Sharan Jagpal
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780195371055
- eISBN:
- 9780199870745
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195371055.003.0023
- Subject:
- Business and Management, Marketing
This chapter shows how multinational firms can use marketing-finance fusion to choose international strategies. It discusses the pros and cons of international diversification to privately and ...
More
This chapter shows how multinational firms can use marketing-finance fusion to choose international strategies. It discusses the pros and cons of international diversification to privately and publicly held firms, whether or not the firm should choose country-specific product designs, how the firm should measure and reward the performances of its country managers, what type of organizational structure the firm should use, how the firm should choose an outsourcing strategy, and what performance metrics the firm should use to measure and reward managerial performance in its outsourcing centers.Less
This chapter shows how multinational firms can use marketing-finance fusion to choose international strategies. It discusses the pros and cons of international diversification to privately and publicly held firms, whether or not the firm should choose country-specific product designs, how the firm should measure and reward the performances of its country managers, what type of organizational structure the firm should use, how the firm should choose an outsourcing strategy, and what performance metrics the firm should use to measure and reward managerial performance in its outsourcing centers.
Niels Christian Hvidt
- Published in print:
- 2007
- Published Online:
- May 2007
- ISBN:
- 9780195314472
- eISBN:
- 9780199785346
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195314472.003.0002
- Subject:
- Religion, Theology
Although Christian prophecy has had a significant impact in the life of the church, it has received rather scarce theological elaboration. This is strange, for with Hans Urs von Balthasar one can ...
More
Although Christian prophecy has had a significant impact in the life of the church, it has received rather scarce theological elaboration. This is strange, for with Hans Urs von Balthasar one can rightly ask why God continues to provide prophetic revelations, when apparently they hardly need to be heeded by the church and theology. One of the reasons for the scarce theological elaboration of prophecy is that theology has been highly diversified and specialized in different sub-disciplines. Such necessary specialization constitutes a challenge for the unity of theology. It equally constitutes a challenge for Christian prophecy that calls for diversified theological treatment including dogmatic theology, fundamental theology, exegesis, church history, and mystical theology.Less
Although Christian prophecy has had a significant impact in the life of the church, it has received rather scarce theological elaboration. This is strange, for with Hans Urs von Balthasar one can rightly ask why God continues to provide prophetic revelations, when apparently they hardly need to be heeded by the church and theology. One of the reasons for the scarce theological elaboration of prophecy is that theology has been highly diversified and specialized in different sub-disciplines. Such necessary specialization constitutes a challenge for the unity of theology. It equally constitutes a challenge for Christian prophecy that calls for diversified theological treatment including dogmatic theology, fundamental theology, exegesis, church history, and mystical theology.
Michael Doebeli
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128931
- eISBN:
- 9781400838936
- Item type:
- book
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128931.001.0001
- Subject:
- Biology, Biodiversity / Conservation Biology
Understanding the mechanisms driving biological diversity remains a central problem in ecology and evolutionary biology. Traditional explanations assume that differences in selection pressures lead ...
