Manfred Görlach
- Published in print:
- 2004
- Published Online:
- January 2010
- ISBN:
- 9780199273102
- eISBN:
- 9780191706271
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199273102.001.0001
- Subject:
- Linguistics, Historical Linguistics, English Language
This book charts the English invasion of Europe since 1945. Sixteen contributors report on the English words and phrases that have become integral parts of their languages. Each describes the effect ...
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This book charts the English invasion of Europe since 1945. Sixteen contributors report on the English words and phrases that have become integral parts of their languages. Each describes the effect of English on the host language, and shows how the process of incorporation often modifies pronunciation and spelling and frequently transforms meaning and use. The languages surveyed are Icelandic, Dutch, French, Spanish, Norwegian, German, Italian, Romanian, Polish, Croatian, Finnish, Albanian, Russian, Bulgarian, Hungarian, and Greek. This book provides a systematic survey of a phenomenon that is fascinating, alarming, and apparently unstoppable.Less
This book charts the English invasion of Europe since 1945. Sixteen contributors report on the English words and phrases that have become integral parts of their languages. Each describes the effect of English on the host language, and shows how the process of incorporation often modifies pronunciation and spelling and frequently transforms meaning and use. The languages surveyed are Icelandic, Dutch, French, Spanish, Norwegian, German, Italian, Romanian, Polish, Croatian, Finnish, Albanian, Russian, Bulgarian, Hungarian, and Greek. This book provides a systematic survey of a phenomenon that is fascinating, alarming, and apparently unstoppable.
Joshua S. Weitz
- Published in print:
- 2016
- Published Online:
- October 2017
- ISBN:
- 9780691161549
- eISBN:
- 9781400873968
- Item type:
- book
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691161549.001.0001
- Subject:
- Biology, Disease Ecology / Epidemiology
When we think about viruses we tend to consider ones that afflict humans—such as those that cause influenza, HIV, and Ebola. Yet, vastly more viruses infect single-celled microbes. Diverse and ...
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When we think about viruses we tend to consider ones that afflict humans—such as those that cause influenza, HIV, and Ebola. Yet, vastly more viruses infect single-celled microbes. Diverse and abundant, microbes and the viruses that infect them are found in oceans, lakes, plants, soil, and animal-associated microbiomes. Taking a vital look at the “microscopic” mode of disease dynamics, this book establishes a theoretical foundation from which to model and predict the ecological and evolutionary dynamics that result from the interaction between viruses and their microbial hosts. The book addresses three major questions: What are viruses of microbes and what do they do to their hosts? How do interactions of a single virus–host pair affect the number and traits of hosts and virus populations? How do virus–host dynamics emerge in natural environments when interactions take place between many viruses and many hosts? Emphasizing how theory and models can provide answers, the book offers a cohesive framework for tackling new challenges in the study of viruses and microbes and how they are connected to ecological processes—from the laboratory to the Earth system. The book is an innovative exploration of the influence of viruses in our complex natural world.Less
When we think about viruses we tend to consider ones that afflict humans—such as those that cause influenza, HIV, and Ebola. Yet, vastly more viruses infect single-celled microbes. Diverse and abundant, microbes and the viruses that infect them are found in oceans, lakes, plants, soil, and animal-associated microbiomes. Taking a vital look at the “microscopic” mode of disease dynamics, this book establishes a theoretical foundation from which to model and predict the ecological and evolutionary dynamics that result from the interaction between viruses and their microbial hosts. The book addresses three major questions: What are viruses of microbes and what do they do to their hosts? How do interactions of a single virus–host pair affect the number and traits of hosts and virus populations? How do virus–host dynamics emerge in natural environments when interactions take place between many viruses and many hosts? Emphasizing how theory and models can provide answers, the book offers a cohesive framework for tackling new challenges in the study of viruses and microbes and how they are connected to ecological processes—from the laboratory to the Earth system. The book is an innovative exploration of the influence of viruses in our complex natural world.
Diana J. Bell, Scott Roberton, and Paul R. Hunter
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198568193
- eISBN:
- 9780191718175
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198568193.003.0009
- Subject:
- Biology, Disease Ecology / Epidemiology
This chapter discusses the search for the wildlife reservoir of SARS-CoV. It starts by presenting the case for extending the search for the zoonotic reservoir in terms of both geographical area and ...
