John C. Avise
- Published in print:
- 2008
- Published Online:
- January 2009
- ISBN:
- 9780195369670
- eISBN:
- 9780199871063
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195369670.003.0002
- Subject:
- Biology, Evolutionary Biology / Genetics
Sexual reproduction is the antithesis of clonality because genes that are faithfully copied during asexual replication are genetically scrambled (recombined) during the sexual processes of meiosis ...
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Sexual reproduction is the antithesis of clonality because genes that are faithfully copied during asexual replication are genetically scrambled (recombined) during the sexual processes of meiosis and fertilization. Sex has long been an evolutionary enigma because it appears at face value to entail several fitness costs and risks in the short term whereas its potential benefits would seem to be rather diffuse and postponed. This chapter reviews the diverse explanations for recombinational sex, ranging from the level of molecular genetics to the echelons of short-term ecology and long-term evolution. It thus sets the stage for the book's extended thesis that any attempt to understand the adaptive significance of sex is likely to be facilitated by analyzing clonal systems, and vice versa.Less
Sexual reproduction is the antithesis of clonality because genes that are faithfully copied during asexual replication are genetically scrambled (recombined) during the sexual processes of meiosis and fertilization. Sex has long been an evolutionary enigma because it appears at face value to entail several fitness costs and risks in the short term whereas its potential benefits would seem to be rather diffuse and postponed. This chapter reviews the diverse explanations for recombinational sex, ranging from the level of molecular genetics to the echelons of short-term ecology and long-term evolution. It thus sets the stage for the book's extended thesis that any attempt to understand the adaptive significance of sex is likely to be facilitated by analyzing clonal systems, and vice versa.
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/9780691128931.003.0004
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter examines evolutionary branching in sexual populations. As sexual populations converge to what would be a branching point in clonal models, splitting obviously becomes a problem, because ...
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This chapter examines evolutionary branching in sexual populations. As sexual populations converge to what would be a branching point in clonal models, splitting obviously becomes a problem, because mating between different marginal phenotypes generally creates intermediate phenotypes. Through segregation and recombination, sexual reproduction can prevent the establishment of diverging phenotypic clusters in randomly mating populations. To allow for a phenotypic split, mating needs to be assortative with respect to the ecological trait that is under disruptive selection. Thus, the question of evolutionary branching in sexual populations, that is, of adaptive speciation, is intimately tied to questions about the evolution of assortative mating. If evolutionary branching occurs in sexual populations due to the presence of assortative mating mechanisms, the diverging phenotypic clusters will show prezygotic reproductive isolation at least to some extent, and hence they can be viewed as representing incipient species.Less
This chapter examines evolutionary branching in sexual populations. As sexual populations converge to what would be a branching point in clonal models, splitting obviously becomes a problem, because mating between different marginal phenotypes generally creates intermediate phenotypes. Through segregation and recombination, sexual reproduction can prevent the establishment of diverging phenotypic clusters in randomly mating populations. To allow for a phenotypic split, mating needs to be assortative with respect to the ecological trait that is under disruptive selection. Thus, the question of evolutionary branching in sexual populations, that is, of adaptive speciation, is intimately tied to questions about the evolution of assortative mating. If evolutionary branching occurs in sexual populations due to the presence of assortative mating mechanisms, the diverging phenotypic clusters will show prezygotic reproductive isolation at least to some extent, and hence they can be viewed as representing incipient species.
Beth Linker and Whitney E. Laemmli
- Published in print:
- 2017
- Published Online:
- September 2017
- ISBN:
- 9780190458997
- eISBN:
- 9780190459024
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780190458997.003.0007
- Subject:
- Social Work, Health and Mental Health
At the conclusion of World War II, more than 600,000 men returned to the United States with long-term disabilities, profoundly destabilizing male sexuality in America. This chapter excavates the ...
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At the conclusion of World War II, more than 600,000 men returned to the United States with long-term disabilities, profoundly destabilizing male sexuality in America. This chapter excavates the contours of that change and its attendant anxieties in order to broaden scholarly interpretations of sexuality in the postwar period. Ultimately, the chapter shows that, although sexual reproduction is often coded female and sexual performance male, such a popularly held binary does not hold true when it comes to the history of paraplegic World War II veterans. To these veterans, and to the medical men who treated them, sexual reproduction became the ultimate signifier of remasculinization.Less
At the conclusion of World War II, more than 600,000 men returned to the United States with long-term disabilities, profoundly destabilizing male sexuality in America. This chapter excavates the contours of that change and its attendant anxieties in order to broaden scholarly interpretations of sexuality in the postwar period. Ultimately, the chapter shows that, although sexual reproduction is often coded female and sexual performance male, such a popularly held binary does not hold true when it comes to the history of paraplegic World War II veterans. To these veterans, and to the medical men who treated them, sexual reproduction became the ultimate signifier of remasculinization.