More
Understanding the mechanisms driving biological diversity remains a central problem in ecology and evolutionary biology. Traditional explanations assume that differences in selection pressures lead to different adaptations in geographically separated locations. This book takes a different approach and explores adaptive diversification—diversification rooted in ecological interactions and frequency-dependent selection. In any ecosystem, birth and death rates of individuals are affected by interactions with other individuals. What is an advantageous phenotype therefore depends on the phenotype of other individuals, and it may often be best to be ecologically different from the majority phenotype. Such rare-type advantage is a hallmark of frequency-dependent selection and opens the scope for processes of diversification that require ecological contact rather than geographical isolation. This book investigates adaptive diversification using the mathematical framework of adaptive dynamics. Evolutionary branching is a paradigmatic feature of adaptive dynamics that serves as a basic metaphor for adaptive diversification, and the book explores the scope of evolutionary branching in many different ecological scenarios, including models of coevolution, cooperation, and cultural evolution. It also uses alternative modeling approaches. Stochastic, individual-based models are particularly useful for studying adaptive speciation in sexual populations, and partial differential equation models confirm the pervasiveness of adaptive diversification. Showing that frequency-dependent interactions are an important driver of biological diversity, the book provides a comprehensive theoretical treatment of adaptive diversification.Less
Understanding the mechanisms driving biological diversity remains a central problem in ecology and evolutionary biology. Traditional explanations assume that differences in selection pressures lead to different adaptations in geographically separated locations. This book takes a different approach and explores adaptive diversification—diversification rooted in ecological interactions and frequency-dependent selection. In any ecosystem, birth and death rates of individuals are affected by interactions with other individuals. What is an advantageous phenotype therefore depends on the phenotype of other individuals, and it may often be best to be ecologically different from the majority phenotype. Such rare-type advantage is a hallmark of frequency-dependent selection and opens the scope for processes of diversification that require ecological contact rather than geographical isolation. This book investigates adaptive diversification using the mathematical framework of adaptive dynamics. Evolutionary branching is a paradigmatic feature of adaptive dynamics that serves as a basic metaphor for adaptive diversification, and the book explores the scope of evolutionary branching in many different ecological scenarios, including models of coevolution, cooperation, and cultural evolution. It also uses alternative modeling approaches. Stochastic, individual-based models are particularly useful for studying adaptive speciation in sexual populations, and partial differential equation models confirm the pervasiveness of adaptive diversification. Showing that frequency-dependent interactions are an important driver of biological diversity, the book provides a comprehensive theoretical treatment of adaptive diversification.
Gary Herrigel
- Published in print:
- 2010
- Published Online:
- September 2010
- ISBN:
- 9780199557738
- eISBN:
- 9780191720871
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199557738.003.0005
- Subject:
- Business and Management, Political Economy
Chapter introduces the problem of vertical disintegration, outlining the basic competitive dynamics that give rise to it. A five fold typology of supplier-customer relations is presented: arms ...
More
Chapter introduces the problem of vertical disintegration, outlining the basic competitive dynamics that give rise to it. A five fold typology of supplier-customer relations is presented: arms length, captured, modular, relational contracts and sustained contingent collaboration. Sustained contingent collaboration is the modal relation in the current historical environment. The range of supplier strategies and public policies that are emerging to cope with sustained contingent collaboration are extensively discussed.Less
Chapter introduces the problem of vertical disintegration, outlining the basic competitive dynamics that give rise to it. A five fold typology of supplier-customer relations is presented: arms length, captured, modular, relational contracts and sustained contingent collaboration. Sustained contingent collaboration is the modal relation in the current historical environment. The range of supplier strategies and public policies that are emerging to cope with sustained contingent collaboration are extensively discussed.
Michael Doebeli
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128931
- eISBN:
- 9781400838936
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128931.003.0008
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter examines adaptive diversification in language and religion. The historic record contains many examples of the types of diversification occurring in these models. Diversification in ...
More
This chapter examines adaptive diversification in language and religion. The historic record contains many examples of the types of diversification occurring in these models. Diversification in languages has been rampant throughout history, and must have often occurred under substantial contact between hosts of diverging language memes. Similarly, it seems clear that religious diversification has often occurred, and continuous to occur, under conditions of substantial contact. The models illustrate that diversifying processes should be expected to operate whenever the likelihood of secession from a dominant culture increases with increasing dominance of the mainstream culture. Intuitively, it is not hard to imagine that the attractiveness of a culture diminishes as the culture becomes more dominant, dogmatic, and perhaps oppressive, and that the desire to stand out and be different increases in increasingly conformist cultures.Less
This chapter examines adaptive diversification in language and religion. The historic record contains many examples of the types of diversification occurring in these models. Diversification in languages has been rampant throughout history, and must have often occurred under substantial contact between hosts of diverging language memes. Similarly, it seems clear that religious diversification has often occurred, and continuous to occur, under conditions of substantial contact. The models illustrate that diversifying processes should be expected to operate whenever the likelihood of secession from a dominant culture increases with increasing dominance of the mainstream culture. Intuitively, it is not hard to imagine that the attractiveness of a culture diminishes as the culture becomes more dominant, dogmatic, and perhaps oppressive, and that the desire to stand out and be different increases in increasingly conformist cultures.