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This chapter discusses the search for the wildlife reservoir of SARS-CoV. It starts by presenting the case for extending the search for the zoonotic reservoir in terms of both geographical area and the range of species investigated. It highlights regional ecological shifts associated with an illegal international wildlife trade and the growing ‘bush-meat’ trade, which simultaneously favours the emergence of new zoonotic infection risks to humans and poses the primary threat to biodiversity across the Indochina Hotspot. The chapter concludes with the presentation of possible solutions to this problem, including interdisciplinary collaboration with vertebrate and conservation biologists with specialist knowledge of potential host species and the wildlife trade.Less
This chapter discusses the search for the wildlife reservoir of SARS-CoV. It starts by presenting the case for extending the search for the zoonotic reservoir in terms of both geographical area and the range of species investigated. It highlights regional ecological shifts associated with an illegal international wildlife trade and the growing ‘bush-meat’ trade, which simultaneously favours the emergence of new zoonotic infection risks to humans and poses the primary threat to biodiversity across the Indochina Hotspot. The chapter concludes with the presentation of possible solutions to this problem, including interdisciplinary collaboration with vertebrate and conservation biologists with specialist knowledge of potential host species and the wildlife trade.
Gil Loescher
- Published in print:
- 2001
- Published Online:
- November 2003
- ISBN:
- 9780199246915
- eISBN:
- 9780191599781
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0199246912.003.0010
- Subject:
- Political Science, International Relations and Politics
A key focus is the organizational culture and effectiveness of UNHCR as the principal protection agency for refugees. UNHCR functions with an imperfect mandate, under circumstances necessitating ...
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A key focus is the organizational culture and effectiveness of UNHCR as the principal protection agency for refugees. UNHCR functions with an imperfect mandate, under circumstances necessitating competition with other agencies for limited resources, and in political environments that are inhospitable to crisis management and refugee protection. Because of its financial vulnerability and dependence on donor governments and host states, the agency's actions are clearly shaped by the interests of governments. The UNHCR finds it difficult to learn from past mistakes and it lacks strong policy research and strategic thinking capacities. The author offers policy recommendations aimed at making UNHCR more effective and accountable in its central function of protecting refugees.Less
A key focus is the organizational culture and effectiveness of UNHCR as the principal protection agency for refugees. UNHCR functions with an imperfect mandate, under circumstances necessitating competition with other agencies for limited resources, and in political environments that are inhospitable to crisis management and refugee protection. Because of its financial vulnerability and dependence on donor governments and host states, the agency's actions are clearly shaped by the interests of governments. The UNHCR finds it difficult to learn from past mistakes and it lacks strong policy research and strategic thinking capacities. The author offers policy recommendations aimed at making UNHCR more effective and accountable in its central function of protecting refugees.
Gil Loescher
- Published in print:
- 2001
- Published Online:
- November 2003
- ISBN:
- 9780199246915
- eISBN:
- 9780191599781
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0199246912.003.0005
- Subject:
- Political Science, International Relations and Politics
The 1960s brought fundamental changes to the UN system of refugee assistance and protection. The developing world replaced Europe as the central focus of the UNHCR's world. The expansion of the UNHCR ...
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The 1960s brought fundamental changes to the UN system of refugee assistance and protection. The developing world replaced Europe as the central focus of the UNHCR's world. The expansion of the UNHCR under the third High Commissioner, Felix Schnyder, coincided with the decolonization and the ensuing emergence of newly independent states in Africa and Asia. Using his ‘good offices’, Schnyder undertook a de facto expansion of the UNHCR's refugee definition and through the development of rural settlement schemes and ‘zonal’ development, progressively increased the range of the services UNHCR provided both to refugees and to host governments.Less
The 1960s brought fundamental changes to the UN system of refugee assistance and protection. The developing world replaced Europe as the central focus of the UNHCR's world. The expansion of the UNHCR under the third High Commissioner, Felix Schnyder, coincided with the decolonization and the ensuing emergence of newly independent states in Africa and Asia. Using his ‘good offices’, Schnyder undertook a de facto expansion of the UNHCR's refugee definition and through the development of rural settlement schemes and ‘zonal’ development, progressively increased the range of the services UNHCR provided both to refugees and to host governments.
