A Molecular Biogeographic Analysis of the Relationship between North American Melanoploid Grasshoppers and Their Eurasian and South American Relatives

2001 ◽  
Vol 18 (3) ◽  
pp. 460-466 ◽  
Author(s):  
W. Chapco ◽  
G. Litzenberger ◽  
W.R. Kuperus
Keyword(s):  
North American ◽  
South American ◽  
The Relationship ◽  
Biogeographic Analysis

A morphometric evaluation of the subspecies of Fragaria chiloensis

1998 ◽  
Vol 76 (2) ◽  
pp. 290-297 ◽  
Author(s):  
Paul M Catling ◽  
Sue Porebski
Keyword(s):  
Discriminant Analysis ◽  
South America ◽  
North American ◽  
The Other ◽  
South American ◽  
Taxonomic Rank ◽  
Fragaria Chiloensis ◽  
America South ◽  
The Relationship ◽  
Morphometric Evaluation

To evaluate the relationship between the four subspecies of Fragaria chiloensis, 14 characters were measured in 95 plants. F ratios from ANOVA were used to determine and apply the optimal characters for subspecies separation. Discriminant analysis indicated that the Hawaiian ssp. sandwicensis was entirely distinct, differing from the other subspecies in having longer leaflets and longer hairs on the undersurface of the leaflets and more numerous leaflet veins. The South American and North American plants were significantly different but overlapped to a degree. The former differed primarily by having mostly 6-10 petals, instead of having 5-6 (rarely 7) petals. The two North American subspecies overlapped extensively and may be best transferred to a lower taxonomic rank. A key to the subspecies is included.Key words: Fragaria chiloensis, ssp. pacifica, ssp. lucida, ssp.sandwicensis, ssp. chiloensis, Rosaceae, strawberry, taxonomy, classification, morphology, North America, South America, Hawaii.

Diversification of the North American Doellingeria-Eucephalus Clade (Astereae: Asteraceae) Inferred from Molecular and Morphological Evidence

2019 ◽  
Vol 44 (4) ◽  
pp. 930-942
Author(s):  
Geraldine A. Allen ◽  
Luc Brouillet ◽  
John C. Semple ◽  
Heidi J. Guest ◽  
Robert Underhill
Keyword(s):  
North American ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Sister Group ◽  
Morphological Evidence ◽  
South American ◽  
New Combinations ◽  
The North ◽  
Hybridization Event ◽  
Ancient Hybridization

Abstract—Doellingeria and Eucephalus form the earliest-diverging clade of the North American Astereae lineage. Phylogenetic analyses of both nuclear and plastid sequence data show that the Doellingeria-Eucephalus clade consists of two main subclades that differ from current circumscriptions of the two genera. Doellingeria is the sister group to E. elegans, and the Doellingeria + E. elegans subclade in turn is sister to the subclade containing all remaining species of Eucephalus. In the plastid phylogeny, the two subclades are deeply divergent, a pattern that is consistent with an ancient hybridization event involving ancestral species of the Doellingeria-Eucephalus clade and an ancestral taxon of a related North American or South American group. Divergence of the two Doellingeria-Eucephalus subclades may have occurred in association with northward migration from South American ancestors. We combine these two genera under the older of the two names, Doellingeria, and propose 12 new combinations (10 species and two varieties) for all species of Eucephalus.

scholarly journals A Risk-Based Approach to Assess the Operational Resilience of Transmission Grids

2020 ◽  
Vol 10 (14) ◽  
pp. 4761
Author(s):  
Milorad Papic ◽  
Svetlana Ekisheva ◽  
Eduardo Cotilla-Sanchez
Keyword(s):  
Power System ◽  
North American ◽  
Response Times ◽  
Transmission System ◽  
Energy Delivery ◽  
The North ◽  
System Components ◽  
Bulk Power ◽  
Definition Of ◽  
The Relationship