Michael L. Arnold
- Published in print:
- 2008
- Published Online:
- January 2009
- ISBN:
- 9780199539581
- eISBN:
- 9780191716225
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199539581.001.0001
- Subject:
- Biology, Animal Biology, Evolutionary Biology / Genetics
This book is an exploration of how the transfer of genes between divergent lineages — through a diverse array of mechanisms — has affected, and continues to affect, humans. In particular, it is a ...
More
This book is an exploration of how the transfer of genes between divergent lineages — through a diverse array of mechanisms — has affected, and continues to affect, humans. In particular, it is a journey into the data that support the hypothesis that Homo sapiens as well as those organisms upon which it depends for survival and battles against for existence are marked by mosaic genomes. This mosaicism reflects the rampant (as reflected by the proportion of organisms that illustrate this process) exchange of genetic material during evolutionary diversification. This is the underlying hypothesis for this book. The book follows in the various chapters that it also reflects the consistent observation made when the genomes of organisms are mined for genetic variation.Less
This book is an exploration of how the transfer of genes between divergent lineages — through a diverse array of mechanisms — has affected, and continues to affect, humans. In particular, it is a journey into the data that support the hypothesis that Homo sapiens as well as those organisms upon which it depends for survival and battles against for existence are marked by mosaic genomes. This mosaicism reflects the rampant (as reflected by the proportion of organisms that illustrate this process) exchange of genetic material during evolutionary diversification. This is the underlying hypothesis for this book. The book follows in the various chapters that it also reflects the consistent observation made when the genomes of organisms are mined for genetic variation.
Frank Dikötter
- Published in print:
- 2008
- Published Online:
- September 2011
- ISBN:
- 9789622099203
- eISBN:
- 9789882206595
- Item type:
- chapter
- Publisher:
- Hong Kong University Press
- DOI:
- 10.5790/hongkong/9789622099203.003.0006
- Subject:
- History, Asian History
Glasnost in the Soviet Union, kaifang in China, or doi moi in Vietnam: “openness” in socialist states has become such an inflated term of political ...
More
Glasnost in the Soviet Union, kaifang in China, or doi moi in Vietnam: “openness” in socialist states has become such an inflated term of political propaganda that one tends to forget that prerevolutionary regimes were often marked by a much higher degree of cosmopolitanism. It has been argued that globalisation was a vector of cultural diversification, which, in turn, was best supported by increased globalisation. It is also indicated that increased interdependence with the rest of the world might eventually lead to participatory politics and the rule of law, while on the other hand the pessimistic view points at the use of a relative degree of economic openness to shore up the power of a privileged elite at the expense of the civil liberties of ordinary people. Whatever the case may be, the overlooked cosmopolitan experience of the republican era is of even greater relevance today, now that even in the People's Republic globalisation rather than revolution has become the guiding issue for the twenty-first century.Less
Glasnost in the Soviet Union, kaifang in China, or doi moi in Vietnam: “openness” in socialist states has become such an inflated term of political propaganda that one tends to forget that prerevolutionary regimes were often marked by a much higher degree of cosmopolitanism. It has been argued that globalisation was a vector of cultural diversification, which, in turn, was best supported by increased globalisation. It is also indicated that increased interdependence with the rest of the world might eventually lead to participatory politics and the rule of law, while on the other hand the pessimistic view points at the use of a relative degree of economic openness to shore up the power of a privileged elite at the expense of the civil liberties of ordinary people. Whatever the case may be, the overlooked cosmopolitan experience of the republican era is of even greater relevance today, now that even in the People's Republic globalisation rather than revolution has become the guiding issue for the twenty-first century.
Robin J. Wootton and David J.S. Newman
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780199230693
- eISBN:
- 9780191710889
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199230693.003.0020
- Subject:
- Biology, Ecology, Animal Biology
This chapter shows how the patterns of evolution and diversification of odonatoids, and by implication those of other flight-active taxa can be illuminated by studying their flight mechanics. The ...
