyta, 10 of Chlorophyta, 3 of Euglenophyta, 1 of Bacillariophyta, 29 of lichens, 2 of lichenicolous fungi, 59 of soil micromycetes, 39 of Agaricales s.l., and 9 of mosses. Fifty species and infraspecific taxa are new for the biota of Israel, among them 22 taxa of algae, 9 of micromycetes, 8 of Agaricales s.l., 9 of lichens, and 2 of lichenicolous fungi. Some of them are new for the biota of Asia. While fungi (especially Agaricales s.l.) and mosses primarily range on the more wet and humid “temperate European” N-facing slope, or in the valley bottom (mosses), algae, primarily due to the number of cyanobacteria, predominate on the warm and dry “tropical African” S-facing slope.

scholarly journals Optimal design of the solar tracking system of parabolic trough concentrating collectors

2020 ◽  
Vol 15 (4) ◽  
pp. 613-619
Author(s):  
Li Kong ◽  
Yunpeng Zhang ◽  
Zhijian Lin ◽  
Zhongzhu Qiu ◽  
Chunying Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Radiation ◽  
Tracking System ◽  
Low Cost ◽  
Parabolic Trough ◽  
The North ◽  
Tracking Mode ◽  
Solar Tracking ◽  
East West

Abstract The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking > north-south Earth’s axis tracking > north-south tilt tracking (β = 15°) > north-south tilt tracking (β = 45) > north-south horizontal tracking > east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.

Vegetation Changes around Haven Lake, Adak Island, Central Aleutians, Alaska, Determined from Pollen Analysis

Radiocarbon ◽  
2018 ◽  
Vol 60 (5) ◽  
pp. 1483-1492 ◽  
Author(s):  
Makoto Noguchi ◽  
Toshiyuki Fujiki ◽  
Mitsuru Okuno ◽  
Lyn Gualtieri ◽  
Virginia Hatfield ◽  
...  
Keyword(s):  
Aleutian Islands ◽  
Vegetation Changes ◽  
Sectional Area ◽  
Pollen Assemblage ◽  
Cross Sectional ◽  
Low Frequencies ◽  
The North ◽  
North Side ◽  
Total Cross Sectional Area ◽  
Tephra Layers

ABSTRACTWe collected peat sediments (sediment core ADK13083002) from Haven Lake on the north side of Adak Island (central Aleutian Islands, Alaska) to determine whether the vegetation has changed. We confirmed the presence of six tephra layers, including Forty Years (0.3 cal ka BP), T2, YBO (3.3 cal ka BP), Intermediate (6.4 cal ka BP), Main (9.5 cal ka BP), and T6. We identified four major pollen assemblage zones (HL-1 to HL-4, in descending order) in the cored sediment. HL-1 was dominated by Ranunculaceae and Empetrum pollen; H-2 was dominated by Poaceae, Ranunculaceae, and Empetrum pollen; HL-3 was dominated by Poaceae and Empetrum pollen; and HL-4 was dominated by Poaceae, Cyperaceae, Lycopodiaceae, and Empetrum pollen. Small charcoal particles, likely transported from a distance, were found at low frequencies until 6.4 cal ka BP. The total cross-sectional area of charcoal particles increased to 1500 μm2 or more by 6.4 cal ka BP, implying that the large charcoal particles originated from nearby Aleut settlements, which were established around the same time.

scholarly journals First records of the North American leafhopper Gyponana mail (Hemiptera: Cicadellidae) invading urban gardens and agroecosystems in Europe

2021 ◽  
pp. 213-219
Author(s):  
Valeria Trivellone ◽  
Vally Forte ◽  
Luisa Filippin ◽  
Christopher H. Dietrich
Keyword(s):  
Phylogenetic Analysis ◽  
Host Plant ◽  
North American ◽  
Male Genitalia ◽  
Morphological Study ◽  
European Population ◽  
Northern Italy ◽  
Urban Gardens ◽  
The North ◽  
Palearctic Region

The Nearctic leafhopper species Gyponana (Gyponana) mali DeLong, 1942 is reported from Europe for the fi rst time and represents the fi rst record of the tribe Gyponini Stål, 1870 (Hemiptera: Cicadellidae: Iassinae: Gyponini) for the Palearctic Region. Specimens were collected in southern Switzerland (Ticino) and two regions of northern Italy (Lombardy and Veneto) in 2015–2019. The preferred host plant in these areas appears to be Cornus sanguinea L. Phylogenetic analysis of the COI barcode sequences grouped one of the European specimens with three individuals of G. (G.) mali from Ontario, Canada. Morphological study indicated that the male genitalia of the European population are intermediate between G. (G.) mali and G. (G.) extenda DeLong, 1942.