Harry Suhl
- Published in print:
- 2007
- Published Online:
- January 2010
- ISBN:
- 9780198528029
- eISBN:
- 9780191713545
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198528029.001.0001
- Subject:
- Physics, Condensed Matter Physics / Materials
Electrons in solids behave like microscopic bar magnets, and in certain solids these align to produce macroscopic magnetizations. This book deals with the dynamics of this magnetization field. It ...
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Electrons in solids behave like microscopic bar magnets, and in certain solids these align to produce macroscopic magnetizations. This book deals with the dynamics of this magnetization field. It addresses questions of microscopic mechanism only to the extent that residual interactions of the magnetic moments with other degrees of freedom of the host solid affect the dynamics, particularly the dissipative aspects. Several of these damping mechanisms are evaluated here for their effect on the equations of the magnetization dynamics. These dynamics are intrinsically nonlinear. This is important in the applications, particularly magnetic recording, which involves very large motion of the magnetization, well beyond the validity of linearized (small motion) approximations or limited extensions thereof. Therefore nonlinear solution methods are emphasized, but with only minimal use of numerical simulation.Less
Electrons in solids behave like microscopic bar magnets, and in certain solids these align to produce macroscopic magnetizations. This book deals with the dynamics of this magnetization field. It addresses questions of microscopic mechanism only to the extent that residual interactions of the magnetic moments with other degrees of freedom of the host solid affect the dynamics, particularly the dissipative aspects. Several of these damping mechanisms are evaluated here for their effect on the equations of the magnetization dynamics. These dynamics are intrinsically nonlinear. This is important in the applications, particularly magnetic recording, which involves very large motion of the magnetization, well beyond the validity of linearized (small motion) approximations or limited extensions thereof. Therefore nonlinear solution methods are emphasized, but with only minimal use of numerical simulation.
Phil Almond, Trevor Colling, Tony Edwards, and Anthony Ferner
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780199274635
- eISBN:
- 9780191706530
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199274635.003.0013
- Subject:
- Business and Management, HRM / IR
This concluding chapter reviews the evidence gathered in the case studies, and contemplates their contribution to the understanding of country of origin, host country, sectoral, and global dominance ...
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This concluding chapter reviews the evidence gathered in the case studies, and contemplates their contribution to the understanding of country of origin, host country, sectoral, and global dominance effects in the management of human resources within US multinationals. It also suggests directions for future research in the area.Less
This concluding chapter reviews the evidence gathered in the case studies, and contemplates their contribution to the understanding of country of origin, host country, sectoral, and global dominance effects in the management of human resources within US multinationals. It also suggests directions for future research in the area.
Anthony Ferner and Phil Almond
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780199274635
- eISBN:
- 9780191706530
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199274635.003.0001
- Subject:
- Business and Management, HRM / IR
This chapter explains the background and rationale behind the study of the management of international HR and employment relations in US multinationals in four European host countries: the UK, ...
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This chapter explains the background and rationale behind the study of the management of international HR and employment relations in US multinationals in four European host countries: the UK, Germany, Ireland, and Spain.Less
This chapter explains the background and rationale behind the study of the management of international HR and employment relations in US multinationals in four European host countries: the UK, Germany, Ireland, and Spain.
Tony Edwards, Paddy Gunnigle, Javier Quintanilla, and Hartmut Wächter
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780199274635
- eISBN:
- 9780191706530
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199274635.003.0004
- Subject:
- Business and Management, HRM / IR
This chapter establishes the distinctive characteristics of the four host business systems: the UK, Germany, Ireland, and Spain. After providing an overview of the role of foreign, particularly US, ...
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This chapter establishes the distinctive characteristics of the four host business systems: the UK, Germany, Ireland, and Spain. After providing an overview of the role of foreign, particularly US, multinationals within each of the four economies, it establishes the key aspects of the industrial relations systems in each case, particularly those that contrast with the American system. Building on this, the chapter provides an analysis of the extent to which each of the countries are likely to be ‘receptive’ to the introduction of American-style employment practices.Less
This chapter establishes the distinctive characteristics of the four host business systems: the UK, Germany, Ireland, and Spain. After providing an overview of the role of foreign, particularly US, multinationals within each of the four economies, it establishes the key aspects of the industrial relations systems in each case, particularly those that contrast with the American system. Building on this, the chapter provides an analysis of the extent to which each of the countries are likely to be ‘receptive’ to the introduction of American-style employment practices.