Leo W. Beukeboom and Nicolas Perrin
- Published in print:
- 2014
- Published Online:
- August 2014
- ISBN:
- 9780199657148
- eISBN:
- 9780191748103
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199657148.001.0001
- Subject:
- Biology, Evolutionary Biology / Genetics
Sexual reproduction is a fundamental aspect of life. It is defined by the occurrence of meiosis and the fusion of two gametes of different sexes or mating types. Genetic mechanisms for the ...
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Sexual reproduction is a fundamental aspect of life. It is defined by the occurrence of meiosis and the fusion of two gametes of different sexes or mating types. Genetic mechanisms for the determination and differentiation of the two sexes are diverse and evolutionary labile. This book synthesizes the contemporary literature on patterns and processes of sex determination evolution. The first chapter introduces definitions and concepts of sexual reproduction. Chapter 2 provides a comprehensive classification of sex-determination systems and describes the diversity of sexual cycles across eukaryote lineages, from excavates to mammals. Subsequent chapters detail the molecular mechanisms and quantitative genetics of sex determination (Chapters 3 and 4), examine the processes of sex-chromosome evolution (Chapter 5), and discuss life-history consequences of sex-determination systems (Chapter 6). The final chapter addresses the evolutionary processes responsible for the diversity and turnover in sex determination (Chapter 7). The book provides an overview of different sex-determination systems and details of its molecular regulation in fungi, plants, and animals, many of which are covered in separate text boxes and figures. It is argued that sex determination and primary sex differentiation cannot be regarded as separate processes and that the traditional dichotomous view of genotypic (GSD) and environmental (ESD) sex determination is no longer accurate. Ample documentation is provided about how sex determination affects, and is affected by, various forms of sexual conflict, sexual selection, and speciation. The book makes clear that sex-determination evolution will remain a highly dynamic field of research in the future.Less
Sexual reproduction is a fundamental aspect of life. It is defined by the occurrence of meiosis and the fusion of two gametes of different sexes or mating types. Genetic mechanisms for the determination and differentiation of the two sexes are diverse and evolutionary labile. This book synthesizes the contemporary literature on patterns and processes of sex determination evolution. The first chapter introduces definitions and concepts of sexual reproduction. Chapter 2 provides a comprehensive classification of sex-determination systems and describes the diversity of sexual cycles across eukaryote lineages, from excavates to mammals. Subsequent chapters detail the molecular mechanisms and quantitative genetics of sex determination (Chapters 3 and 4), examine the processes of sex-chromosome evolution (Chapter 5), and discuss life-history consequences of sex-determination systems (Chapter 6). The final chapter addresses the evolutionary processes responsible for the diversity and turnover in sex determination (Chapter 7). The book provides an overview of different sex-determination systems and details of its molecular regulation in fungi, plants, and animals, many of which are covered in separate text boxes and figures. It is argued that sex determination and primary sex differentiation cannot be regarded as separate processes and that the traditional dichotomous view of genotypic (GSD) and environmental (ESD) sex determination is no longer accurate. Ample documentation is provided about how sex determination affects, and is affected by, various forms of sexual conflict, sexual selection, and speciation. The book makes clear that sex-determination evolution will remain a highly dynamic field of research in the future.
Theodore (ed.)
- Published in print:
- 2009
- Published Online:
- March 2012
- ISBN:
- 9780520247666
- eISBN:
- 9780520944473
- Item type:
- book
- Publisher:
- University of California Press
- DOI:
- 10.1525/california/9780520247666.001.0001
- Subject:
- Biology, Evolutionary Biology / Genetics
Experimental approaches to evolution provide indisputable evidence of evolution by directly observing the process at work. Experimental evolution deliberately duplicates evolutionary ...
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Experimental approaches to evolution provide indisputable evidence of evolution by directly observing the process at work. Experimental evolution deliberately duplicates evolutionary processes—forcing life histories to evolve, producing adaptations to stressful environmental conditions, and generating lineage splitting to create incipient species. This book summarizes studies in experimental evolution, outlining current techniques and applications, and presenting the field's full range of research—from selection in the laboratory to the manipulation of populations in the wild. It provides work on such key biological problems as the evolution of Darwinian fitness, sexual reproduction, life history, athletic performance, and learning.Less
Experimental approaches to evolution provide indisputable evidence of evolution by directly observing the process at work. Experimental evolution deliberately duplicates evolutionary processes—forcing life histories to evolve, producing adaptations to stressful environmental conditions, and generating lineage splitting to create incipient species. This book summarizes studies in experimental evolution, outlining current techniques and applications, and presenting the field's full range of research—from selection in the laboratory to the manipulation of populations in the wild. It provides work on such key biological problems as the evolution of Darwinian fitness, sexual reproduction, life history, athletic performance, and learning.
