Ecogeography and the Great American Interchange

Paleobiology ◽  
1991 ◽  
Vol 17 (3) ◽  
pp. 266-280 ◽  
Author(s):  
S. David Webb
Keyword(s):  
North America ◽  
South America ◽  
North American ◽  
Mammalian Fauna ◽  
The South ◽  
Land Bridge ◽  
Southern Mexico ◽  
The North ◽  
Land Mammal ◽  
The Impact

When the isthmian land bridge triggered the Great American Interchange, a large majority of land-mammal families crossed reciprocally between North and South America at about 2.5 Ma (i.e., Late Pliocene). Initially land-mammal dynamics proceeded as predicted by equilibrium theory, with roughly equal reciprocal mingling on both continents. Also as predicted, the impact of the interchange faded in North America after about 1 m.y. In South America, contrary to such predictions, the interchange became decidedly unbalanced: during the Pleistocene, groups of North American origin continued to diversify at exponential rates. Whereas only about 10% of North American genera are derived from southern immigrants, more than half of the modern mammalian fauna of South America, measured at the generic level, stems from northern immigrants. In addition, extinctions more severely decimated interchange taxa in North America, where six families were lost, than in South America, where only two immigrant families became extinct.This paper presents a two-phase ecogeographic model to explain the asymmetrical results of the land-mammal interchange. During the humid interglacial phase, the tropics were dominated by rain forests, and the principal biotic movement was from Amazonia to Central America and southern Mexico. During the more arid glacial phase, savanna habitats extended broadly right through tropical latitudes. Because the source area in the temperate north was six times as large as that in the south, immigrants from the north outnumbered those from the south. One prediction of this hypothesis is that immigrants from the north generally should reach higher latitudes in South America than the opposing contingent of land-mammal taxa in North America. Another prediction is that successful interchange families from the north should experience much of their phylogenetic diversification in low latitudes of North America before the interchange. Insofar as these predictions can be tested, they appear to be upheld.

scholarly journals Novel Highly Pathogenic Avian A(H5N2) and A(H5N8) Influenza Viruses of Clade 2.3.4.4 from North America Have Limited Capacity for Replication and Transmission in Mammals

mSphere ◽  
2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Bryan S. Kaplan ◽  
Marion Russier ◽  
Trushar Jeevan ◽  
Bindumadhav Marathe ◽  
Elena A. Govorkova ◽  
...  
Keyword(s):  
North America ◽  
Avian Influenza ◽  
North American ◽  
Influenza Viruses ◽  
Morbidity And Mortality ◽  
Avian Influenza Viruses ◽  
Highly Pathogenic ◽  
The North ◽  
Domestic Poultry ◽  
The Impact

ABSTRACT Highly pathogenic H5 influenza viruses have been introduced into North America from Asia, causing extensive morbidity and mortality in domestic poultry. The introduced viruses have reassorted with North American avian influenza viruses, generating viral genotypes not seen on other continents. The experiments and analyses presented here were designed to assess the impact of this genetic diversification on viral phenotypes, particularly as regards mammalian hosts, by comparing the North American viruses with their Eurasian precursor viruses. Highly pathogenic influenza A(H5N8) viruses from clade 2.3.4.4 were introduced to North America by migratory birds in the fall of 2014. Reassortment of A(H5N8) viruses with avian viruses of North American lineage resulted in the generation of novel A(H5N2) viruses with novel genotypes. Through sequencing of recent avian influenza viruses, we identified PB1 and NP gene segments very similar to those in the viruses isolated from North American waterfowl prior to the introduction of A(H5N8) to North America, highlighting these bird species in the origin of reassortant A(H5N2) viruses. While they were highly virulent and transmissible in poultry, we found A(H5N2) viruses to be low pathogenic in mice and ferrets, and replication was limited in both hosts compared with those of recent highly pathogenic avian influenza (HPAI) H5N1 viruses. Molecular characterization of the hemagglutinin protein from A(H5N2) viruses showed that the receptor binding preference, cleavage, and pH of activation were highly adapted for replication in avian species and similar to those of other 2.3.4.4 viruses. In addition, North American and Eurasian clade 2.3.4.4 H5NX viruses replicated to significantly lower titers in differentiated normal human bronchial epithelial cells than did seasonal human A(H1N1) and highly pathogenic A(H5N1) viruses isolated from a human case. Thus, despite their having a high impact on poultry, our findings suggest that the recently emerging North American A(H5N2) viruses are not expected to pose a substantial threat to humans and other mammals without further reassortment and/or adaptation and that reassortment with North American viruses has not had a major impact on viral phenotype. IMPORTANCE Highly pathogenic H5 influenza viruses have been introduced into North America from Asia, causing extensive morbidity and mortality in domestic poultry. The introduced viruses have reassorted with North American avian influenza viruses, generating viral genotypes not seen on other continents. The experiments and analyses presented here were designed to assess the impact of this genetic diversification on viral phenotypes, particularly as regards mammalian hosts, by comparing the North American viruses with their Eurasian precursor viruses.

