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At least 1,135 records · Page 63Linked to original sources
PubMed1995

Founder-effect speciation theory: failure of experimental corroboration.

The theory of founder-effect speciation proposes that colonization by very few individuals of an empty habitat favors rapid genetic changes and the evolution of a new species. We report here the results obtained in a 10-year-long and large-scale experiment with Drosophila pseudoobscura designed to test the theory. In our experimental protocol, populations are established with variable numbers of very few individuals and allowed to expand greatly for several generations until conditions of severe competition for resources are reached and the population crashes. A few random survivors are then taken to start a new population expansion and thus initiate a new cycle of founding events, population flushes, and crashes. Our results provide no support for the theories proposing that new species are very likely to appear as by-products of founder events.

Animals↗
PubMed1999

The mating-type and pathogenicity locus of the fungus Ustilago hordei spans a 500-kb region.

The fungal pathogen Ustilago hordei causes the covered smut disease of barley and oats. Mating and pathogenicity in this fungus are controlled by the MAT locus, which contains two distinct gene complexes, a and b. In this study, we tagged the a and b regions with the recognition sequence for the restriction enzyme I-SceI and determined that the distance between the complexes is 500 kb in a MAT-1 strain and 430 kb in a MAT-2 strain. Characterization of the organization of the known genes within the a and b gene complexes provided evidence for nonhomology and sequence inversion between MAT-1 and MAT-2. Antibiotic-resistance markers also were used to tag the a gene complex in MAT-1 strains (phleomycin) and the b gene complex in MAT-2 strains (hygromycin). Crosses were performed with these strains and progeny resistant to both antibiotics were recovered at a very low frequency, suggesting that recombination is suppressed within the MAT region. Overall, the chromosome homologues carrying the MAT locus of U. hordei share features with primitive sex chromosomes, with the added twist that the MAT locus also controls pathogenicity.

Avena↗
PubMed1998

A bad disease, a fatal cure: why sterilization is permissible and the autonomy of medicine is not.

The debate in this issue regarding the Roman Catholic condemnation of the morality of sterilization is puzzling for Protestants. As I will argue the puzzlement arises on two grounds. First, why would anyone object to direct sterilization for the cure or prevention of disease? Second, if one wanted to challenge such an objection on moral grounds why would one turn to medicine to do so? For Christian ethics there is nothing wrong in principle with direct sterilization when there are good reasons for precluding the possibility of an additional pregnancy; and it is a serious theological mistake to treat medicine as an independent moral authority.

Catholicism↗
PubMed1998

Sexual ethics and communal judgments: on the pluralism of virtues, values, and practices.

Different judgments by Christian communities on issues in sexual ethics involve different weightings of various sources of moral authority, different understandings of the normativity of the natural, and different assessments of the scope of freedom to be exercised in relation to the goods of marriage. These fundamental differences of interpretation can be exemplified by the ongoing Roman Catholic discussion of the legitimacy of voluntary sterilization in certain "hard cases." The contributors to this issue of Christian Bioethics, in their spirited exchange on that issue, exemplify the need for careful attention to the ways that differences of theological emphasis and moral method lead to different judgements in particular cases, both within and between particular Christian communities.

Catholicism↗
PubMed1998

There is no moral authority in medicine: response to Cowdin and Tuohey.

Central to the Cowdin-Tuohey paper is the concept of a moral authority proper to medical practitioners. Much as I agree with the authors in refusing to degrade doctors to the status of mere technicians, I argue that one does not succeed in retrieving the moral dimension of medical practice by investing doctors with moral authority. I show that none of the cases brought forth by Cowdin-Tuohey really amounts to a case of moral authority. Then I try to explain why no such cases can be found. Developing an insight that is common to all the major moral thinkers in the philosophia perennis, I show that doctors are professionally competent with respect only to a part of the human good; morally wise persons are competent with respect to that which makes man good as man. I try to show why it follows that a) professional expertise has no natural tendency to pass over into moral understanding, and that b) doctor and non-doctor alike start from the same point in developing their understanding of medical morality. It follows that the authors fail in their attempt to de-center the moral magisterium of the Church by setting up centers of moral authority outside of the Church.

Abortion, Induced↗
PubMed1998

Bioethics and humanities: what makes us one field?

Bioethics and humanities (inclusive of medical ethics, health care ethics, environmental ethics, research ethics, philosophy and medicine, literature and medicine, and so on) seems like one field; yet colleagues come from different academic disciplines with distinct languages, methods, traditions, core curriculum and competency examinations. The author marks six related "framework" features that unite and make it one distinct field. It is a commitment to (1) work systematically on some of the momentous and well-defined sets of problems about the human condition that drive our field (such as death and dying, disability, confidentiality, professionalism, informed consent, abortion, euthanasia, assisted suicide, personhood, health-care resource allocation and environmental ethics, as well as the impact of new technologies, including genetic and reproductive); (2) use interdisciplinary approaches to unravel them; (3) employ cases and practical reasoning to understand problems and solve answers; (4) apply teaching methods and goals associated with John Dewey to make students better problem-solvers; (5) find morally justifiable solutions to the problems driving our field; and (6) seek interdisciplinary and collaborative scholarship, service or teaching.