Joshua S. Weitz
- Published in print:
- 2016
- Published Online:
- October 2017
- ISBN:
- 9780691161549
- eISBN:
- 9781400873968
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691161549.003.0004
- Subject:
- Biology, Disease Ecology / Epidemiology
This chapter discusses the evolutionary dynamics of viruses. Preexisting variation in host phenotypes include variants with different levels of susceptibility to viruses, including complete ...
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This chapter discusses the evolutionary dynamics of viruses. Preexisting variation in host phenotypes include variants with different levels of susceptibility to viruses, including complete resistance. Formative studies of the basis of the mutation rate relied upon virus–host interactions and the possibility of the evolution of resistance to infection. Viruses represent a strong selective pressure and can induce evolution among hosts. Host evolution, as induced by viruses, includes novel forms of ecological dynamics, including cryptic dynamics. Infection of hosts represents a strong selective pressure for viruses. Viruses that differ in their life history traits vary in their fitness and can invade and replace existing viral strains. The latent period represents a model trait for the further study of the evolution of intermediate phenotypes. Evolution among other traits is also possible, including who infects whom.Less
This chapter discusses the evolutionary dynamics of viruses. Preexisting variation in host phenotypes include variants with different levels of susceptibility to viruses, including complete resistance. Formative studies of the basis of the mutation rate relied upon virus–host interactions and the possibility of the evolution of resistance to infection. Viruses represent a strong selective pressure and can induce evolution among hosts. Host evolution, as induced by viruses, includes novel forms of ecological dynamics, including cryptic dynamics. Infection of hosts represents a strong selective pressure for viruses. Viruses that differ in their life history traits vary in their fitness and can invade and replace existing viral strains. The latent period represents a model trait for the further study of the evolution of intermediate phenotypes. Evolution among other traits is also possible, including who infects whom.
Leslie A. Real and James E. Childs
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780198567080
- eISBN:
- 9780191717871
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567080.003.0012
- Subject:
- Biology, Disease Ecology / Epidemiology
As new species invade novel geographic regions, they have the propensity to reorganize multi-species community interactions. The expansion of the rabies virus in Europe and across the eastern United ...
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As new species invade novel geographic regions, they have the propensity to reorganize multi-species community interactions. The expansion of the rabies virus in Europe and across the eastern United States provides a model system for comparing the linkage between community dynamics and the spatio-temporal dynamics of an invading parasite and its hosts. The European rabies epizootic has been largely restricted to a single terrestrial carnivore host — the red fox — while the US rabies epizootic has involved multiple terrestrial carnivore hosts including raccoons, foxes, skunks, coyotes, and domestic animals. This chapter reviews mathematical models that predict the spatio-temporal patterns of rabies occurring in different reservoir hosts, and explores the implications of the geographic range expansion of the rabies virus within a specific host — the raccoon — on host-shift and spill-over dynamics among alternate hosts.Less
As new species invade novel geographic regions, they have the propensity to reorganize multi-species community interactions. The expansion of the rabies virus in Europe and across the eastern United States provides a model system for comparing the linkage between community dynamics and the spatio-temporal dynamics of an invading parasite and its hosts. The European rabies epizootic has been largely restricted to a single terrestrial carnivore host — the red fox — while the US rabies epizootic has involved multiple terrestrial carnivore hosts including raccoons, foxes, skunks, coyotes, and domestic animals. This chapter reviews mathematical models that predict the spatio-temporal patterns of rabies occurring in different reservoir hosts, and explores the implications of the geographic range expansion of the rabies virus within a specific host — the raccoon — on host-shift and spill-over dynamics among alternate hosts.
Joseph Lemire, Trevor F. Moraes, Vahid Fa Andisi, and Anthony B. Schryvers
- Published in print:
- 2015
- Published Online:
- May 2016
- ISBN:
- 9780262029193
- eISBN:
- 9780262327619
- Item type:
- chapter
- Publisher:
- The MIT Press
- DOI:
- 10.7551/mitpress/9780262029193.003.0002
- Subject:
- Public Health and Epidemiology, Public Health
There is a complex interplay between the vertebrate host and the microbes that inhabit its mucosal surfaces in their competition for essential metal ions. Mucosal surfaces in the host constitute an ...