Andrew F. G. Bourke
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199231157
- eISBN:
- 9780191774553
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199231157.003.0004
- Subject:
- Biology, Evolutionary Biology / Genetics
Pathways of social group formation are poorly known for the origin of the eukaryotic cell, sexual reproduction, and many interspecific mutualisms. In the origin of multicellularity and eusociality, ...
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Pathways of social group formation are poorly known for the origin of the eukaryotic cell, sexual reproduction, and many interspecific mutualisms. In the origin of multicellularity and eusociality, social group formation has usually occurred via a subsocial pathway (association of parents and offspring), with a semisocial pathway (association of same-generation organisms) occurring occasionally. The essential genetic condition for social group formation in groups exhibiting altruism is that relatedness should be positive – a prediction overwhelmingly supported by available evidence in the case of both the origin of multicellularity and the origin of eusociality. Non-genetic factors (ecological or synergistic) facilitate social group formation by increasing the benefits of grouping and the costs of living singly. Ecological factors promoting the formation of multicellular organisms and eusocial societies include environmental stresses and predator pressure. A major synergistic factor promoting the formation of multicellular organisms, eusocial societies, and interspecific mutualisms is division of labour.Less
Pathways of social group formation are poorly known for the origin of the eukaryotic cell, sexual reproduction, and many interspecific mutualisms. In the origin of multicellularity and eusociality, social group formation has usually occurred via a subsocial pathway (association of parents and offspring), with a semisocial pathway (association of same-generation organisms) occurring occasionally. The essential genetic condition for social group formation in groups exhibiting altruism is that relatedness should be positive – a prediction overwhelmingly supported by available evidence in the case of both the origin of multicellularity and the origin of eusociality. Non-genetic factors (ecological or synergistic) facilitate social group formation by increasing the benefits of grouping and the costs of living singly. Ecological factors promoting the formation of multicellular organisms and eusocial societies include environmental stresses and predator pressure. A major synergistic factor promoting the formation of multicellular organisms, eusocial societies, and interspecific mutualisms is division of labour.
Dennis Austin Britton
- Published in print:
- 2014
- Published Online:
- September 2014
- ISBN:
- 9780823257140
- eISBN:
- 9780823261482
- Item type:
- chapter
- Publisher:
- Fordham University Press
- DOI:
- 10.5422/fordham/9780823257140.003.0006
- Subject:
- Literature, European Literature
Whereas numerous infidel women convert to Christianity on the early modern English stage, relatively few infidel men convert. Chapter 5 explores the interplay of race, gender, and salvation in ...
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Whereas numerous infidel women convert to Christianity on the early modern English stage, relatively few infidel men convert. Chapter 5 explores the interplay of race, gender, and salvation in William Shakespeare’s The Merchant of Venice, John Fletcher’s The Island Princess, and Philip Massinger’s The Renegado. The frequency with which Jewish, Turkish, and Moorish women convert to Christianity in English drama more generally responds to the convergence of theological and medical discourses that highlighted the role of male seed in creating a child’s identity, and reflects as well Reformation theology’s linkage of spiritual and sexual reproduction. Nonetheless, anxieties about what an infidel mother might pass on to her children, even when she is married to a Christian man, prompt Fletcher’s and Massinger’s plays to employ the discourse of martyrdom in order to verify the women’s acquisitions of true Christian faith.Less
Whereas numerous infidel women convert to Christianity on the early modern English stage, relatively few infidel men convert. Chapter 5 explores the interplay of race, gender, and salvation in William Shakespeare’s The Merchant of Venice, John Fletcher’s The Island Princess, and Philip Massinger’s The Renegado. The frequency with which Jewish, Turkish, and Moorish women convert to Christianity in English drama more generally responds to the convergence of theological and medical discourses that highlighted the role of male seed in creating a child’s identity, and reflects as well Reformation theology’s linkage of spiritual and sexual reproduction. Nonetheless, anxieties about what an infidel mother might pass on to her children, even when she is married to a Christian man, prompt Fletcher’s and Massinger’s plays to employ the discourse of martyrdom in order to verify the women’s acquisitions of true Christian faith.