scholarly journals The Impact of Large-Scale Orography on Northern Hemisphere Winter Synoptic Temperature Variability

2019 ◽  
Vol 32 (18) ◽  
pp. 5799-5814 ◽  
Author(s):  
Nicholas J. Lutsko ◽  
Jane Wilson Baldwin ◽  
Timothy W. Cronin
Keyword(s):  
North America ◽  
Northern Hemisphere ◽  
North American ◽  
Large Scale ◽  
Temperature Variability ◽  
Temperature Gradients ◽  
Northwest Pacific ◽  
Near Surface ◽  
The North ◽  
The Impact

Abstract The impact of large-scale orography on wintertime near-surface (850 hPa) temperature variability on daily and synoptic time scales (from days to weeks) in the Northern Hemisphere is investigated. Using a combination of theory, idealized modeling work, and simulations with a comprehensive climate model, it is shown that large-scale orography reduces upstream temperature gradients, in turn reducing upstream temperature variability, and enhances downstream temperature gradients, enhancing downstream temperature variability. Hence, the presence of the Rockies on the western edge of the North American continent increases temperature gradients over North America and, consequently, increases North American temperature variability. By contrast, the presence of the Tibetan Plateau and the Himalayas on the eastern edge of the Eurasian continent damps temperature variability over most of Eurasia. However, Tibet and the Himalayas also interfere with the downstream development of storms in the North Pacific storm track, and thus damp temperature variability over North America, by approximately as much as the Rockies enhance it. Large-scale orography is also shown to impact the skewness of downstream temperature distributions, as temperatures to the north of the enhanced temperature gradients are more positively skewed while temperatures to the south are more negatively skewed. This effect is most clearly seen in the northwest Pacific, off the east coast of Japan.

scholarly journals THE NORTH AMERICAN SPECIES OF NEMISTRINIDÆ

1883 ◽  
Vol 15 (4) ◽  
pp. 69-72 ◽  
Author(s):  
S. W. Williston
Keyword(s):  
North America ◽  
South America ◽  
North American ◽  
North American Species ◽  
Southern Europe ◽  
The North ◽  
The Family ◽  
The World ◽  
General Appearance

The family of Nemistrinidæ comprises throughout the world one hundred and ten described species, six or seven of which are from Southern Europe and three from North America; the remainder nearly equally distributed in Asia, Africa, Australia and South America. In their habits, so far as known, the species approach the Bombylidæ most closely, as also do many in their general appearance. Structurally they are of interest to the Dipterologist, on account of their intricate and diverse neuration, which in some species is almost Neuropter-like in the reticulation.Doubtless the number of our species will be augmented by future discoveries, but yet we can never expect a very material increase.

scholarly journals Case studies of ozone transport between North America and Europe in summer 2000

2005 ◽  
Vol 5 (4) ◽  
pp. 6127-6184 ◽  
Author(s):  
G. Guerova ◽  
I. Bey ◽  
J.-L. Attié ◽  
R. V. Martin
Keyword(s):  
North America ◽  
North American ◽  
North Atlantic Ocean ◽  
Conveyor Belt ◽  
Tropospheric Chemistry ◽  
Pollution Transport ◽  
The North ◽  
Range Transport ◽  
European Mountain ◽  
The Impact

Abstract. This paper reports on Long Range Transport (LRT) of ozone and related species over the North Atlantic ocean and its impact on Europe. Measurements of NO2 and O3 columns from the GOME and MOPITT satellite instruments are first used in conjunction with the GEOS-CHEM global model of transport and tropospheric chemistry to identify the major events of LRT that reach Europe over the course of the summer 2000. Model simulations are then used to examine surface O3 observations at a European mountain site and O3 vertical profiles over several European cities to quantify the impact of the LRT events on the European ozone distributions. Over the course of summer 2000, we identified nine major episodes of pollution transport between North America and Europe, which are in majority associated with WCB/post-frontal outflow (7 events) and zonal transport (2 events). We find that on average three episodes occur per month with the strongest ones being in June. The number and frequency of LRT events that reach Europe after leaving North America is strongly driven by the position and strength of the Azores anticyclone. After leaving North America, the plumes can either i) travel in the North American cyclones, mostly in the Warm Conveyor Belt (WCB), tracking poleward and thus reach Europe at high latitudes; ii) be transported zonally between 40° and 55° N directly to Europe; iii) be incorporated into the Azores anticyclone and reach Europe at mid-latitudes. Based on model sensitivity simulation it can be concluded that on average the North American sources of ozone contribute between 2–8 ppb in PBL and 10–13 ppb in FT. During particular episodes the North American sources resulted in O3 enhancement up to 25–28 ppb in the layer between 800–600 hPa and 10–12 ppb in PBL. For some episodes a substantial North American contribution (30% or higher) does not translate into a well marked enhancement of the total O3.

