C. Neal Stewart
- Published in print:
- 2004
- Published Online:
- September 2007
- ISBN:
- 9780195157451
- eISBN:
- 9780199790388
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195157451.001.0001
- Subject:
- Biology, Biotechnology
From years prior to the release of the first commercial transgenic crop in 1995 to the present, many concerned activists, regulators, and scientists have questioned how genetic engineering might ...
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From years prior to the release of the first commercial transgenic crop in 1995 to the present, many concerned activists, regulators, and scientists have questioned how genetic engineering might impact the environment. No measurable negative environmental impacts have been observed for commercial genetically modified crops to date, even though several risks have been identified in experimental releases. Even so, none have approached doomsday scenarios posed by activists. The risks that have been extensively studied are gene flow from crops to weeds or crop landraces; side-effects of insecticidal transgenic proteins, such as accidental killing of monarch butterflies or beneficial insects; viral recombination; and transgene combinations. Close examination has uncovered no negative effects, but plenty of positive environmental impacts from growing crops engineered for insect resistance and herbicide resistance. Insect resistant cotton and corn kill only the insects that attempt to eat the crops and have saved several million gallons of chemical insecticide applications. Herbicide resistant soybean and corn have helped in soil conservation efforts since farmers do not have to use as much tillage to control weeds. In addition to these benefits, scientists are conducting research to produce genetically engineered plants to clean up toxins, produce plastics and biofuels, and perform other ecological services. The responsible use of genetic engineering is part of sustainable agriculture now and in the future.Less
From years prior to the release of the first commercial transgenic crop in 1995 to the present, many concerned activists, regulators, and scientists have questioned how genetic engineering might impact the environment. No measurable negative environmental impacts have been observed for commercial genetically modified crops to date, even though several risks have been identified in experimental releases. Even so, none have approached doomsday scenarios posed by activists. The risks that have been extensively studied are gene flow from crops to weeds or crop landraces; side-effects of insecticidal transgenic proteins, such as accidental killing of monarch butterflies or beneficial insects; viral recombination; and transgene combinations. Close examination has uncovered no negative effects, but plenty of positive environmental impacts from growing crops engineered for insect resistance and herbicide resistance. Insect resistant cotton and corn kill only the insects that attempt to eat the crops and have saved several million gallons of chemical insecticide applications. Herbicide resistant soybean and corn have helped in soil conservation efforts since farmers do not have to use as much tillage to control weeds. In addition to these benefits, scientists are conducting research to produce genetically engineered plants to clean up toxins, produce plastics and biofuels, and perform other ecological services. The responsible use of genetic engineering is part of sustainable agriculture now and in the future.
Rosalind James and Theresa L. Pitts-Singer (eds)
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780195316957
- eISBN:
- 9780199871575
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195316957.001.0001
- Subject:
- Biology, Animal Biology, Plant Sciences and Forestry
Bees play a vital role as pollinators for many agricultural crops. This book discusses the interplay between bees, agriculture, and the environment. Although honey bees are well recognized as ...
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Bees play a vital role as pollinators for many agricultural crops. This book discusses the interplay between bees, agriculture, and the environment. Although honey bees are well recognized as pollinators, managed bumble bees and solitary bees are also critical for the successful pollination of certain crops, while wild bees provide a free service. As bees liberally pass pollen from one plant to the next, they also impact the broader ecosystem, and not always to the benefit of humankind. Bees can enhance the unintentional spread of genes from genetically engineered plants, and may increase the spread of invasive weeds. Conversely, genetically engineered plants can impact pollinators, and invasive weeds can supply new sources of food for these insects. Bees' flower-visiting activities also can be exploited to spread biological control agents that help to control crop pests. Bee pollination is important for production of native plants used for restoration of wild lands. Managing bees for pollination is complex and must consider bee natural history, physiology, pathology, and behavior. Furthermore, transporting bees from native ranges to new areas for pollination services can be controversial, and should be done only after assuring that a non-native bee introduction will not disrupt the ecosystem. Even though bees are small, unobtrusive creatures, they play large roles in the ecosystem. The connection between bees and humankind is symbolic of a broader interconnection between humans and the natural world.Less
Bees play a vital role as pollinators for many agricultural crops. This book discusses the interplay between bees, agriculture, and the environment. Although honey bees are well recognized as pollinators, managed bumble bees and solitary bees are also critical for the successful pollination of certain crops, while wild bees provide a free service. As bees liberally pass pollen from one plant to the next, they also impact the broader ecosystem, and not always to the benefit of humankind. Bees can enhance the unintentional spread of genes from genetically engineered plants, and may increase the spread of invasive weeds. Conversely, genetically engineered plants can impact pollinators, and invasive weeds can supply new sources of food for these insects. Bees' flower-visiting activities also can be exploited to spread biological control agents that help to control crop pests. Bee pollination is important for production of native plants used for restoration of wild lands. Managing bees for pollination is complex and must consider bee natural history, physiology, pathology, and behavior. Furthermore, transporting bees from native ranges to new areas for pollination services can be controversial, and should be done only after assuring that a non-native bee introduction will not disrupt the ecosystem. Even though bees are small, unobtrusive creatures, they play large roles in the ecosystem. The connection between bees and humankind is symbolic of a broader interconnection between humans and the natural world.