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There is a complex interplay between the vertebrate host and the microbes that inhabit its mucosal surfaces in their competition for essential metal ions. Mucosal surfaces in the host constitute an array of diverse ecological niches that vary substantially in the availability of metal ions from the external environment and from the host. The microbes that inhabit different mucosal surfaces vary in the degree to which they are uniquely adapted to, and are restricted to, the host mucosal environment. This chapter reviews current understanding of metal ion homeostasis in the host, the mechanisms of metal ion acquisition in microbes, and the degree to which the specific mucosal niche impacts the repertoire of metal ion acquisition mechanisms that the microbes possess.Less
There is a complex interplay between the vertebrate host and the microbes that inhabit its mucosal surfaces in their competition for essential metal ions. Mucosal surfaces in the host constitute an array of diverse ecological niches that vary substantially in the availability of metal ions from the external environment and from the host. The microbes that inhabit different mucosal surfaces vary in the degree to which they are uniquely adapted to, and are restricted to, the host mucosal environment. This chapter reviews current understanding of metal ion homeostasis in the host, the mechanisms of metal ion acquisition in microbes, and the degree to which the specific mucosal niche impacts the repertoire of metal ion acquisition mechanisms that the microbes possess.
Marisa Tellez
- Published in print:
- 2013
- Published Online:
- May 2014
- ISBN:
- 9780520098893
- eISBN:
- 9780520957367
- Item type:
- chapter
- Publisher:
- University of California Press
- DOI:
- 10.1525/california/9780520098893.003.0005
- Subject:
- Biology, Animal Biology
Patterns of parasitism among crocodilian species include generalist and specialists. Overall, there are fewer generalist parasite species (∼99) than host-specific species (∼103). Explanations for ...
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Patterns of parasitism among crocodilian species include generalist and specialists. Overall, there are fewer generalist parasite species (∼99) than host-specific species (∼103). Explanations for overall patterns are reviewed.Less
Patterns of parasitism among crocodilian species include generalist and specialists. Overall, there are fewer generalist parasite species (∼99) than host-specific species (∼103). Explanations for overall patterns are reviewed.
Frank H. Herbstein
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198526605
- eISBN:
- 9780191712142
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198526605.003.0006
- Subject:
- Physics, Crystallography: Physics
Crystalline tunnel inclusion complexes have one-dimensional tunnels in their structures. The host molecules, which constitute the matrix, may be bonded together by directional bonds or van der Waals ...
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Crystalline tunnel inclusion complexes have one-dimensional tunnels in their structures. The host molecules, which constitute the matrix, may be bonded together by directional bonds or van der Waals forces. The guest molecules in the tunnels generally interact with the host molecules by van der Waals forces, although some examples of host-guest hydrogen bonding are known. The nature of the guest appears to be limited only by the size and shape of the tunnel available, although there are some examples of specific host-guest interactions. The arrangements of the host molecules in the matrix are generally different from those in the neat hosts, and in this situation, the tunnel inclusion complexes are separate phases. The Bishop-Dance complexes, which are primary solid solution of guest in host, are exceptions. Most of the examples quoted show the effects of interaction between host and guest, which manifest themselves as minor changes in cell dimensions of isomorphous crystals or as distortions of a basic crystal structure type. Guest molecules are generally disordered in the tunnels at room temperature but order on cooling, often in a number of stages accompanied by interaction with and distortion of the framework, usually manifested as phase transformations. Diffraction patterns from many complexes are composed of separate contributions from the host framework and the guest arrangement, both being modified by mutual interaction of host and guest. The complicated effects that can ensue are illustrated.Less
Crystalline tunnel inclusion complexes have one-dimensional tunnels in their structures. The host molecules, which constitute the matrix, may be bonded together by directional bonds or van der Waals forces. The guest molecules in the tunnels generally interact with the host molecules by van der Waals forces, although some examples of host-guest hydrogen bonding are known. The nature of the guest appears to be limited only by the size and shape of the tunnel available, although there are some examples of specific host-guest interactions. The arrangements of the host molecules in the matrix are generally different from those in the neat hosts, and in this situation, the tunnel inclusion complexes are separate phases. The Bishop-Dance complexes, which are primary solid solution of guest in host, are exceptions. Most of the examples quoted show the effects of interaction between host and guest, which manifest themselves as minor changes in cell dimensions of isomorphous crystals or as distortions of a basic crystal structure type. Guest molecules are generally disordered in the tunnels at room temperature but order on cooling, often in a number of stages accompanied by interaction with and distortion of the framework, usually manifested as phase transformations. Diffraction patterns from many complexes are composed of separate contributions from the host framework and the guest arrangement, both being modified by mutual interaction of host and guest. The complicated effects that can ensue are illustrated.