THE POST-GLACIAL COLONIZATION OF THE NORTH ATLANTIC ISLANDS

1988 ◽  
Vol 120 (S144) ◽  
pp. 55-92 ◽  
Author(s):  
J.A. Downes
Keyword(s):  
North America ◽  
North Atlantic ◽  
North American ◽  
High Arctic ◽  
The Arctic ◽  
Land Bridge ◽  
The North ◽  
The North Atlantic ◽  
North Greenland ◽  
Arctic Fauna

AbstractThe paper discusses the nature and origins of the present-day insect faunas of Greenland, Iceland, and the Faeroes in relation to those of North America and Europe. The markedly warm-adapted faunas of the Early Tertiary were modified or eliminated as the climate cooled from the Oligocene onward to the Pleistocene glaciations. The Wisconsinan glaciation peaked about 20 000 years ago, and then gave way rapidly to the arctic and cool temperate climates of the present, and the North Atlantic islands thus became habitable again but separated by wide expanses of northern seas. At most only a few strongly arctic-adapted species could have persisted through the Pleistocene and no land bridges from the continents have existed since the Early Miocene, 20 million years ago.Southern Greenland, Iceland, and the Faeroes have been colonized across sea passages from the adjacent continents, mainly by air but partly by sea, during the postglacial period (ca. 10 000 years). The faunas are all young, with no endemic species among about 2000 in all; the faunas are not arctic but distinctly subarctic, mainly of the High and Low Boreal life zones, and derived from these life zones of North America or Europe. The naturally established faunas are small or very small, less than 14% of the corresponding continental faunas, and are obviously disharmonic, with some groups absent across the North Atlantic, e.g. Culicidae, Tabanidae, Tachinidae, Papilionoidea, aculeate Hymenoptera (except Bombus sp.). This indicates a severe "sweepstakes" route. The lack of Tachinidae is noteworthy because their hosts are plentiful, and indicates dispersal by air, with adult Tachinidae, unlike adult Lepidoptera, unable to make the journey; dispersal by a land bridge would offer parasites and hosts an equal opportunity. Aerial transport is indicated also by the high proportion of migrant species (of Lepidoptera) in the island faunas, and the arrival in Surtsey (a new volcanic island) of almost 25% of the Icelandic fauna in 12 years. The Surtsey observations suggest that the Icelandic fauna is preadapted to aerial dispersal, by selection during its journey from Europe.The fauna of southern Greenland is derived partly from boreal America and partly from boreal Europe. The North American moiety becomes vestigial in Iceland and the Faeroes and does not reach Europe. Iceland and the Faeroes have been populated from northwestern Europe, especially Britain and Scandinavia. A few species extend to southern Greenland and thence, or even directly, reach North America, and have thus completed a post-glacial traverse of the North Atlantic.The fauna of North Greenland differs fundamentally from all the above. It is a high arctic fauna, nearly identical with the high arctic fauna in Canada, and thus complete, not disharmonie, though very small by virtue of its high arctic nature. It has encountered no "sweepstakes" dispersal. North Greenland is separated from High Arctic Canada only by a narrow channel which permits winter dispersal by wind across unbroken sea ice. Biologically, North Greenland is part of the North American High Arctic, and although certain species (e.g. mosquitoes and butterflies) may extend somewhat into southern Greenland, it has not contributed to the basic faunas of the North Atlantic islands.Among other problems, the extreme variability in wing pattern of many Lepidoptera in Iceland, the Faeroes, and Shetland is also commented on.

scholarly journals An Updated Infrageneric Classification of the North American Oaks (Quercus Subgenus Quercus): Review of the Contribution of Phylogenomic Data to Biogeography and Species Diversity

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 786
Author(s):  
Paul S. Manos ◽  
Andrew L. Hipp
Keyword(s):  
North America ◽  
North American ◽  
Sister Group ◽  
Regional Patterns ◽  
Infrageneric Classification ◽  
Biogeographic Patterns ◽  
The North ◽  
Species Complexes ◽  
The Impact