Modern risk analysis studies of the power system increasingly rely on big datasets, either synthesized, simulated, or real utility data. Particularly in the transmission system, outage events have a strong influence on the reliability, resilience, and security of the overall energy delivery infrastructure. In this paper we analyze historical outage data for transmission system components and discuss the implications of nearby overlapping outages with respect to resilience of the power system. We carry out a risk-based assessment using North American Electric Reliability Corporation (NERC) Transmission Availability Data System (TADS) for the North American bulk power system (BPS). We found that the quantification of nearby unscheduled outage clusters would improve the response times for operators to readjust the system and provide better resilience still under the standard definition of N-1 security. Finally, we propose future steps to investigate the relationship between clusters of outages and their electrical proximity, in order to improve operator actions in the operation horizon.

Introduced North American Black Henbane (Hyoscyamus niger) Populations are Biennial

2014 ◽  
Vol 7 (4) ◽  
pp. 624-630 ◽  
Author(s):  
Christa E. Fettig ◽  
Ruth A. Hufbauer
Keyword(s):  
North American ◽  
Common Garden ◽  
Hyoscyamus Niger ◽  
Active Growth ◽  
Black Henbane ◽  
Introduced Populations ◽  
Winter Temperatures ◽  
American Black ◽  
The Relationship ◽  
Bolting And Flowering

AbstractBlack henbane can be either annual or biennial. We investigated which life cycle is found in four introduced western North American populations. Plants were grown in a greenhouse common garden until half were vernalized by exposure to natural winter temperatures, while the other half remained in the greenhouse above 20 C, with 16 h of light and 8 h of dark. In total the plants were monitored 313 d after germination. We measured whether plants bolted, the time it took for bolting to commence, and the size at bolting. All vernalized plants bolted after 117 d of active growth (within 26 d of the end of the vernalization treatment), whereas only 26% of the nonvernalized plants bolted after an average of 278 d of active growth. Vernalized plants bolted at a smaller size than the nonvernalized plants that bolted (28 vs. 41 leaves on average). In the nonvernalized plants, the relationship between time to bolting and size was strong, but not so with the vernalized plants. Our results indicate that introduced black henbane plants are biennial, and that vernalization is more critical to bolting and flowering than reaching a certain size. Nonetheless, the fact that nonvernalized plants were capable of bolting if grown long enough suggests that vernalization is not the only cue that can trigger reproduction in introduced populations.

scholarly journals The effects of geographic range size and abundance on extinction during a time of “sluggish”’ evolution

Paleobiology ◽  
2020 ◽  
pp. 1-14
Author(s):  
Michelle M. Casey ◽  
Erin E. Saupe ◽  
Bruce S. Lieberman
Keyword(s):  
North American ◽  
Fossil Record ◽  
Extinction Risk ◽  
Geographic Range ◽  
Range Size ◽  
Late Paleozoic ◽  
The North ◽  
Geographic Range Size ◽  
The Relationship ◽  
Habitat Tracking

Abstract Geographic range size and abundance are important determinants of extinction risk in fossil and extant taxa. However, the relationship between these variables and extinction risk has not been tested extensively during evolutionarily “quiescent” times of low extinction and speciation in the fossil record. Here we examine the influence of geographic range size and abundance on extinction risk during the late Paleozoic (Mississippian–Permian), a time of “sluggish” evolution when global rates of origination and extinction were roughly half those of other Paleozoic intervals. Analyses used spatiotemporal occurrences for 164 brachiopod species from the North American midcontinent. We found abundance to be a better predictor of extinction risk than measures of geographic range size. Moreover, species exhibited reductions in abundance before their extinction but did not display contractions in geographic range size. The weak relationship between geographic range size and extinction in this time and place may reflect the relative preponderance of larger-ranged taxa combined with the physiographic conditions of the region that allowed for easy habitat tracking that dampened both extinction and speciation. These conditions led to a prolonged period (19–25 Myr) during which standard macroevolutionary rules did not apply.