James E. Cresswell
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780195316957
- eISBN:
- 9780199871575
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195316957.003.0011
- Subject:
- Biology, Animal Biology, Plant Sciences and Forestry
This chapter considers methods for quantifying the importance of bees in pollinating a crop and in producing field-to-field cross-pollination and gene flow. Simple theoretical models are presented ...
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This chapter considers methods for quantifying the importance of bees in pollinating a crop and in producing field-to-field cross-pollination and gene flow. Simple theoretical models are presented whose parameters identify key governing influences on bee pollination. The values of some parameters are known, particularly in systems involving honey bees and bumble bees, and their implications for the confinement of genetically-modified crops are discussed. Specific parameters whose values are unknown are identified as targets for future work.Less
This chapter considers methods for quantifying the importance of bees in pollinating a crop and in producing field-to-field cross-pollination and gene flow. Simple theoretical models are presented whose parameters identify key governing influences on bee pollination. The values of some parameters are known, particularly in systems involving honey bees and bumble bees, and their implications for the confinement of genetically-modified crops are discussed. Specific parameters whose values are unknown are identified as targets for future work.
Andrew P. Hendry
- Published in print:
- 2016
- Published Online:
- January 2018
- ISBN:
- 9780691145433
- eISBN:
- 9781400883080
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691145433.003.0005
- Subject:
- Biology, Ecology
This chapter looks at empirical methods for quantifying gene flow and inferring its role in adaptive divergence. An important point made therein is that gene flow can sometimes aid adaptation, such ...
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This chapter looks at empirical methods for quantifying gene flow and inferring its role in adaptive divergence. An important point made therein is that gene flow can sometimes aid adaptation, such as when it enhances the genetic variation on which selection acts. The key questions addressed with empirical data are divided into the potential negative versus positive effects. On the negative side, questions include to what extent gene flow constrains adaptive divergence among environments, and how the resulting maladaptation might cause population declines and limit species' ranges. On the positive side, questions include whether gene flow has a special benefit in the case of antagonistic coevolution, and whether it can save (rescue) populations that would otherwise go extinct.Less
This chapter looks at empirical methods for quantifying gene flow and inferring its role in adaptive divergence. An important point made therein is that gene flow can sometimes aid adaptation, such as when it enhances the genetic variation on which selection acts. The key questions addressed with empirical data are divided into the potential negative versus positive effects. On the negative side, questions include to what extent gene flow constrains adaptive divergence among environments, and how the resulting maladaptation might cause population declines and limit species' ranges. On the positive side, questions include whether gene flow has a special benefit in the case of antagonistic coevolution, and whether it can save (rescue) populations that would otherwise go extinct.
Antonio Fontdevila
- Published in print:
- 2011
- Published Online:
- September 2011
- ISBN:
- 9780199541379
- eISBN:
- 9780191728532
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199541379.003.0004
- Subject:
- Biology, Evolutionary Biology / Genetics, Developmental Biology
This chapter reports data, mainly from comparative genomics, which confirm a long-suspected high rate of interspecies gene flow due to hybridisation. It also reports the present interest in hybrids ...