Leo W. Beukeboom and Nicolas Perrin
- Published in print:
- 2014
- Published Online:
- August 2014
- ISBN:
- 9780199657148
- eISBN:
- 9780191748103
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199657148.003.0001
- Subject:
- Biology, Evolutionary Biology / Genetics
Sex and genders occupy a central place in the human mind and have a long history of alternative interpretations throughout human cultures. Although intimately linked to reproduction in animals and ...
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Sex and genders occupy a central place in the human mind and have a long history of alternative interpretations throughout human cultures. Although intimately linked to reproduction in animals and other multicellular eukaryotes, sex is fundamentally not a reproductive process. This chapter first discusses what sex is and why it evolved, arguing that it is best defined by the presence of meiosis, that it might have originated as a DNA-repair mechanism, and is likely maintained by indirect benefits stemming from recombination.We then present the several kinds of mating categories (mating types, sexes, genders, self-incompatibility systems), discussing their similarities and differences, and the reasons why they exist. We introduce the concepts of sex-ratio selection and sexual selection, which are arguably the main evolutionary forces underlying the dynamics of sex-determination systems. Finally, this chapter we argues against the traditional distinction between sex determination and primary sex differentiation, defining sex determination as the whole process that leads, from undifferentiated gonads or meristems, to the development of differentiated reproductive organs. This broad definition widens the scope of our book, to also include, for example, sex differentiation in simultaneous and sequential hermaphrodites.Less
Sex and genders occupy a central place in the human mind and have a long history of alternative interpretations throughout human cultures. Although intimately linked to reproduction in animals and other multicellular eukaryotes, sex is fundamentally not a reproductive process. This chapter first discusses what sex is and why it evolved, arguing that it is best defined by the presence of meiosis, that it might have originated as a DNA-repair mechanism, and is likely maintained by indirect benefits stemming from recombination.We then present the several kinds of mating categories (mating types, sexes, genders, self-incompatibility systems), discussing their similarities and differences, and the reasons why they exist. We introduce the concepts of sex-ratio selection and sexual selection, which are arguably the main evolutionary forces underlying the dynamics of sex-determination systems. Finally, this chapter we argues against the traditional distinction between sex determination and primary sex differentiation, defining sex determination as the whole process that leads, from undifferentiated gonads or meristems, to the development of differentiated reproductive organs. This broad definition widens the scope of our book, to also include, for example, sex differentiation in simultaneous and sequential hermaphrodites.
Claus Nielsen
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199606023
- eISBN:
- 9780191774706
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199606023.003.0003
- Subject:
- Biology, Evolutionary Biology / Genetics, Animal Biology
Comprised of only about 200 species, the Choanoflagellata is a small phylum that occurs in most aquatic habitats. Choanoflagellates are unicellular, solitary, or colony-forming ‘flagellates’ without ...
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Comprised of only about 200 species, the Choanoflagellata is a small phylum that occurs in most aquatic habitats. Choanoflagellates are unicellular, solitary, or colony-forming ‘flagellates’ without chloroplasts, and are either pelagic or sessile. They reproduce by binary fission, and sexual reproduction is implied by the presence of conserved meiotic genes. In addition, choanoflagellates have a complicated life cycle. Their sister-group relationship with metazoans is supported by morphological and molecular evidence.Less
Comprised of only about 200 species, the Choanoflagellata is a small phylum that occurs in most aquatic habitats. Choanoflagellates are unicellular, solitary, or colony-forming ‘flagellates’ without chloroplasts, and are either pelagic or sessile. They reproduce by binary fission, and sexual reproduction is implied by the presence of conserved meiotic genes. In addition, choanoflagellates have a complicated life cycle. Their sister-group relationship with metazoans is supported by morphological and molecular evidence.
Thomas H. Luxon
- Published in print:
- 2013
- Published Online:
- August 2015
- ISBN:
- 9780816680764
- eISBN:
- 9781452948560
- Item type:
- chapter
- Publisher:
- University of Minnesota Press
- DOI:
- 10.5749/minnesota/9780816680764.003.0011
- Subject:
- History, World Early Modern History
This chapter discusses John Milton’s account of prelapsarian existence in Paradise Lost, which implies that the first human sexual reproduction occurred between God and Adam in an act that ...
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This chapter discusses John Milton’s account of prelapsarian existence in Paradise Lost, which implies that the first human sexual reproduction occurred between God and Adam in an act that overwhelmed Adam and produced Eve as a new sexual partner for man. Based on the Lucretian meditation on mixed modes of generation, the first act of sexual reproduction makes a materialist and philosophical contribution to the discussion of Milton’s construction of paradise as a place resistant to but tempted by obsolete and “fallen” forms of categorization.Less
This chapter discusses John Milton’s account of prelapsarian existence in Paradise Lost, which implies that the first human sexual reproduction occurred between God and Adam in an act that overwhelmed Adam and produced Eve as a new sexual partner for man. Based on the Lucretian meditation on mixed modes of generation, the first act of sexual reproduction makes a materialist and philosophical contribution to the discussion of Milton’s construction of paradise as a place resistant to but tempted by obsolete and “fallen” forms of categorization.