The relationship between forelimb morphology and behaviour in North American carnivores (Carnivora)

1999 ◽  
Vol 77 (7) ◽  
pp. 1064-1074 ◽  
Author(s):  
Andrew N Iwaniuk ◽  
Sergio M Pellis ◽  
Ian Q Whishaw
Keyword(s):  
North American ◽  
Significant Relationship ◽  
Feeding Behaviour ◽  
Prey Capture ◽  
Relative Size ◽  
Independent Contrasts ◽  
Important Indicator ◽  
Predatory Behaviour ◽  
Olecranon Process ◽  
The Relationship

We tested the validity of previously described relationships between forelimb structure and behaviour in mammals by measuring the forelimbs of 22 species of North American carnivores. Nine ratios were calculated from these measurements and made independent of the effects of allometry and phylogeny through the use of log-transformed regressions and independent contrasts analysis. The ratios were then directly compared with two behavioural traits: arboreal locomotion and vertebrate predation. Only five of the nine ratios exhibited a significant relationship with arboreal locomotion and three with vertebrate predation. It was concluded that the brachial index, relative size of the olecranon process, and total forelimb robusticity may be reliable predictors of arboreal locomotion, and that the brachial index, relative size of the olecranon process, and radial robusticity may be accurate predictors of vertebrate predation. The data also suggest that the morphology of the lower forelimb may be an important indicator of prey-capture and feeding behaviour in carnivores and could be used in conjunction with craniodental variables to extrapolate predatory behaviour of extinct species.

Wilhelm Von Humboldt and North American Ethnolinguistics

1990 ◽  
Vol 17 (1-2) ◽  
pp. 111-128 ◽  
Author(s):  
E. F. Konrad Koerner
Keyword(s):  
North America ◽  
North American ◽  
Philosophy Of Language ◽  
Wilhelm Von Humboldt ◽  
Franz Boas ◽  
Language And Culture ◽  
Language Structure ◽  
The 1960S ◽  
General Linguistics ◽  
The Relationship

Summary Noam Chomsky’s frequent references to the work of Wilhelm von Humboldt during the 1960s produced a considerable revival of interest in this 19th-century scholar in North America. This paper demonstrates that there has been a long-standing influence of Humboldt’s ideas on American linguistics and that no ‘rediscovery’ was required. Although Humboldt’s first contacts with North-American scholars goes back to 1803, the present paper is confined to the posthumous phase of his influence which begins with the work of Heymann Steinthal (1823–1899) from about 1850 onwards. This was also a time when many young Americans went to Germany to complete their education; for instance William Dwight Whitney (1827–1894) spent several years at the universities of Tübingen and Berlin (1850–1854), and in his writings on general linguistics one can trace Humboldtian ideas. In 1885 Daniel G. Brinton (1837–1899) published an English translation of a manuscript by Humboldt on the structure of the verb in Amerindian languages. A year later Franz Boas (1858–1942) arrived from Berlin soon to establish himself as the foremost anthropologist with a strong interest in native language and culture. From then on we encounter Humboldtian ideas in the work of a number of North American anthropological linguists, most notably in the work of Edward Sapir (1884–1939). This is not only true with regard to matters of language classification and typology but also with regard to the philosophy of language, specifically, the relationship between a particular language structure and the kind of thinking it reflects or determines on the part of its speakers. Humboldtian ideas of ‘linguistic relativity’, enunciated in the writings of Whitney, Brinton, Boas, and others, were subsequently developed further by Sapir’s student Benjamin Lee Whorf (1897–1941). The transmission of the so-called Sapir-Whorf Hypothesis – which still today is attracting interest among cultural anthropologists and social psychologists, not only in North America – is the focus of the remainder of the paper. A general Humboldtian approach to language and culture, it is argued, is still present in the work of Dell Hymes and several of his students.

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