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This chapter reports data, mainly from comparative genomics, which confirm a long-suspected high rate of interspecies gene flow due to hybridisation. It also reports the present interest in hybrids because of the recently documented hybrid origin of many species. However, sex is not the only mechanism to exchange genetic material among species. This chapter describes how horizontal gene transfer is a major mechanism that shapes the prokaryote genome, and a common mechanism in the eukaryotic world. Since reproductive isolation cannot often constitute an efficient barrier to preserve species identity, other mechanisms must be at work. This chapter argues that natural selection and genetic drift, acting at times in concert with reproductive isolation, are main factors that define the species borders in face of gene exchange among species. The chapter concludes that the ubiquity of gene flow and horizontal transfer may allow us to talk of the ‘web of life’.Less
This chapter reports data, mainly from comparative genomics, which confirm a long-suspected high rate of interspecies gene flow due to hybridisation. It also reports the present interest in hybrids because of the recently documented hybrid origin of many species. However, sex is not the only mechanism to exchange genetic material among species. This chapter describes how horizontal gene transfer is a major mechanism that shapes the prokaryote genome, and a common mechanism in the eukaryotic world. Since reproductive isolation cannot often constitute an efficient barrier to preserve species identity, other mechanisms must be at work. This chapter argues that natural selection and genetic drift, acting at times in concert with reproductive isolation, are main factors that define the species borders in face of gene exchange among species. The chapter concludes that the ubiquity of gene flow and horizontal transfer may allow us to talk of the ‘web of life’.
C. Neal Stewart
- Published in print:
- 2004
- Published Online:
- September 2007
- ISBN:
- 9780195157451
- eISBN:
- 9780199790388
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195157451.003.0005
- Subject:
- Biology, Biotechnology
In 2001, a group of researchers at the University of California-Berkeley published a report claiming that transgenes had moved from commercial corn to landrace corn in Oaxaca, Mexico. Transgenic corn ...
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In 2001, a group of researchers at the University of California-Berkeley published a report claiming that transgenes had moved from commercial corn to landrace corn in Oaxaca, Mexico. Transgenic corn had never been planted — at least legally — in Mexico, and so the researchers thought that it was an important scientific result with political implications. Mexican landrace corn had been propagated by indigenous farmers for centuries, and transgenes could be disruptive to the plant and the culture. The finding that transgenes were in landrace corn and parts of transgenes were hopping around the genome was hotly contested because of the flawed methodology used in the original study. Furthermore, the findings were never confirmed by any other researchers. In an unprecedented move, the journal editor announced that the paper should have never been published in the first place. This is one example of exaggerated claims that have encouraged the unnecessary controversy in agricultural biotechnology.Less
In 2001, a group of researchers at the University of California-Berkeley published a report claiming that transgenes had moved from commercial corn to landrace corn in Oaxaca, Mexico. Transgenic corn had never been planted — at least legally — in Mexico, and so the researchers thought that it was an important scientific result with political implications. Mexican landrace corn had been propagated by indigenous farmers for centuries, and transgenes could be disruptive to the plant and the culture. The finding that transgenes were in landrace corn and parts of transgenes were hopping around the genome was hotly contested because of the flawed methodology used in the original study. Furthermore, the findings were never confirmed by any other researchers. In an unprecedented move, the journal editor announced that the paper should have never been published in the first place. This is one example of exaggerated claims that have encouraged the unnecessary controversy in agricultural biotechnology.
Jacob Höglund
- Published in print:
- 2009
- Published Online:
- May 2009
- ISBN:
- 9780199214211
- eISBN:
- 9780191706660
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199214211.003.0004
- Subject:
- Biology, Biodiversity / Conservation Biology, Evolutionary Biology / Genetics
This chapter reviews the genetic consequences of environmental change. These changes are often so rapid that contemporary populations are often not found in genetic equilibrium. Furthermore, ...
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This chapter reviews the genetic consequences of environmental change. These changes are often so rapid that contemporary populations are often not found in genetic equilibrium. Furthermore, human-induced habitat fragmentation often results in a complex mosaic of remaining populations that differ in size and connectivity. A number of tools have been developed to detect population structure, gene flow, and evolution in such complex situations. The chapter provides evidence of rapid evolutionary responses in many organisms to changes in the environment. Such changes may be induced by a multitude of factors, including habitat loss and fragmentation, hindrances to dispersal and hence gene flow, climatic changes, and introduction of invasive species.Less
This chapter reviews the genetic consequences of environmental change. These changes are often so rapid that contemporary populations are often not found in genetic equilibrium. Furthermore, human-induced habitat fragmentation often results in a complex mosaic of remaining populations that differ in size and connectivity. A number of tools have been developed to detect population structure, gene flow, and evolution in such complex situations. The chapter provides evidence of rapid evolutionary responses in many organisms to changes in the environment. Such changes may be induced by a multitude of factors, including habitat loss and fragmentation, hindrances to dispersal and hence gene flow, climatic changes, and introduction of invasive species.