Andrew F. G. Bourke
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199231157
- eISBN:
- 9780191774553
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199231157.003.0001
- Subject:
- Biology, Evolutionary Biology / Genetics
A series of major transitions in evolution has generated the biological hierarchy (e.g., genes in cells, cells in organisms, organisms in societies) observed today. Each transition requires that ...
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A series of major transitions in evolution has generated the biological hierarchy (e.g., genes in cells, cells in organisms, organisms in societies) observed today. Each transition requires that previously selfish, free-living individuals join together to form a group resembling an individual in its own right. This book seeks to identify the principles of social evolution that underlie the major transitions, focusing on the evolution of the eukaryotic cell, sexual reproduction, multicellularity, eusociality, and interspecific mutualisms. It suggests that each major transition has three stages – social group formation, social group maintenance, and social group transformation. Using Hamilton's inclusive fitness theory (kin selection theory) as its conceptual foundation, the book investigates two underexplored issues. First, to what extent do common principles operate at each stage of the major transitions and what is the evidence for their operation; and second, what are the principles underlying social group transformation?Less
A series of major transitions in evolution has generated the biological hierarchy (e.g., genes in cells, cells in organisms, organisms in societies) observed today. Each transition requires that previously selfish, free-living individuals join together to form a group resembling an individual in its own right. This book seeks to identify the principles of social evolution that underlie the major transitions, focusing on the evolution of the eukaryotic cell, sexual reproduction, multicellularity, eusociality, and interspecific mutualisms. It suggests that each major transition has three stages – social group formation, social group maintenance, and social group transformation. Using Hamilton's inclusive fitness theory (kin selection theory) as its conceptual foundation, the book investigates two underexplored issues. First, to what extent do common principles operate at each stage of the major transitions and what is the evidence for their operation; and second, what are the principles underlying social group transformation?
Jonathan Morton
- Published in print:
- 2018
- Published Online:
- March 2018
- ISBN:
- 9780198816669
- eISBN:
- 9780191858314
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198816669.003.0003
- Subject:
- Literature, Early and Medieval Literature
The chapter outlines different models of nature in medieval Aristotelian and Platonic philosophy in order to show how the Rose plays them against each other to articulate its own model of the complex ...
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The chapter outlines different models of nature in medieval Aristotelian and Platonic philosophy in order to show how the Rose plays them against each other to articulate its own model of the complex relationship between art and nature. For the Rose there is no getting at nature except by means of art, as suggested by the self-conscious artificiality of the figure of Nature, taken from the allegories of twelfth-century Neoplatonism. Art, a broad category that encompasses all human activity, is insufficient in describing nature’s truths and is potentially sophistic in its lies. However, questions of nature are always questions of art on whose help humans depend to understand and to represent to themselves a nature that can never be fully known. Finally, the model of reproductive nature is used to legitimate the reproduction of texts and the continuation of arts that is literary production.Less
The chapter outlines different models of nature in medieval Aristotelian and Platonic philosophy in order to show how the Rose plays them against each other to articulate its own model of the complex relationship between art and nature. For the Rose there is no getting at nature except by means of art, as suggested by the self-conscious artificiality of the figure of Nature, taken from the allegories of twelfth-century Neoplatonism. Art, a broad category that encompasses all human activity, is insufficient in describing nature’s truths and is potentially sophistic in its lies. However, questions of nature are always questions of art on whose help humans depend to understand and to represent to themselves a nature that can never be fully known. Finally, the model of reproductive nature is used to legitimate the reproduction of texts and the continuation of arts that is literary production.
Simon J. Evnine
- Published in print:
- 2016
- Published Online:
- August 2016
- ISBN:
- 9780198779674
- eISBN:
- 9780191825989
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198779674.003.0005
- Subject:
- Philosophy, Metaphysics/Epistemology
The account of hylomorphic structure developed for artifacts is in this chapter extended to organisms. An account is given of the origin of organisms in sexual reproduction that is modeled on the ...