More
This chapter shows how the patterns of evolution and diversification of odonatoids, and by implication those of other flight-active taxa can be illuminated by studying their flight mechanics. The relationships between flight capabilities and wing and body design are discussed; and the functional significance of familiar wing characters and character states are investigated and compared in a range of extant and extinct odonates, using simple physical models. Convergence in wing shape and in some other characters is shown to be widespread, reflecting similarities in flight behaviour and performance in different taxa throughout the long history of the Superorder. Anagenesis — evolutionary ‘improvement’ — is also widely recognizable. Three important areas for future research are identified: detailed comparative investigations of flight performance; comparative morphometric analysis of functionally interpretable wing and body characters; and detailed Finite Element modelling of selected wing characters, rather than superficial analyses of complete wings.Less
This chapter shows how the patterns of evolution and diversification of odonatoids, and by implication those of other flight-active taxa can be illuminated by studying their flight mechanics. The relationships between flight capabilities and wing and body design are discussed; and the functional significance of familiar wing characters and character states are investigated and compared in a range of extant and extinct odonates, using simple physical models. Convergence in wing shape and in some other characters is shown to be widespread, reflecting similarities in flight behaviour and performance in different taxa throughout the long history of the Superorder. Anagenesis — evolutionary ‘improvement’ — is also widely recognizable. Three important areas for future research are identified: detailed comparative investigations of flight performance; comparative morphometric analysis of functionally interpretable wing and body characters; and detailed Finite Element modelling of selected wing characters, rather than superficial analyses of complete wings.
James Patton
- Published in print:
- 2008
- Published Online:
- March 2012
- ISBN:
- 9780520098664
- eISBN:
- 9780520942592
- Item type:
- book
- Publisher:
- University of California Press
- DOI:
- 10.1525/california/9780520098664.001.0001
- Subject:
- Biology, Animal Biology
This book details the evolutionary history of the desert woodrat complex (lepida group, genus Neotoma) of western North America. The analyses include standard multivariate morphometrics of museum ...
More
This book details the evolutionary history of the desert woodrat complex (lepida group, genus Neotoma) of western North America. The analyses include standard multivariate morphometrics of museum specimens coupled with mitochondrial and nuclear DNA sequences and microsatellite loci. The work also traces the spatial and temporal diversification of this group of desert-dwelling rodents, revising species boundaries and delineating subspecies considered valid.Less
This book details the evolutionary history of the desert woodrat complex (lepida group, genus Neotoma) of western North America. The analyses include standard multivariate morphometrics of museum specimens coupled with mitochondrial and nuclear DNA sequences and microsatellite loci. The work also traces the spatial and temporal diversification of this group of desert-dwelling rodents, revising species boundaries and delineating subspecies considered valid.
Tatsuya Kikutani, Hideshi Itoh, and Osamu Hayashida
- Published in print:
- 2007
- Published Online:
- September 2007
- ISBN:
- 9780199284511
- eISBN:
- 9780191713705
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199284511.003.0008
- Subject:
- Economics and Finance, South and East Asia
This chapter examines the restructuring of Japanese business groups during the 1990s. Using the Basic Survey of Business Structure and Activity, the chapter analyses the business portfolio of ...
More
This chapter examines the restructuring of Japanese business groups during the 1990s. Using the Basic Survey of Business Structure and Activity, the chapter analyses the business portfolio of Japanese firms from the perspective of the group structure of parent and affiliate. While previous studies have examined the net shift in diversification or specialization of business, the chapter also adopts an original approach by looking at the actual flow of entry and exit from business segments. The analysis demonstrates that Japanese business groups engaged in a high level of restructuring during the 1990s, and a growing preference to separate businesses into subsidiaries and affiliated firms rather than managing them in house. Although Japanese firms have no trend toward greater diversification or greater focus on aggregate, entry and exit are important complementary strategies that improve firms.Less
This chapter examines the restructuring of Japanese business groups during the 1990s. Using the Basic Survey of Business Structure and Activity, the chapter analyses the business portfolio of Japanese firms from the perspective of the group structure of parent and affiliate. While previous studies have examined the net shift in diversification or specialization of business, the chapter also adopts an original approach by looking at the actual flow of entry and exit from business segments. The analysis demonstrates that Japanese business groups engaged in a high level of restructuring during the 1990s, and a growing preference to separate businesses into subsidiaries and affiliated firms rather than managing them in house. Although Japanese firms have no trend toward greater diversification or greater focus on aggregate, entry and exit are important complementary strategies that improve firms.