Patrik Nosil
- Published in print:
- 2012
- Published Online:
- May 2015
- ISBN:
- 9780199587100
- eISBN:
- 9780191810107
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:osobl/9780199587100.003.0006
- Subject:
- Biology, Evolutionary Biology / Genetics
This chapter focuses on the geographic component of ecological speciation. It begins by giving different definitions of the geography of speciation and then studies the effects of geography on the ...
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This chapter focuses on the geographic component of ecological speciation. It begins by giving different definitions of the geography of speciation and then studies the effects of geography on the sources of divergent selection. It considers how geographic contact between populations might constrain or promote ecological speciation, and how speciation can involve multiple geographic modes of divergence. It also assesses the empirical problem of detecting gene flow, through consideration of comparative geographic, coalescent-based, and genomic approaches. It concludes with a consideration of speciation along continuous environmental gradients versus between discrete patches and the unresolved issue of the spatial scale of speciation.Less
This chapter focuses on the geographic component of ecological speciation. It begins by giving different definitions of the geography of speciation and then studies the effects of geography on the sources of divergent selection. It considers how geographic contact between populations might constrain or promote ecological speciation, and how speciation can involve multiple geographic modes of divergence. It also assesses the empirical problem of detecting gene flow, through consideration of comparative geographic, coalescent-based, and genomic approaches. It concludes with a consideration of speciation along continuous environmental gradients versus between discrete patches and the unresolved issue of the spatial scale of speciation.
Geoffrey E. Hill
- Published in print:
- 2019
- Published Online:
- June 2019
- ISBN:
- 9780198818250
- eISBN:
- 9780191859465
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198818250.003.0007
- Subject:
- Biology, Ecology, Evolutionary Biology / Genetics
Current models of speciation assume that species arise when nuclear genotypes diverge following the disruption of gene flow between populations. This chapter explores the idea that speciation is ...
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Current models of speciation assume that species arise when nuclear genotypes diverge following the disruption of gene flow between populations. This chapter explores the idea that speciation is specifically the result of divergence in coadapted mitonuclear gene complexes with divergence of most nuclear genes playing little or no role in speciation. To maintain mitonuclear coadaptation, nuclear genes must coevolve with rapidly changing mitochondrial genes. According to the mitonuclear compatibility concept of species, mitonuclear coevolution in isolated populations leads to speciation because population-specific mitonuclear coadaptations create between-population mitonuclear incompatibilities and hence barriers to gene flow between populations. In addition, selection for adaptive divergence of products of mitochondrial genes can lead to rapid fixation of novel mitochondrial genotypes between populations and consequently to disruption in gene flow between populations as the initiating step in animal speciation. The chapter considers the evidence for the involvement of mitonuclear compatibility in the process of speciation and the implications for this new concept of speciation and species.Less
Current models of speciation assume that species arise when nuclear genotypes diverge following the disruption of gene flow between populations. This chapter explores the idea that speciation is specifically the result of divergence in coadapted mitonuclear gene complexes with divergence of most nuclear genes playing little or no role in speciation. To maintain mitonuclear coadaptation, nuclear genes must coevolve with rapidly changing mitochondrial genes. According to the mitonuclear compatibility concept of species, mitonuclear coevolution in isolated populations leads to speciation because population-specific mitonuclear coadaptations create between-population mitonuclear incompatibilities and hence barriers to gene flow between populations. In addition, selection for adaptive divergence of products of mitochondrial genes can lead to rapid fixation of novel mitochondrial genotypes between populations and consequently to disruption in gene flow between populations as the initiating step in animal speciation. The chapter considers the evidence for the involvement of mitonuclear compatibility in the process of speciation and the implications for this new concept of speciation and species.
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/9780691128610.003.0022
- Subject:
- Biology, Ecology
This chapter examines competition in the context of pollination ecology. Competition is typically treated from the perspective of the plants, but it is also likely to occur among and between the ...