Gregory P. Cheplick and Stanley H. Faeth
- Published in print:
- 2009
- Published Online:
- January 2009
- ISBN:
- 9780195308082
- eISBN:
- 9780199867462
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195308082.003.0004
- Subject:
- Biology, Ecology
For ongoing coevolution of the grass-endophyte symbiosis through the agents of natural selection, there must be genetic variation within populations for both host and endophyte. The breeding systems ...
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For ongoing coevolution of the grass-endophyte symbiosis through the agents of natural selection, there must be genetic variation within populations for both host and endophyte. The breeding systems of both symbiotic partners influence the distribution and level of genetic variation within populations. Traditional reaction norms and symbiotic interaction norms can be useful in depicting host genotype interactions with environment and infection. Examples are provided for both agronomic and native grass-endophyte symbioses. Endophytes can also modulate phenotypic plasticity of their grass hosts in relation to environmental variation. There is evidence that endophyte genotypes (haplotypes) can differ significantly in their impact on host growth and physiology. Genetic diversity of endophyte isolates has been quantified using isozymes and DNA markers. Host-endophyte compatibility can vary among endophytes and their host grasses as revealed by reciprocal inoculation experiments using fungal isolates from different host populations or species. Multistrain infections of single grass hosts and fungal hybridization within individual hosts have been determined for some symbioses. Genetic variation in both host and endophyte will expedite the continued coevolution of the symbiosis.Less
For ongoing coevolution of the grass-endophyte symbiosis through the agents of natural selection, there must be genetic variation within populations for both host and endophyte. The breeding systems of both symbiotic partners influence the distribution and level of genetic variation within populations. Traditional reaction norms and symbiotic interaction norms can be useful in depicting host genotype interactions with environment and infection. Examples are provided for both agronomic and native grass-endophyte symbioses. Endophytes can also modulate phenotypic plasticity of their grass hosts in relation to environmental variation. There is evidence that endophyte genotypes (haplotypes) can differ significantly in their impact on host growth and physiology. Genetic diversity of endophyte isolates has been quantified using isozymes and DNA markers. Host-endophyte compatibility can vary among endophytes and their host grasses as revealed by reciprocal inoculation experiments using fungal isolates from different host populations or species. Multistrain infections of single grass hosts and fungal hybridization within individual hosts have been determined for some symbioses. Genetic variation in both host and endophyte will expedite the continued coevolution of the symbiosis.
Gregory P. Cheplick and Stanley H. Faeth
- Published in print:
- 2009
- Published Online:
- January 2009
- ISBN:
- 9780195308082
- eISBN:
- 9780199867462
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195308082.003.0005
- Subject:
- Biology, Ecology
Because systemic endophytes predominantly inhabit caespitose perennial grasses and seedling recruitment may be relatively scarce, understanding how infection alters the population dynamics and ...