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The account of hylomorphic structure developed for artifacts is in this chapter extended to organisms. An account is given of the origin of organisms in sexual reproduction that is modeled on the artifactual account but that, of course, lacks the important role of intentional making. It is then argued, drawing on work by Karen Neander and Ruth Millikan, that something similar to what intentional making does in the case of artifacts is accomplished by evolution in the case of organisms. Cases like that of Davidson’s Swampman are not cases of organisms, or hylomorphically complex entities of any kind, at all.Less
The account of hylomorphic structure developed for artifacts is in this chapter extended to organisms. An account is given of the origin of organisms in sexual reproduction that is modeled on the artifactual account but that, of course, lacks the important role of intentional making. It is then argued, drawing on work by Karen Neander and Ruth Millikan, that something similar to what intentional making does in the case of artifacts is accomplished by evolution in the case of organisms. Cases like that of Davidson’s Swampman are not cases of organisms, or hylomorphically complex entities of any kind, at all.
Claus Nielsen
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199606023
- eISBN:
- 9780191774706
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199606023.003.0009
- Subject:
- Biology, Evolutionary Biology / Genetics, Animal Biology
The Homoscleromorpha is a small phylum consisting of roughly sixty extant species of marine ‘sponges’. Previously placed within the Demospongiae, both morphological and molecular studies now indicate ...
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The Homoscleromorpha is a small phylum consisting of roughly sixty extant species of marine ‘sponges’. Previously placed within the Demospongiae, both morphological and molecular studies now indicate that it is a separate phylum. The basal membrane contains collagen IV, which, along with recent molecular studies, supports a sister-group relationship between the homoscleromorphs and the eumetazoans. During sexual reproduction of the homoscleromorphs, spermatogonia develop from choanocytes and whole choanocyte chambers differentiate into spermiocysts. Both homoscleromorphs and eumetazoans possess a large number of cell-signalling and adhesion genes, some of which are absent in Amphimedon.Less
The Homoscleromorpha is a small phylum consisting of roughly sixty extant species of marine ‘sponges’. Previously placed within the Demospongiae, both morphological and molecular studies now indicate that it is a separate phylum. The basal membrane contains collagen IV, which, along with recent molecular studies, supports a sister-group relationship between the homoscleromorphs and the eumetazoans. During sexual reproduction of the homoscleromorphs, spermatogonia develop from choanocytes and whole choanocyte chambers differentiate into spermiocysts. Both homoscleromorphs and eumetazoans possess a large number of cell-signalling and adhesion genes, some of which are absent in Amphimedon.
R. M. M. Crawford
- Published in print:
- 2013
- Published Online:
- May 2015
- ISBN:
- 9780199559404
- eISBN:
- 9780191810053
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:osobl/9780199559404.003.0008
- Subject:
- Biology, Ecology
This chapter examines the resilience of arctic biota to climatic fluctuations and disturbance. The ability to repair decimated populations by sexual reproduction or, as in the case with plants, also ...
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This chapter examines the resilience of arctic biota to climatic fluctuations and disturbance. The ability to repair decimated populations by sexual reproduction or, as in the case with plants, also asexually is all the more astonishing given the climatic and resource limitations of high-latitude habitats. This ability of the arctic biota to recover from near extinction may be attributed to the reduced inter-specific competition that can be enjoyed in the sparseness of the arctic landscapes. The chapter discusses reproduction at high latitudes; human demography in the Arctic; longevity at high latitudes; predator-prey interactions; phenology and reproduction; and plant reproduction.Less
This chapter examines the resilience of arctic biota to climatic fluctuations and disturbance. The ability to repair decimated populations by sexual reproduction or, as in the case with plants, also asexually is all the more astonishing given the climatic and resource limitations of high-latitude habitats. This ability of the arctic biota to recover from near extinction may be attributed to the reduced inter-specific competition that can be enjoyed in the sparseness of the arctic landscapes. The chapter discusses reproduction at high latitudes; human demography in the Arctic; longevity at high latitudes; predator-prey interactions; phenology and reproduction; and plant reproduction.
Carrie Friese
- Published in print:
- 2013
- Published Online:
- March 2016
- ISBN:
- 9780814729083
- eISBN:
- 9780814729090
- Item type:
- chapter
- Publisher:
- NYU Press
- DOI:
- 10.18574/nyu/9780814729083.003.0005
- Subject:
- Sociology, Health, Illness, and Medicine
This chapter explores how cloning reproduces and sustains the centrality of sex in the biopolitics of the zoo. Focusing on the cloned banteng, it considers the so-called “genetic values” that are so ...