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This chapter examines competition in the context of pollination ecology. Competition is typically treated from the perspective of the plants, but it is also likely to occur among and between the pollinators. Furthermore, competition can occur at various levels—as a structuring factor in communities, as a selective force on an individual plant’s phenology, morphology, or rewards, and at a genetic level structuring competition for pollens between males, and female choice between possible mates. The chapter first considers several types of of competition in pollination ecology, potential outcomes of competition, and competition between pollinators before discussing how selection reduces intraspecific competition among plants and competition among pollinators. It also explores paternity, maternity, and gene flow in coflowering communities, focusing in particular on male competition and female choice, along with gene flow via pollen dispersal and seed dispersal.Less
This chapter examines competition in the context of pollination ecology. Competition is typically treated from the perspective of the plants, but it is also likely to occur among and between the pollinators. Furthermore, competition can occur at various levels—as a structuring factor in communities, as a selective force on an individual plant’s phenology, morphology, or rewards, and at a genetic level structuring competition for pollens between males, and female choice between possible mates. The chapter first considers several types of of competition in pollination ecology, potential outcomes of competition, and competition between pollinators before discussing how selection reduces intraspecific competition among plants and competition among pollinators. It also explores paternity, maternity, and gene flow in coflowering communities, focusing in particular on male competition and female choice, along with gene flow via pollen dispersal and seed dispersal.
Patrik Nosil
- Published in print:
- 2012
- Published Online:
- May 2015
- ISBN:
- 9780199587100
- eISBN:
- 9780191810107
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:osobl/9780199587100.001.0001
- Subject:
- Biology, Evolutionary Biology / Genetics
The origin of biological diversity, via the formation of new species, can be inextricably linked to adaptation to the ecological environment. Specifically, ecological processes are central to the ...
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The origin of biological diversity, via the formation of new species, can be inextricably linked to adaptation to the ecological environment. Specifically, ecological processes are central to the formation of new species when barriers to gene flow (reproductive isolation) evolve between populations as a result of ecologically based divergent natural selection. This process of ‘ecological speciation’ has seen a large body of focused research in the last ten-fifteen years, and a review and synthesis of the theoretical and empirical literature is now timely. The book begins by clarifying what ecological speciation is, its alternatives, and the predictions that can be used to test for it. It then reviews the three components of ecological speciation and discusses the geography and genomic basis of the process. A final chapter highlights future research directions, describing the approaches and experiments which might be used to conduct that future work. The ecological and genetic literature is integrated throughout the text with the goal of shedding new insight into the speciation process, particularly when the empirical data is then further integrated with theory.Less
The origin of biological diversity, via the formation of new species, can be inextricably linked to adaptation to the ecological environment. Specifically, ecological processes are central to the formation of new species when barriers to gene flow (reproductive isolation) evolve between populations as a result of ecologically based divergent natural selection. This process of ‘ecological speciation’ has seen a large body of focused research in the last ten-fifteen years, and a review and synthesis of the theoretical and empirical literature is now timely. The book begins by clarifying what ecological speciation is, its alternatives, and the predictions that can be used to test for it. It then reviews the three components of ecological speciation and discusses the geography and genomic basis of the process. A final chapter highlights future research directions, describing the approaches and experiments which might be used to conduct that future work. The ecological and genetic literature is integrated throughout the text with the goal of shedding new insight into the speciation process, particularly when the empirical data is then further integrated with theory.
Florian M. Steiner, Ross H. Crozier, and Birgit C. Schlick‐Steiner
- Published in print:
- 2009
- Published Online:
- February 2010
- ISBN:
- 9780199544639
- eISBN:
- 9780191720192
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199544639.003.0010
- Subject:
- Biology, Ecology, Animal Biology
Ant colony structure is a colony's caste, demographic, genealogical, and spatial make‐up. Characters of colony structure include the number and identity of reproductives, worker task allocation, and ...