scholarly journals Arctic East Siberia had a lower latitude in the Pleistocene

2007 ◽  
Vol 79 (2) ◽  
pp. 183-193
Author(s):  
Willy Woelfli ◽  
Walter Baltensperger
Keyword(s):  
Solar Radiation ◽  
Rotation Axis ◽  
Equilibrium Shape ◽  
The Arctic ◽  
Lower Latitude ◽  
Particle Collisions ◽  
East Siberia ◽  
The North ◽  
Massive Object ◽  
Arctic Sea

Remains of mammoths in Arctic East Siberia, where there is not sufficient sunlight over the year for the growth of the plants on which these animals feed, indicate that the latitude of this region was lower before the end of the Pleistocene than now. Reconstructing this geographic pole shift, we introduce a massive object, which moved in an extremely eccentric orbit and was hot from tidal work and solar radiation. Evaporation produced a disk-shaped cloud of ions around the Sun. This cloud partially shielded the solar radiation, producing the cold and warm periods characterizing the Pleistocene. The shielding depends on the inclination of Earth's orbit, which has a period of 100. 000 years. The cloud builds up to a point where inelastic particle collisions induce its collapse The resulting near-periodic time dependence resembles that of Dansgaard-Oeschger events. The Pleistocene ended when the massive object had a close encounter with the Earth, which suffered a one per mil extensional deformation. While the deformation relaxed to an equilibrium shape in one to several years, the globe turned relative to the rotation axis: The North Pole moved from Greenland to the Arctic Sea. The massive object split into fragments, which evaporated.

scholarly journals Aquaculture-driven evolution: distribution of pyrethroid resistance in the salmon louse throughout the North Atlantic in the years 2000–2017

2020 ◽  
Vol 77 (5) ◽  
pp. 1806-1815 ◽  
Author(s):  
Helene Børretzen Fjørtoft ◽  
Frank Nilsen ◽  
Francois Besnier ◽  
Per Gunnar Espedal ◽  
Anne Stene ◽  
...  
Keyword(s):  
North Atlantic ◽  
Pyrethroid Resistance ◽  
Fish Farms ◽  
Low Frequencies ◽  
Salmon Louse ◽  
The North ◽  
The North Atlantic ◽  
Intensive Aquaculture ◽  
Very High Frequencies ◽  
Year 2000

Abstract The parasitic salmon louse, and its documented resistance to chemotherapeutants, represents the most persistent environmental challenge to global salmonid aquaculture. We used a genetic marker associated with pyrethroid resistance to analyse ∼15 000 lice collected from the North Atlantic in the period 2000–2017. The genotype associated with resistance was not detected in lice collected from throughout the North Atlantic in the year 2000 or 2002. However, by the year 2009 onwards, it was found in lice from fish farms throughout much of the North Atlantic. It was also found in modest frequencies in lice collected from wild Atlantic salmon captured off Greenland. The most recent samples displayed very high frequencies of the genotype associated with resistance, particularly in intensive aquaculture regions of Norway (>90%) and Scotland (>70%). These results closely align with observations from the field. We suggest that pyrethroid resistance first emerged in Europe just before or around the year 2000 and was thereafter dispersed throughout much of the North Atlantic where its increased frequency was driven by extensive pyrethroid use. Although the resistant genotype was not detected in lice from Canada, it is likely to occur in very low frequencies that would quickly increase if pyrethroids were to be used in that region.

Improving Climatic Comfort of Citizens by Adjusting the Orientation and Extension of Physics of City Squares: Case Study of Yazd

2017 ◽  
Vol 05 (02) ◽  
pp. 1750012
Author(s):  
Fouad KHEIRABADI ◽  
Hooshmand ALIZADEH ◽  
Hossein NOURMOHAMMADZAD
Keyword(s):  
Solar Radiation ◽  
Correlation Method ◽  
The Body ◽  
Human Beings ◽  
The North ◽  
The Earth ◽  
The City ◽  
High Building ◽  
Software Measures