Michael Doebeli
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128931
- eISBN:
- 9781400838936
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128931.003.0002
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter begins by considering the Maynard Smith model. Much of this work concentrated on the genetic mechanisms for assortative mating and reproductive isolation, based on the assumption that ...
More
This chapter begins by considering the Maynard Smith model. Much of this work concentrated on the genetic mechanisms for assortative mating and reproductive isolation, based on the assumption that the underlying niche ecology would generate disruptive selection. However, understanding the conditions under which disruptive selection arises in the first place is equally important, and indeed necessary for assessing whether diversification is a general outcome in the Maynard Smith model. The chapter then shows that disruptive selection and polymorphism are scenarios that occur generically, that is, for a wide range of parameters, in a classical and widely used speciation model. It also provides an introduction to some of the basic concepts of adaptive dynamics theory.Less
This chapter begins by considering the Maynard Smith model. Much of this work concentrated on the genetic mechanisms for assortative mating and reproductive isolation, based on the assumption that the underlying niche ecology would generate disruptive selection. However, understanding the conditions under which disruptive selection arises in the first place is equally important, and indeed necessary for assessing whether diversification is a general outcome in the Maynard Smith model. The chapter then shows that disruptive selection and polymorphism are scenarios that occur generically, that is, for a wide range of parameters, in a classical and widely used speciation model. It also provides an introduction to some of the basic concepts of adaptive dynamics theory.
Michael Doebeli
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128931
- eISBN:
- 9781400838936
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128931.003.0005
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter discusses adaptive diversification due to predator–prey interactions. It has long been recognized that consumption, that is, predation, can not only exert strong selection pressure on ...
More
This chapter discusses adaptive diversification due to predator–prey interactions. It has long been recognized that consumption, that is, predation, can not only exert strong selection pressure on the consumer, but also on the consumed species. However, predation has traditionally received much less attention than competition as a cause for the origin and maintenance of diversity. By using adaptive dynamics theory as well as individual-based models, the chapter then illustrates that adaptive diversification in prey species due to frequency-dependent predator–prey interactions is a theoretically plausible scenario. It also describes conditions for diversification due to predator–prey interactions in classical Lotka–Volterra models, which requires analysis of coevolutionary dynamics between two interacting species, and hence of adaptive dynamics in two-dimensional phenotype spaces.Less
This chapter discusses adaptive diversification due to predator–prey interactions. It has long been recognized that consumption, that is, predation, can not only exert strong selection pressure on the consumer, but also on the consumed species. However, predation has traditionally received much less attention than competition as a cause for the origin and maintenance of diversity. By using adaptive dynamics theory as well as individual-based models, the chapter then illustrates that adaptive diversification in prey species due to frequency-dependent predator–prey interactions is a theoretically plausible scenario. It also describes conditions for diversification due to predator–prey interactions in classical Lotka–Volterra models, which requires analysis of coevolutionary dynamics between two interacting species, and hence of adaptive dynamics in two-dimensional phenotype spaces.
Michael Doebeli
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128931
- eISBN:
- 9781400838936
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128931.003.0006
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter focuses on adaptive diversification due to cooperative interactions. If predation has received less attention than competition as a cause for the origin and maintenance of diversity, ...