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This chapter explores how cloning reproduces and sustains the centrality of sex in the biopolitics of the zoo. Focusing on the cloned banteng, it considers the so-called “genetic values” that are so central to zoological parks today. In this context, the zoo is envisioned not as a place populated by hundreds of clones, carbon copies of endangered animals living in the wild, but as a place that uses available technologies in order to manage sexual reproduction, and thus sustain a deftly balanced genetic composition within a limited amount of space. The chapter analyzes the context of genetic value vis-à-vis the ways in which selective breeding has historically been constituted to create what Harriet Ritvo has called “genetic capital” in agriculture. It also discusses the biopolitics of genetic values in the case of domestic animals and concludes by examining genetic values in relation to nature and culture, as well as the kinds of wild life and endangered species that are enabled by the genetic values of zoos.Less
This chapter explores how cloning reproduces and sustains the centrality of sex in the biopolitics of the zoo. Focusing on the cloned banteng, it considers the so-called “genetic values” that are so central to zoological parks today. In this context, the zoo is envisioned not as a place populated by hundreds of clones, carbon copies of endangered animals living in the wild, but as a place that uses available technologies in order to manage sexual reproduction, and thus sustain a deftly balanced genetic composition within a limited amount of space. The chapter analyzes the context of genetic value vis-à-vis the ways in which selective breeding has historically been constituted to create what Harriet Ritvo has called “genetic capital” in agriculture. It also discusses the biopolitics of genetic values in the case of domestic animals and concludes by examining genetic values in relation to nature and culture, as well as the kinds of wild life and endangered species that are enabled by the genetic values of zoos.
Lincoln Taiz and Lee Taiz
- Published in print:
- 2017
- Published Online:
- July 2018
- ISBN:
- 9780190490263
- eISBN:
- 9780190868673
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780190490263.003.0001
- Subject:
- Biology, Ecology, Plant Sciences and Forestry
Chapter one describes “The Quandary Over Plant Sex” in its historical context. The sexual role of pollen wasn’t discovered until the late 17th century, suggesting a deep cultural bias. Beliefs ...
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Chapter one describes “The Quandary Over Plant Sex” in its historical context. The sexual role of pollen wasn’t discovered until the late 17th century, suggesting a deep cultural bias. Beliefs concerning sex in humans, from Galen and Aristotle onward, were influenced by gender ideology. The lower social status of women suggested a one-sex model, whereby female character and physiology were construed as deficient versions of the male. Plants, because of their association with women, came to be regarded as female. Flowers are often emblematic of women in literature, but flowers seem to produce fruits without carnality, by parthenogenesis. In paintings of the Annunciation, the lily appears almost as regularly as the angel Gabriel as a symbol of Mary’s purity. The association of flowers with female purity hindered the discovery of sex in plants. Although most people are aware of pollen, widespread confusion about its role in sexual reproduction still lingers.Less
Chapter one describes “The Quandary Over Plant Sex” in its historical context. The sexual role of pollen wasn’t discovered until the late 17th century, suggesting a deep cultural bias. Beliefs concerning sex in humans, from Galen and Aristotle onward, were influenced by gender ideology. The lower social status of women suggested a one-sex model, whereby female character and physiology were construed as deficient versions of the male. Plants, because of their association with women, came to be regarded as female. Flowers are often emblematic of women in literature, but flowers seem to produce fruits without carnality, by parthenogenesis. In paintings of the Annunciation, the lily appears almost as regularly as the angel Gabriel as a symbol of Mary’s purity. The association of flowers with female purity hindered the discovery of sex in plants. Although most people are aware of pollen, widespread confusion about its role in sexual reproduction still lingers.
Claus Nielsen
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199606023
- eISBN:
- 9780191774706
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199606023.003.0002
- Subject:
- Biology, Evolutionary Biology / Genetics, Animal Biology
In Systema Naturæ (1735, 1758), Carolus Linnaeus proposed a definition of the Kingdom Animalia: natural objects that grow, live, and sense. In contrast, plants grow and live but do not sense, while ...
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In Systema Naturæ (1735, 1758), Carolus Linnaeus proposed a definition of the Kingdom Animalia: natural objects that grow, live, and sense. In contrast, plants grow and live but do not sense, while minerals grow but do not live or sense. In this definition of the animal kingdom, species are arranged in classes, families, and genera. This division of organisms into animals and plants was almost unchallenged for more than 100 years. In 1866, Ernst Haeckel came up with the first classification of living beings based on Charles Darwin’s ideas on evolution. He separated the Kingdom Animalia from the new Kingdom Protista based on the possession of tissues and organs. Today, the animal kingdom is restricted to multicellular animals, that is, the Metazoa. This chapter provides an overview of metazoans, including their apomorphies, sexual reproduction and life cycle, and genes involved in organising the metazoan body. It also describes some of the metazoan morphological characters, including cilia and flagella, choanocytes, cell junctions and epithelia.Less
In Systema Naturæ (1735, 1758), Carolus Linnaeus proposed a definition of the Kingdom Animalia: natural objects that grow, live, and sense. In contrast, plants grow and live but do not sense, while minerals grow but do not live or sense. In this definition of the animal kingdom, species are arranged in classes, families, and genera. This division of organisms into animals and plants was almost unchallenged for more than 100 years. In 1866, Ernst Haeckel came up with the first classification of living beings based on Charles Darwin’s ideas on evolution. He separated the Kingdom Animalia from the new Kingdom Protista based on the possession of tissues and organs. Today, the animal kingdom is restricted to multicellular animals, that is, the Metazoa. This chapter provides an overview of metazoans, including their apomorphies, sexual reproduction and life cycle, and genes involved in organising the metazoan body. It also describes some of the metazoan morphological characters, including cilia and flagella, choanocytes, cell junctions and epithelia.