The oak flora of North America north of Mexico is both phylogenetically diverse and species-rich, including 92 species placed in five sections of subgenus Quercus, the oak clade centered on the Americas. Despite phylogenetic and taxonomic progress on the genus over the past 45 years, classification of species at the subsectional level remains unchanged since the early treatments by WL Trelease, AA Camus, and CH Muller. In recent work, we used a RAD-seq based phylogeny including 250 species sampled from throughout the Americas and Eurasia to reconstruct the timing and biogeography of the North American oak radiation. This work demonstrates that the North American oak flora comprises mostly regional species radiations with limited phylogenetic affinities to Mexican clades, and two sister group connections to Eurasia. Using this framework, we describe the regional patterns of oak diversity within North America and formally classify 62 species into nine major North American subsections within sections Lobatae (the red oaks) and Quercus (the white oaks), the two largest sections of subgenus Quercus. We also distill emerging evolutionary and biogeographic patterns based on the impact of phylogenomic data on the systematics of multiple species complexes and instances of hybridization.

Staurothele nemorum sp. nov. (Ascomycota: Verrucariaceae), with a revised key to North American Staurothele s. lat.

2019 ◽  
Vol 51 (6) ◽  
pp. 495-506 ◽  
Author(s):  
Caleb A. MORSE ◽  
Douglas LADD
Keyword(s):  
North America ◽  
Great Plains ◽  
North American ◽  
The South ◽  
Southern Great Plains ◽  
The North ◽  
Western Great Plains

AbstractStaurothele nemorum is described as new to science from the southern Great Plains of central North America. The species is characterized by a thin, areolate, epilithic thallus, sessile perithecia, globose to oblong hymenial algal cells and 8-spored asci. Staurothele hymenogonia is restored to the North American flora, based on material from the south-western Great Plains. An updated key to North American members of Staurothele s. lat. is provided.

Fray Alonso De La Vera Cruz and the Beginnings of Philosophic Speculation in the Americas

1944 ◽  
Vol 1 (2) ◽  
pp. 207-214
Author(s):  
Kurt F. Reinhardt
Keyword(s):  
North America ◽  
South America ◽  
North American ◽  
Colleges And Universities ◽  
Vital Function ◽  
Harvard College ◽  
American Reader ◽  
The North ◽  
Philosophic Tradition

The perusal of some of the more recent publications in the field of philosophy that have come out of Mexico and South America, such as the works of Oswaldo Robles and P. Derisi, forces upon the North American reader the realization that the European philosophic tradition in the form of the philosophia perennis was firmly established on this continent several centuries before philosophy began to fulfill its vital function in the curricula of the colleges and universities of North America or, more exactly, 235 years before William Brattle offered the first course in philosophy at Harvard College.

Nachhaltigkeit im Wald – vor und hinter der Welle der Globalisierung | Sustainable Forest Management – In Front and Behind the Wave of Globalization

2000 ◽  
Vol 151 (12) ◽  
pp. 502-507
Author(s):  
Christian Küchli
Keyword(s):  
Forest Management ◽  
Cultural Landscape ◽  
Sustainable Forest Management ◽  
Essential Element ◽  
Specific Situation ◽  
The South ◽  
The North ◽  
Time Space ◽  
Starting Point ◽  
The Impact

Are there any common patterns in the transition processes from traditional and more or less sustainable forest management to exploitative use, which can regularly be observed both in central Europe and in the countries of the South (e.g. India or Indonesia)? Attempts were made with a time-space-model to typify those force fields, in which traditional sustainable forest management is undermined and is then transformed into a modern type of sustainable forest management. Although it is unlikely that the history of the North will become the future of the South, the glimpse into the northern past offers a useful starting point for the understanding of the current situation in the South, which in turn could stimulate the debate on development. For instance, the patterns which stand behind the conflicts on forest use in the Himalayas are very similar to the conflicts in the Alps. In the same way, the impact of socio-economic changes on the environment – key word ‹globalisation› – is often much the same. To recognize comparable patterns can be very valuable because it can act as a stimulant for the search of political, legal and technical solutions adapted to a specific situation. For the global community the realization of the way political-economic alliances work at the head of the ‹globalisationwave›can only signify to carry on trying to find a common language and understanding at the negotiation tables. On the lee side of the destructive breaker it is necessary to conserve and care for what survived. As it was the case in Switzerland these forest islands could once become the germination points for the genesis of a cultural landscape, where close-to-nature managed forests will constitute an essential element.

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