More
This chapter focuses on adaptive diversification due to cooperative interactions. If predation has received less attention than competition as a cause for the origin and maintenance of diversity, mutualistic interactions have fared even worse. There is quite a substantial theoretical literature on the ecology of mutualistic interactions, but only a few studies have investigated mutualism as a potential driver of diversification. There is of course a rather huge literature on the evolution of intraspecific cooperation, and many of these models implicitly address the problem of coexistence between cheaters and cooperators, and hence the maintenance of diversity. However, the origin of diversity in cooperative contributions has only recently been investigated. Most models of cooperation assume that cooperators make a costly contribution to a public good, which is then distributed among certain members of the population.Less
This chapter focuses on adaptive diversification due to cooperative interactions. If predation has received less attention than competition as a cause for the origin and maintenance of diversity, mutualistic interactions have fared even worse. There is quite a substantial theoretical literature on the ecology of mutualistic interactions, but only a few studies have investigated mutualism as a potential driver of diversification. There is of course a rather huge literature on the evolution of intraspecific cooperation, and many of these models implicitly address the problem of coexistence between cheaters and cooperators, and hence the maintenance of diversity. However, the origin of diversity in cooperative contributions has only recently been investigated. Most models of cooperation assume that cooperators make a costly contribution to a public good, which is then distributed among certain members of the population.
Michael Doebeli
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128931
- eISBN:
- 9781400838936
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128931.003.0009
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter discusses partial differential equation models. Partial differential equations can describe the dynamics of phenotype distributions of polymorphic populations, and they allow for a ...
More
This chapter discusses partial differential equation models. Partial differential equations can describe the dynamics of phenotype distributions of polymorphic populations, and they allow for a mathematically concise formulation from which some analytical insights can be obtained. It has been argued that because partial differential equations can describe polymorphic populations, results from such models are fundamentally different from those obtained using adaptive dynamics. In partial differential equation models, diversification manifests itself as pattern formation in phenotype distribution. More precisely, diversification occurs when phenotype distributions become multimodal, with the different modes corresponding to phenotypic clusters, or to species in sexual models. Such pattern formation occurs in partial differential equation models for competitive as well as for predator–prey interactions.Less
This chapter discusses partial differential equation models. Partial differential equations can describe the dynamics of phenotype distributions of polymorphic populations, and they allow for a mathematically concise formulation from which some analytical insights can be obtained. It has been argued that because partial differential equations can describe polymorphic populations, results from such models are fundamentally different from those obtained using adaptive dynamics. In partial differential equation models, diversification manifests itself as pattern formation in phenotype distribution. More precisely, diversification occurs when phenotype distributions become multimodal, with the different modes corresponding to phenotypic clusters, or to species in sexual models. Such pattern formation occurs in partial differential equation models for competitive as well as for predator–prey interactions.
Michael Doebeli
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128931
- eISBN:
- 9781400838936
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128931.003.0010
- Subject:
- Biology, Biodiversity / Conservation Biology
This concluding chapter argues that experimental evolution with microbes has emerged as a very attractive alternative to overcome the problem of long time scales in empirical studies of evolution. ...
More
This concluding chapter argues that experimental evolution with microbes has emerged as a very attractive alternative to overcome the problem of long time scales in empirical studies of evolution. This is exemplified by the long-term evolution experiments of Richard Lenski, whose experimental Escherichia coli lines have evolved for more than 40,000 generations to date. Lenski and his many collaborators convincingly argued that the diversified strains have coexisted over long time periods, and hence that this diversification represents a case of asexual speciation. The ecological mechanism for diversification in this case appears to be related to crossfeeding, a scenario in which one strain or species persists by scavenging on nutrients that accumulate in the environment as metabolic byproducts of the coexisting strain. With crossfeeding, polymorphisms can be maintained even in simple environments with a single limiting resource such as glucose. This is an excellent example of frequency-dependent selection, as the fitness of the crossfeeder depends on the presence or absence of the glucose specialist.Less
This concluding chapter argues that experimental evolution with microbes has emerged as a very attractive alternative to overcome the problem of long time scales in empirical studies of evolution. This is exemplified by the long-term evolution experiments of Richard Lenski, whose experimental Escherichia coli lines have evolved for more than 40,000 generations to date. Lenski and his many collaborators convincingly argued that the diversified strains have coexisted over long time periods, and hence that this diversification represents a case of asexual speciation. The ecological mechanism for diversification in this case appears to be related to crossfeeding, a scenario in which one strain or species persists by scavenging on nutrients that accumulate in the environment as metabolic byproducts of the coexisting strain. With crossfeeding, polymorphisms can be maintained even in simple environments with a single limiting resource such as glucose. This is an excellent example of frequency-dependent selection, as the fitness of the crossfeeder depends on the presence or absence of the glucose specialist.