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Because systemic endophytes predominantly inhabit caespitose perennial grasses and seedling recruitment may be relatively scarce, understanding how infection alters the population dynamics and evolutionary ecology of grass populations is challenging. Thus, genet and ramet survival, and size and seedling recruitment must be considered. In some cases, infected grasses increase in numbers and relative frequency while in others infection is neutral or negative with respect to relative frequencies, much like the case with individual host-endophyte interactions. In long-term studies of perennial ryegrass, infection can increase tiller production, change allometric relationships between growth and reproduction with grass ontogeny, and impact the dynamics of the grass population. Further complicating population dynamics of infected and uninfected grasses is the largely unknown dynamics of infected seeds in the seed bank. Nonetheless, this chapter suggests that changes in genotypic sorting in most grass populations based upon infection status is likely to be a relatively slow process that requires long-term experiments to observe. The observation that infection frequencies are highly variable among grass populations and among grass species suggests that there are many genetic, ecological, and geographical (e.g., metapopulation dynamics) factors that determine whether infected plants persist, increase or decline relative to uninfected counterparts. Like other species interactions, Thompson's (1994) geographic mosaic model of coevolution provides a conceptual basis for coevolution of grass-endophyte interactions. Local selection pressures acting on local populations shape endophyte-host grass interactions, and interacting populations may evolve antagonistically or mutualistically such that a broad characterization of the endophyte-grass interaction may prove difficult.Less
Because systemic endophytes predominantly inhabit caespitose perennial grasses and seedling recruitment may be relatively scarce, understanding how infection alters the population dynamics and evolutionary ecology of grass populations is challenging. Thus, genet and ramet survival, and size and seedling recruitment must be considered. In some cases, infected grasses increase in numbers and relative frequency while in others infection is neutral or negative with respect to relative frequencies, much like the case with individual host-endophyte interactions. In long-term studies of perennial ryegrass, infection can increase tiller production, change allometric relationships between growth and reproduction with grass ontogeny, and impact the dynamics of the grass population. Further complicating population dynamics of infected and uninfected grasses is the largely unknown dynamics of infected seeds in the seed bank. Nonetheless, this chapter suggests that changes in genotypic sorting in most grass populations based upon infection status is likely to be a relatively slow process that requires long-term experiments to observe. The observation that infection frequencies are highly variable among grass populations and among grass species suggests that there are many genetic, ecological, and geographical (e.g., metapopulation dynamics) factors that determine whether infected plants persist, increase or decline relative to uninfected counterparts. Like other species interactions, Thompson's (1994) geographic mosaic model of coevolution provides a conceptual basis for coevolution of grass-endophyte interactions. Local selection pressures acting on local populations shape endophyte-host grass interactions, and interacting populations may evolve antagonistically or mutualistically such that a broad characterization of the endophyte-grass interaction may prove difficult.
Jaap Goudsmit
- Published in print:
- 2004
- Published Online:
- September 2007
- ISBN:
- 9780195130348
- eISBN:
- 9780199790166
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195130348.003.0012
- Subject:
- Biology, Microbiology
This chapter discusses several issues concerning viruses. These include the increasing threat to humans posed by viruses, the settlement of virus families in the population, and the spread of viruses ...
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This chapter discusses several issues concerning viruses. These include the increasing threat to humans posed by viruses, the settlement of virus families in the population, and the spread of viruses when their hosts are older. The chapter also discusses the fact that viruses spread easily when dependant upon the conditions under which a host lives or is forced to live. Viruses destroy life and protect it at the same time, and the failure to defend against virus invasion with vaccines reduces the chances for survival of many people on several continents.Less
This chapter discusses several issues concerning viruses. These include the increasing threat to humans posed by viruses, the settlement of virus families in the population, and the spread of viruses when their hosts are older. The chapter also discusses the fact that viruses spread easily when dependant upon the conditions under which a host lives or is forced to live. Viruses destroy life and protect it at the same time, and the failure to defend against virus invasion with vaccines reduces the chances for survival of many people on several continents.
Sharon K. Collinge and Chris Ray (eds)
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780198567080
- eISBN:
- 9780191717871
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198567080.001.0001
- Subject:
- Biology, Disease Ecology / Epidemiology
Many infectious diseases of recent concern, including malaria, cholera, plague, and Lyme disease, have emerged from complex ecological communities involving multiple hosts and their associated ...