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Ant colony structure is a colony's caste, demographic, genealogical, and spatial make‐up. Characters of colony structure include the number and identity of reproductives, worker task allocation, and the nest number and architecture. A diversity of factors affect character states: genetics and gene flow, morphology, signal chemistry, nutrition, habitat, pathogen and parasite load, cooperation and conflict in the colony, colony age, and chance. Colony structure, in turn, has consequences for the colony, the population, the ant community, other organisms, and the abiotic environment. The formation of supercolonies represents a paradox in colony structure; reproductive altruism among unrelated individuals is not explicable by evolutionary theory that involves relatedness. Future work requires a more holistic approach to draw more universal conclusions on colony structure.Less
Ant colony structure is a colony's caste, demographic, genealogical, and spatial make‐up. Characters of colony structure include the number and identity of reproductives, worker task allocation, and the nest number and architecture. A diversity of factors affect character states: genetics and gene flow, morphology, signal chemistry, nutrition, habitat, pathogen and parasite load, cooperation and conflict in the colony, colony age, and chance. Colony structure, in turn, has consequences for the colony, the population, the ant community, other organisms, and the abiotic environment. The formation of supercolonies represents a paradox in colony structure; reproductive altruism among unrelated individuals is not explicable by evolutionary theory that involves relatedness. Future work requires a more holistic approach to draw more universal conclusions on colony structure.
Norman A. Johnson
- Published in print:
- 2007
- Published Online:
- September 2007
- ISBN:
- 9780195306750
- eISBN:
- 9780199790203
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195306750.003.0007
- Subject:
- Biology, Evolutionary Biology / Genetics
How close were the Neanderthals to modern humans? Are Neanderthal genes in our gene pool? This chapter explores recent studies analyzing the DNA from Neanderthal fossils to provide a framework to ...
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How close were the Neanderthals to modern humans? Are Neanderthal genes in our gene pool? This chapter explores recent studies analyzing the DNA from Neanderthal fossils to provide a framework to address these and related questions. Based on these fossil DNA studies, it appears that little if any gene flow occurred between Neanderthals despite many centuries of these groups living in proximity. For this reason, Neanderthals and modern humans are likely separate species.Less
How close were the Neanderthals to modern humans? Are Neanderthal genes in our gene pool? This chapter explores recent studies analyzing the DNA from Neanderthal fossils to provide a framework to address these and related questions. Based on these fossil DNA studies, it appears that little if any gene flow occurred between Neanderthals despite many centuries of these groups living in proximity. For this reason, Neanderthals and modern humans are likely separate species.
Michael L. Arnold
- Published in print:
- 2007
- Published Online:
- April 2010
- ISBN:
- 9780199229031
- eISBN:
- 9780191728266
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199229031.003.0009
- Subject:
- Biology, Evolutionary Biology / Genetics
This chapter reviews findings relating to the effect of genetic exchange on the evolution of the human lineage and lineages of organisms with which we interact (e.g. disease vectors, food sources). ...
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This chapter reviews findings relating to the effect of genetic exchange on the evolution of the human lineage and lineages of organisms with which we interact (e.g. disease vectors, food sources). It considers fossil and genetic data that suggest gene flow between various archaic taxa, and between archaic taxa and anatomically modern Homo. It shows that the disastrous effects of natural hybridization and lateral gene transfer in disease and disease-vector evolution. The chapter also considers the highly beneficial results from the same processes in producing food products, drugs, and even clothing. It concludes with a discussion demonstrating that Homo sapiens has played an active role in producing new strands of the web of life.Less
This chapter reviews findings relating to the effect of genetic exchange on the evolution of the human lineage and lineages of organisms with which we interact (e.g. disease vectors, food sources). It considers fossil and genetic data that suggest gene flow between various archaic taxa, and between archaic taxa and anatomically modern Homo. It shows that the disastrous effects of natural hybridization and lateral gene transfer in disease and disease-vector evolution. The chapter also considers the highly beneficial results from the same processes in producing food products, drugs, and even clothing. It concludes with a discussion demonstrating that Homo sapiens has played an active role in producing new strands of the web of life.
Dale H. Clayton, Sarah E. Bush, and Kevin P. Johnson
- Published in print:
- 2015
- Published Online:
- May 2016
- ISBN:
- 9780226302133
- eISBN:
- 9780226302300
- Item type:
- chapter
- Publisher:
- University of Chicago Press
- DOI:
- 10.7208/chicago/9780226302300.003.0008
- Subject:
- Biology, Evolutionary Biology / Genetics
Populations are seldom uniform; they tend to be subdivided, with gene frequencies unevenly distributed across landscapes. In this chapter, determinants of population structure in parasites are first ...