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/9780691161549.003.0005
- Subject:
- Biology, Disease Ecology / Epidemiology
This chapter discusses coevolutionary dynamics of viruses and microbes. Virus mutation and host mutations occur rapidly, so much so that new virus and host mutants are expected to arise on timescales ...
More
This chapter discusses coevolutionary dynamics of viruses and microbes. Virus mutation and host mutations occur rapidly, so much so that new virus and host mutants are expected to arise on timescales similar to those for changes in total population. Host evolution to resistance can lead to virus extinction, but such extinction is not inevitable either in the lab or in the field. A single dominant host and virus type can, via a combination of mutation and selection, diversify into multiple virus and host types that coexist in one community. The interaction of multiple virus and host genotypes has fundamental effects on ecological dynamics. When multiple virus and host genotypes are present, their interactions can lead to novel ecological dynamics, such as apparently reversed predator–prey cycles. Moreover, the interactions of a single virus–host pair can lead to distinct modes of evolutionary dynamics, for example, fluctuating dynamics, arms races, and diversification.Less
This chapter discusses coevolutionary dynamics of viruses and microbes. Virus mutation and host mutations occur rapidly, so much so that new virus and host mutants are expected to arise on timescales similar to those for changes in total population. Host evolution to resistance can lead to virus extinction, but such extinction is not inevitable either in the lab or in the field. A single dominant host and virus type can, via a combination of mutation and selection, diversify into multiple virus and host types that coexist in one community. The interaction of multiple virus and host genotypes has fundamental effects on ecological dynamics. When multiple virus and host genotypes are present, their interactions can lead to novel ecological dynamics, such as apparently reversed predator–prey cycles. Moreover, the interactions of a single virus–host pair can lead to distinct modes of evolutionary dynamics, for example, fluctuating dynamics, arms races, and diversification.
Pat Willmer
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691128610
- eISBN:
- 9781400838943
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691128610.003.0004
- Subject:
- Biology, Ecology
This chapter examines the evolution of flowers, pollination, and plant diversity. There is good evidence for pollinator-mediated selection and appropriate trait heritability in flowers, and there are ...
More
This chapter examines the evolution of flowers, pollination, and plant diversity. There is good evidence for pollinator-mediated selection and appropriate trait heritability in flowers, and there are well-established mechanisms by which this could bring about floral change, reproductive isolation, and evolutionary divergence or specialization. The chapter first considers the origin and early evolution of flowers before discussing the diversification of angiosperms. It then explores the advantages of animal pollination and goes on to discuss the extent to which pollination may have contributed to floral variation, plant speciation, and plant diversification. In particular, it explains whether pollinators select for floral divergence and describes five ways in which floral divergence could arise by selection: adaptation to distinct niches, character displacement, adaptive “wandering,” character correlations, and genetic drift.Less
This chapter examines the evolution of flowers, pollination, and plant diversity. There is good evidence for pollinator-mediated selection and appropriate trait heritability in flowers, and there are well-established mechanisms by which this could bring about floral change, reproductive isolation, and evolutionary divergence or specialization. The chapter first considers the origin and early evolution of flowers before discussing the diversification of angiosperms. It then explores the advantages of animal pollination and goes on to discuss the extent to which pollination may have contributed to floral variation, plant speciation, and plant diversification. In particular, it explains whether pollinators select for floral divergence and describes five ways in which floral divergence could arise by selection: adaptation to distinct niches, character displacement, adaptive “wandering,” character correlations, and genetic drift.
A. Townsend Peterson, Jorge Soberón, Richard G. Pearson, Robert P. Anderson, Enrique Martínez-Meyer, Miguel Nakamura, and Miguel Bastos Araújo
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691136868
- eISBN:
- 9781400840670
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691136868.003.0015
- Subject:
- Biology, Ecology
This chapter examines how the process of ecological niche evolution and diversification helps us better understand ecology, biogeography, and biodiversity. It first considers how species respond to ...