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Many infectious diseases of recent concern, including malaria, cholera, plague, and Lyme disease, have emerged from complex ecological communities involving multiple hosts and their associated parasites. Several of these diseases appear to be influenced by human impacts on the environment, for example intensive agriculture, clear-cut forestry, and habitat loss, and fragmentation. Such environmental impacts may affect many species at trophic levels below or above the host community. Thus, the prevalence of both human and wildlife diseases may alter in unanticipated ways as a result of changes in the structure and composition of ecological communities. This book highlights exciting advances in theoretical and empirical research aimed towards a better understanding of the importance of community structure in the emergence of infectious diseases. To date, research on host-parasite systems has tended to explore only a limited set of community interactions, and little effort has been devoted to addressing complications, such as multiple-host-multiple-parasite systems; sequential hosts acting on different trophic levels; alternate hosts with spatially varying interactions; or stochastic effects resulting from small population size in at least one alternate host species. The chapters in this book illustrate aspects of community ecology that influence pathogen transmission rates and disease dynamics in a wide variety of study systems. It communicates a clear message: studies of epidemiology can be approached from the perspective of community ecology, and students of community ecology can contribute significantly to epidemiology.Less
Many infectious diseases of recent concern, including malaria, cholera, plague, and Lyme disease, have emerged from complex ecological communities involving multiple hosts and their associated parasites. Several of these diseases appear to be influenced by human impacts on the environment, for example intensive agriculture, clear-cut forestry, and habitat loss, and fragmentation. Such environmental impacts may affect many species at trophic levels below or above the host community. Thus, the prevalence of both human and wildlife diseases may alter in unanticipated ways as a result of changes in the structure and composition of ecological communities. This book highlights exciting advances in theoretical and empirical research aimed towards a better understanding of the importance of community structure in the emergence of infectious diseases. To date, research on host-parasite systems has tended to explore only a limited set of community interactions, and little effort has been devoted to addressing complications, such as multiple-host-multiple-parasite systems; sequential hosts acting on different trophic levels; alternate hosts with spatially varying interactions; or stochastic effects resulting from small population size in at least one alternate host species. The chapters in this book illustrate aspects of community ecology that influence pathogen transmission rates and disease dynamics in a wide variety of study systems. It communicates a clear message: studies of epidemiology can be approached from the perspective of community ecology, and students of community ecology can contribute significantly to epidemiology.
Anders Pape Møller
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198529873
- eISBN:
- 9780191712777
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529873.003.0004
- Subject:
- Biology, Disease Ecology / Epidemiology
Parasites can have a dramatic effect on the host population and regulate host populations under specific cases. This chapter reviews the basic microparasite and macroparasite models, and the ...
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Parasites can have a dramatic effect on the host population and regulate host populations under specific cases. This chapter reviews the basic microparasite and macroparasite models, and the conditions that lead to regulation. It considers transient and at times more interesting features of parasite-host relationships. Examples from natural systems are considered and parasite-mediated competition is reviewed. The importance of immuno-suppression and cross-immunity in relation to rabbit parasites is considered as a case study.Less
Parasites can have a dramatic effect on the host population and regulate host populations under specific cases. This chapter reviews the basic microparasite and macroparasite models, and the conditions that lead to regulation. It considers transient and at times more interesting features of parasite-host relationships. Examples from natural systems are considered and parasite-mediated competition is reviewed. The importance of immuno-suppression and cross-immunity in relation to rabbit parasites is considered as a case study.
Michael V. K. Sukhdeo and Alexander D. Hernandez
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198529873
- eISBN:
- 9780191712777
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198529873.003.0005
- Subject:
- Biology, Disease Ecology / Epidemiology
Food webs are theoretical abstractions of the complex linkages and interactions that are thought to occur in nature. Although few real food webs have actually been characterized scientifically, there ...
More
Food webs are theoretical abstractions of the complex linkages and interactions that are thought to occur in nature. Although few real food webs have actually been characterized scientifically, there is a large body of literature on the processes that contribute towards complexity and stability in webs. Food webs are generally thought of as ‘what eats what’ webs, but parasites are not usually incorporated into webs even though parasitism is a feeding strategy shared by a majority of species on earth (70%). This chapter examines major ideas on the roles of parasites in food webs, starting with Elton’s (1927) idea that parasites are analogous to predators. It describes some general patterns of parasite web structure (e.g., inverted pyramid of numbers and body size hypotheses) using both available published data and data from studies on food webs in freshwater streams in New Jersey.Less
Food webs are theoretical abstractions of the complex linkages and interactions that are thought to occur in nature. Although few real food webs have actually been characterized scientifically, there is a large body of literature on the processes that contribute towards complexity and stability in webs. Food webs are generally thought of as ‘what eats what’ webs, but parasites are not usually incorporated into webs even though parasitism is a feeding strategy shared by a majority of species on earth (70%). This chapter examines major ideas on the roles of parasites in food webs, starting with Elton’s (1927) idea that parasites are analogous to predators. It describes some general patterns of parasite web structure (e.g., inverted pyramid of numbers and body size hypotheses) using both available published data and data from studies on food webs in freshwater streams in New Jersey.