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Populations are seldom uniform; they tend to be subdivided, with gene frequencies unevenly distributed across landscapes. In this chapter, determinants of population structure in parasites are first reviewed. Lice turn out to be excellent models for studies of population structure. Population genetic structure arises largely because of limitations to dispersal and gene flow. Population variation in parasites is influenced by the rate of parasite dispersal at three scales: dispersal among host individuals, among host populations, and among host species. If most dispersal consists of vertical transmission from parent hosts to their offspring, then parasites living on individual hosts and their progeny will accumulate genetic differences, contributing to population genetic structure. If horizontal transmission is common, however, it will tend to erode population genetic structure among host individuals. It is essential to have information regarding the dispersal ecology of parasites in order to interpret parasite population structure.Less
Populations are seldom uniform; they tend to be subdivided, with gene frequencies unevenly distributed across landscapes. In this chapter, determinants of population structure in parasites are first reviewed. Lice turn out to be excellent models for studies of population structure. Population genetic structure arises largely because of limitations to dispersal and gene flow. Population variation in parasites is influenced by the rate of parasite dispersal at three scales: dispersal among host individuals, among host populations, and among host species. If most dispersal consists of vertical transmission from parent hosts to their offspring, then parasites living on individual hosts and their progeny will accumulate genetic differences, contributing to population genetic structure. If horizontal transmission is common, however, it will tend to erode population genetic structure among host individuals. It is essential to have information regarding the dispersal ecology of parasites in order to interpret parasite population structure.
Michael L. Arnold
- Published in print:
- 2007
- Published Online:
- April 2010
- ISBN:
- 9780199229031
- eISBN:
- 9780191728266
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199229031.003.0010
- Subject:
- Biology, Evolutionary Biology / Genetics
This chapter begins by reflecting upon the major theme of this book: that genetic exchange is pervasive across all biological lineages. It discusses the implications of this regarding the ...
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This chapter begins by reflecting upon the major theme of this book: that genetic exchange is pervasive across all biological lineages. It discusses the implications of this regarding the tree-of-life and web-of-life concepts. Research directions that will benefit our understanding of the role of genetic exchange in evolution are also discussed. Some of these, including the use of genomic information to discern web processes, are gaining momentum with the appearance of many new data-sets. Others, such as studies that investigate the role of ecological setting on the outcome of genetic exchange, are rare, yet they represent another Golden Fleece because of their potential to yield new insights of major importance.Less
This chapter begins by reflecting upon the major theme of this book: that genetic exchange is pervasive across all biological lineages. It discusses the implications of this regarding the tree-of-life and web-of-life concepts. Research directions that will benefit our understanding of the role of genetic exchange in evolution are also discussed. Some of these, including the use of genomic information to discern web processes, are gaining momentum with the appearance of many new data-sets. Others, such as studies that investigate the role of ecological setting on the outcome of genetic exchange, are rare, yet they represent another Golden Fleece because of their potential to yield new insights of major importance.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2017
- Published Online:
- September 2017
- ISBN:
- 9780198783398
- eISBN:
- 9780191826313
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783398.003.0012
- Subject:
- Biology, Biodiversity / Conservation Biology
When the decision is made to augment gene flow into an isolated population, managers must decide how to augment gene flow, when to start, from where to take the individuals or gametes to be added, ...
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When the decision is made to augment gene flow into an isolated population, managers must decide how to augment gene flow, when to start, from where to take the individuals or gametes to be added, how many, which individuals, how often and when to cease. Even without detailed genetic data, sound genetic management strategies for augmenting gene flow can be instituted by considering population genetics theory, and/or computer simulations. When detailed data are lacking, moving (translocating) some individuals into isolated inbred population fragments is better than moving none, as long as the risk of outbreeding depression is low.Less
When the decision is made to augment gene flow into an isolated population, managers must decide how to augment gene flow, when to start, from where to take the individuals or gametes to be added, how many, which individuals, how often and when to cease. Even without detailed genetic data, sound genetic management strategies for augmenting gene flow can be instituted by considering population genetics theory, and/or computer simulations. When detailed data are lacking, moving (translocating) some individuals into isolated inbred population fragments is better than moving none, as long as the risk of outbreeding depression is low.
Alan G. Fix
- Published in print:
- 2011
- Published Online:
- January 2012
- ISBN:
- 9780813036076
- eISBN:
- 9780813041780
- Item type:
- chapter
- Publisher:
- University Press of Florida
- DOI:
- 10.5744/florida/9780813036076.003.0013
- Subject:
- Society and Culture, Social Groups
Migration and its consequence, gene flow, have been a major force affecting the frequency, spatial pattern, and spread of genes in human populations. Methodologies to document or infer local and ...