Mariska Leunissen
- Published in print:
- 2017
- Published Online:
- July 2017
- ISBN:
- 9780190602215
- eISBN:
- 9780190602239
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780190602215.003.0004
- Subject:
- Philosophy, Ancient Philosophy, General
Chapter 4 takes up Aristotle’s theory of eugenics, which encourages lawgivers not to leave the birth of offspring in their cities up to chance, but to put policies in place that promote the birth of ...
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Chapter 4 takes up Aristotle’s theory of eugenics, which encourages lawgivers not to leave the birth of offspring in their cities up to chance, but to put policies in place that promote the birth of male offspring with the type of natural character traits that are most conducive to moral development. I argue that the specific policies Aristotle recommends to these lawgivers take their facts from his biological theories about reproduction and sexual differentiation. I also discuss Aristotle’s conceptions of “good birth” and “natural talent” that are mentioned outside his biological treatises, but that he claims can be acquired only through birth and bring natural advantages to their possessors in terms of acquiring virtue more easily.Less
Chapter 4 takes up Aristotle’s theory of eugenics, which encourages lawgivers not to leave the birth of offspring in their cities up to chance, but to put policies in place that promote the birth of male offspring with the type of natural character traits that are most conducive to moral development. I argue that the specific policies Aristotle recommends to these lawgivers take their facts from his biological theories about reproduction and sexual differentiation. I also discuss Aristotle’s conceptions of “good birth” and “natural talent” that are mentioned outside his biological treatises, but that he claims can be acquired only through birth and bring natural advantages to their possessors in terms of acquiring virtue more easily.
Greg Anderson
- Published in print:
- 2018
- Published Online:
- October 2018
- ISBN:
- 9780190886646
- eISBN:
- 9780190886677
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780190886646.003.0016
- Subject:
- Classical Studies, World History: BCE to 500CE
To conclude the book’ s alternative account of the Athenian politeia, the chapter offers a recursive analysis of the resource flows which made this way of life possible. The result is very different ...
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To conclude the book’ s alternative account of the Athenian politeia, the chapter offers a recursive analysis of the resource flows which made this way of life possible. The result is very different from a conventional modern secular economic analysis. Instead, it treats resource transactions as the lifeblood of a cosmic ecology that united gods, land, and people in a condition of symbiotic interdependency. The most important of all these transactions were those between gods and humans, whereby the latter received secure conditions of existence in exchange for temples, sacrifices, votive treasures, and other often costly ritual offerings. The most important of the resource transactions between humans were marriages, whereby the managerial and reproductive capacities of females were transferred from one household to another, thereby perpetuating the life of the social body. Contrary to the “egalitarian” ethos which moderns believe animated “democratic Athens,” demokratia would also have been unsustainable without the innumerable contributions of resources, material and otherwise, that were made by a relatively small number of super-wealthy Athenian households. And in a polis where members typically worked only for themselves, the existence of these ecologically essential super-wealthy households would have been unsustainable without the routine exploitation of slaves.Less
To conclude the book’ s alternative account of the Athenian politeia, the chapter offers a recursive analysis of the resource flows which made this way of life possible. The result is very different from a conventional modern secular economic analysis. Instead, it treats resource transactions as the lifeblood of a cosmic ecology that united gods, land, and people in a condition of symbiotic interdependency. The most important of all these transactions were those between gods and humans, whereby the latter received secure conditions of existence in exchange for temples, sacrifices, votive treasures, and other often costly ritual offerings. The most important of the resource transactions between humans were marriages, whereby the managerial and reproductive capacities of females were transferred from one household to another, thereby perpetuating the life of the social body. Contrary to the “egalitarian” ethos which moderns believe animated “democratic Athens,” demokratia would also have been unsustainable without the innumerable contributions of resources, material and otherwise, that were made by a relatively small number of super-wealthy Athenian households. And in a polis where members typically worked only for themselves, the existence of these ecologically essential super-wealthy households would have been unsustainable without the routine exploitation of slaves.