The heat of the earth is provided by solar radiation. A change in the angle of solar radiation and the surface of the earth causes changes in the ambient temperature. Sometimes, these changes reduce climatic comfort of human beings. Climatic comfort is established when there is a balance between excreted and absorbed temperatures of the skin of the body. Orientation and extension rates of physics of squares relative to the geographical north influence the amount of received direct sunlight in different months. Relevant studies show that the squares of the city of Yazd reduce the climatic comfort of its citizens; moreover, the physics of Yazd's squares apply various extension rates, which led to high building costs to citizens and relevant organizations. This study, by using the correlation method and R software, measures different orientation and extension rates of physics of squares in Yazd. It analyzes two models with orientation and physical extension as variables and evaluates the shade and sunlight in the space. The results reveal significant differences between desirable and undesirable options. Considering the climatic comfort of space users and residents at the same time, a rectangle with an extension ratio of one to several and the north-south orientation, making the lowest facade face the south, is the most appropriate physic for city squares.

Prehistoric Demography in the Southwest: Migration, Coalescence, and Hohokam Population Decline

2004 ◽  
Vol 69 (4) ◽  
pp. 689-716 ◽  
Author(s):  
J. Brett Hill ◽  
Jeffery J. Clark ◽  
William H. Doelle ◽  
Patrick D. Lyons
Keyword(s):  
Population Studies ◽  
Population Decline ◽  
Archaeological Record ◽  
Cultural Traditions ◽  
San Pedro River ◽  
The North ◽  
San Pedro ◽  
Demographic Processes ◽  
Regional Population ◽  
Local Research

One of the most prominent but least understood demographic phenomena in the precontact Southwest is the disappearance of the Hohokam from the valleys of southern Arizona. Despite extensive research, no widely accepted explanation has been offered. We argue that the failure to identify a satisfactory cause is due to excessive focus on catastrophic phenomena and terminal occupations, and a lack of attention to gradual demographic processes. Based on a combination of macro-regional population studies and local research in the lower San Pedro River valley, we present an explanation for gradual population decline precipitated by social and economic coalescence beginning in the late A.D. 1200s. In the southern Southwest an influx of immigrants from the north led to a shift from a dispersed, extensive settlement/subsistence strategy to increased conflict, aggregation, and economic intensification. This shift resulted in diminished health and transformation from population growth to decline. Over approximately 150 years gradual population decline resulted in small remnant groups unable to maintain viable communities. Small, terminal populations were ultimately unable to continue identifiable Hohokam cultural traditions and consequently disappeared from the archaeological record of southern Arizona, either through migration or a shift in lifestyle that rendered them archaeologically invisible.

A revision of the Leptogium saturninum group in North America

2016 ◽  
Vol 48 (5) ◽  
pp. 387-421 ◽  
Author(s):  
Daphne F. STONE ◽  
James W. HINDS ◽  
Frances L. ANDERSON ◽  
James C. LENDEMER
Keyword(s):  
North American ◽  
Morphological Study ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Lower Surface ◽  
Molecular Data ◽  
The North ◽  
Molecular Phylogenetic ◽  
Nrits Sequence

AbstractA revision of the North American members of the Leptogium saturninum group (i.e. species with long lower-surface hairs, isidia, and usually smooth upper surface) is presented based on molecular phylogenetic analyses of mtSSU and nrITS sequence data, together with an extensive morphological study. Three species supported by both molecular and morphological characteristics are recognized: L. acadiense sp. nov. (distinguished by granular saturninum-type isidia, medulla composed of irregularly arranged or perpendicular hyphae), L. cookii sp. nov. (distinguished by cylindrical saturninum-type isidia) and L. hirsutum (distinguished by hirsutum-type isidia and medulla composed of loosely intertwined hyphae). One species supported by morphological characteristics, but for which no molecular data could be generated, is also recognized: L. compactum sp. nov. (distinguished by hirsutum-type isidia and medulla composed of tightly packed hyphae). Finally, L. saturninum (distinguished by granular saturninum-type isidia and medulla composed of perpendicular and parallel hyphae) is supported by morphological characteristics but molecular data from geographically diverse populations, including those near the type locality, indicate that the morphologically defined species is paraphyletic. Leptogium burnetiae is excluded from North American based on morphological study of the type. The species are described and illustrated in detail, and are distinguished morphologically by their isidium development, morphology of mature isidia, and pattern of hyphae in the medulla in transverse sections near lobe margins. A key to the members of the L. saturninum group and related species is also presented.

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