Bioethical Issues↗
PubMed2001

Yin-yang genetics, or the HSD deCODE controversy.

Iceland has attracted world-wide attention because of a controversy surrounding the Icelandic Health Sector Database Act of 1998 and the genomics company deCODE Genetics. The controversy concerns limits to state power, bioethics and regulation of research, and civil liberties. Understanding it necessitates paying attention to the yin-yang-like character of deCODE; it is international or Icelandic, what is the relation between the HSD and deCODE, will the HSD engulf the Icelandic nation as a whole?

Databases, Genetic↗
PubMed2003

Actor-network theory: a tool to support ethical analysis of commercial genetic testing.

Social, ethical and policy analysis of the issues arising from gene patenting and commercial genetic testing is enhanced by the application of science and technology studies, and Actor-Network Theory (ANT) in particular. We suggest the potential for transferring ANT's flexible nature to an applied heuristic methodology for gathering empirical information and for analysing the complex networks involved in the development of genetic technologies. Three concepts are explored in this paper--actor-networks, translation, and drift--and applied to the case of Myriad Genetics and their commercial BRACAnalysis genetic susceptibility test for hereditary breast cancer. Treating this test as an active participant in socio-technical networks clarifies the extent to which it interacts with, shapes and is shaped by people, other technologies, and institutions. Such an understanding enables more sophisticated and nuanced technology assessment, academic analysis, as well as public debate about the social, ethical and policy implications of the commercialization of new genetic technologies.

Breast Neoplasms↗
PubMedDate not supplied

Toward an evolutionary forensic psychology.

Most theories of crime have not explored intensively biological and especially evolutionary explanations for criminal behavior. Ellis presents a valuable new perspective that proposes that attention to physiological mechanisms shaped by evolutionary forces can provide insights into the causes of crime and sex differences in the patterns of crime. We discuss other theories and research relevant to Ellis' theory. We also propose that an evolutionary psychological perspective of crime will help to invigorate research and lead to a better understanding of criminality. An integrated evolutionary forensic psychology will help to explain sources of conflict between individuals, situations in which conflict leads to victimization, and victim defenses and coping mechanisms.

Age Factors↗
PubMed1996

Genetic conflicts.

Self-promoting elements (also called ultraselfish genes, selfish genes, or selfish genetic elements) are vertically transmitted genetic entities that manipulate their "host" so as to promote their own spread, usually at a cost to other genes within the genome. Examples of such elements include meiotic drive genes and cytoplasmic sex ratio distorters. The spread of a self-promoting element creates the context for the spread of a suppressor acting within the same genome. We may thus say that a genetic conflict exists between different components of the same genome. Here we investigate the properties of such conflicts. First we consider the potential diversity of genomic conflicts and show that every genetic system has potential conflicts. This is followed by analysis of the logic of conflicts. Just as Evolutionarily Stable Strategy (ESS) terminology provides a short cut for discussion of much in behavioral ecology, so the language of modifier analysis provides a useful terminology on which to base discussions of conflicts. After defining genetic conflict, we provide a general analysis of the conflicting parties, and note a distinction between competing and conflicting genes. We then provide a taxonomy of possible short- and long-term outcomes of conflicts, noting that potential conflict in an unconstrained system can never be removed, and that the course of evolution owing to conflict is often unpredictable. The latter is most particularly true for strong conflicts in which suppressors may take surprising forms. The possibility of extended conflicts in the form of "arms races" between element and suppressor is illustrated. The peculiar redundancy of these systems is one possible trace of conflict, and others are discussed. That homologous conflicts may find highly different expression is discussed by referring to the mechanistic differences that are thought to underlie the action of the two best-described meiotic drive genes, and by the multiplicity of forms of cytoplasmic sex ratio distorters. The theoretical analysis establishes a logical basis for thinking about conflicts, but fails to establish the importance of conflict in evolution. We illustrate this contentious issue through consideration of some phenomena for whose evolution conflict has been proposed as an important force: the evolution of sex, sex determination, species, recombination, and uniparental inheritance of cytoplasmic genes. In general, it is proposed that conflict may be a central force in the evolution of genetic systems. We conclude that an analysis of conflict and its general importance in evolution is greatly aided by application of the concept of genetic power. We consider the possible components of genetic power and ask whether and how power evolves.

Animals↗
PubMed1990

Controversies in research ethics affecting the future of human gene therapy.

A critical analysis is undertaken of the ethical debate on two general classes of research activities that bear on the future of human gene therapy: (i) the human fetus and (ii) the preimplantation human embryo after in vitro fertilization (IVF). The conclusion is that the hope of human gene therapy and of other clinical applications of the human genome initiative is in danger because of the obstacles to research in reproductive biology and human genetics in the federal sector.

Aborted Fetus↗