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Migration and its consequence, gene flow, have been a major force affecting the frequency, spatial pattern, and spread of genes in human populations. Methodologies to document or infer local and regional movement include such ethnographic techniques as migration histories and genealogies, and ethnohistory. Anthropological geneticists also attempt to infer larger scale movement in past times by using both “classical” and molecular gene distributions. Inference based on genetic markers, however, often is contentious since alternative explanations are hard to exclude. This chapter employs an extended case study of a population, the Semai Senoi of Peninsular Malaysia, to examine and evaluate migration from the recent and local to the long-term in the Southeast Asian region.Less
Migration and its consequence, gene flow, have been a major force affecting the frequency, spatial pattern, and spread of genes in human populations. Methodologies to document or infer local and regional movement include such ethnographic techniques as migration histories and genealogies, and ethnohistory. Anthropological geneticists also attempt to infer larger scale movement in past times by using both “classical” and molecular gene distributions. Inference based on genetic markers, however, often is contentious since alternative explanations are hard to exclude. This chapter employs an extended case study of a population, the Semai Senoi of Peninsular Malaysia, to examine and evaluate migration from the recent and local to the long-term in the Southeast Asian region.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2017
- Published Online:
- September 2017
- ISBN:
- 9780198783398
- eISBN:
- 9780191826313
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783398.001.0001
- Subject:
- Biology, Biodiversity / Conservation Biology
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease and fragmentation ...
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The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease and fragmentation increases, loss of genetic diversity reduces their ability to adapt to changes in the environment, with inbreeding and reduced fitness inevitable consequences for many species. Many small isolated populations are going extinct unnecessarily. In many cases, such populations can be genetically rescued by gene flow into them from another population within the species, but this is very rarely done. This novel and authoritative book addresses the issues involved in genetic management of fragmented animal and plant populations, including inbreeding depression, loss of genetic diversity and elevated extinction risk in small isolated populations, augmentation of gene flow, genetic rescue, causes of outbreeding depression and predicting its occurrence, desirability and implementation of genetic translocations to cope with climate change, and defining and diagnosing species for conservation purposes.Less
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease and fragmentation increases, loss of genetic diversity reduces their ability to adapt to changes in the environment, with inbreeding and reduced fitness inevitable consequences for many species. Many small isolated populations are going extinct unnecessarily. In many cases, such populations can be genetically rescued by gene flow into them from another population within the species, but this is very rarely done. This novel and authoritative book addresses the issues involved in genetic management of fragmented animal and plant populations, including inbreeding depression, loss of genetic diversity and elevated extinction risk in small isolated populations, augmentation of gene flow, genetic rescue, causes of outbreeding depression and predicting its occurrence, desirability and implementation of genetic translocations to cope with climate change, and defining and diagnosing species for conservation purposes.
Andrew P. Hendry
- Published in print:
- 2016
- Published Online:
- January 2018
- ISBN:
- 9780691145433
- eISBN:
- 9781400883080
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691145433.003.0006
- Subject:
- Biology, Ecology
This chapter examines how populations in different environments can fall at different stages along a continuum of progress toward ecological speciation. It traces how variation can be used to infer ...
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This chapter examines how populations in different environments can fall at different stages along a continuum of progress toward ecological speciation. It traces how variation can be used to infer ecological speciation through either of two general approaches: (1) integrated signatures of reproductive isolation based on measures of gene flow, and (2) confirmation of the ecological basis of reproductive barriers. The chapter also addresses the rapidity of ecological speciation (rapid speciation), at what point progress toward ecological speciation becomes irreversible (speciation reversal), to what extent ecological speciation is driven by competitive (adaptive speciation) or reproductive (reinforcement) interactions, and how many traits (magic traits) and selective pressures (dimensionality) are involved.Less
This chapter examines how populations in different environments can fall at different stages along a continuum of progress toward ecological speciation. It traces how variation can be used to infer ecological speciation through either of two general approaches: (1) integrated signatures of reproductive isolation based on measures of gene flow, and (2) confirmation of the ecological basis of reproductive barriers. The chapter also addresses the rapidity of ecological speciation (rapid speciation), at what point progress toward ecological speciation becomes irreversible (speciation reversal), to what extent ecological speciation is driven by competitive (adaptive speciation) or reproductive (reinforcement) interactions, and how many traits (magic traits) and selective pressures (dimensionality) are involved.