More
This chapter examines how the process of ecological niche evolution and diversification helps us better understand ecology, biogeography, and biodiversity. It first considers how species respond to changes in the environmental substrate on which the niches are manifested before discussing the concept of niche conservatism as well as tests of conservatism in areas such as species invasions and comparison of the ecological niche requirements of sister–species pairs. It then explores how temporal change in niche dimensions occurs, how it can be studied, and what can be learned. It also describes some of the challenges associated with applications of ecological niche modeling in the realm of evolution and concludes by outlining future directions for research.Less
This chapter examines how the process of ecological niche evolution and diversification helps us better understand ecology, biogeography, and biodiversity. It first considers how species respond to changes in the environmental substrate on which the niches are manifested before discussing the concept of niche conservatism as well as tests of conservatism in areas such as species invasions and comparison of the ecological niche requirements of sister–species pairs. It then explores how temporal change in niche dimensions occurs, how it can be studied, and what can be learned. It also describes some of the challenges associated with applications of ecological niche modeling in the realm of evolution and concludes by outlining future directions for research.
Yannis M. Ioannides
- Published in print:
- 2012
- Published Online:
- October 2017
- ISBN:
- 9780691126852
- eISBN:
- 9781400845385
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691126852.003.0007
- Subject:
- Economics and Finance, Development, Growth, and Environmental
This chapter examines the consequences of urban specialization and diversification for urban structure and intercity trade. It first reviews the empirical evidence on urban specialization and ...
More
This chapter examines the consequences of urban specialization and diversification for urban structure and intercity trade. It first reviews the empirical evidence on urban specialization and diversification, including the results of Black and Henderson (2003), before discussing the simple economics of urban specialization. In particular, it considers the interrelationships between city geometry, productivity, and city size as well as equilibrium in a system of fully autarkic cities versus partly autarkic cities. The chapter proceeds by analyzing urban structure when intermediates and final goods are traded among cities, the effect of shipping costs on geography, and labor market frictions in the presence of Krugman diversification. Finally, it highlights some lessons that can be derived from the empirics of urban specialization and diversification in relation to intercity trade.Less
This chapter examines the consequences of urban specialization and diversification for urban structure and intercity trade. It first reviews the empirical evidence on urban specialization and diversification, including the results of Black and Henderson (2003), before discussing the simple economics of urban specialization. In particular, it considers the interrelationships between city geometry, productivity, and city size as well as equilibrium in a system of fully autarkic cities versus partly autarkic cities. The chapter proceeds by analyzing urban structure when intermediates and final goods are traded among cities, the effect of shipping costs on geography, and labor market frictions in the presence of Krugman diversification. Finally, it highlights some lessons that can be derived from the empirics of urban specialization and diversification in relation to intercity trade.
Jean Drèze and Amartya Sen
- Published in print:
- 1991
- Published Online:
- November 2003
- ISBN:
- 9780198283652
- eISBN:
- 9780191596193
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0198283652.003.0008
- Subject:
- Economics and Finance, Development, Growth, and Environmental
Some experiences in India and Africa are examined and lessons drawn from them. The authors show how the entitlement protection efforts of India since independence help explain the lack of famines, ...
More
Some experiences in India and Africa are examined and lessons drawn from them. The authors show how the entitlement protection efforts of India since independence help explain the lack of famines, and then focus on the 1970 Maharashtra drought. They analyse the success stories of Cape Verde, Kenya, Zimbabwe, and Botswana in Africa, referring again to the importance of entitlement protection systems. Special attention is given to the role of early intervention, private trade, diversification of economic activity and public distribution.Less
Some experiences in India and Africa are examined and lessons drawn from them. The authors show how the entitlement protection efforts of India since independence help explain the lack of famines, and then focus on the 1970 Maharashtra drought. They analyse the success stories of Cape Verde, Kenya, Zimbabwe, and Botswana in Africa, referring again to the importance of entitlement protection systems. Special attention is given to the role of early intervention, private trade, diversification of economic activity and public distribution.
