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At least 559 records · Page 31Linked to original sources
PubMed2006

Assessing the effects of human mixing patterns on human immunodeficiency virus-1 interhost phylogenetics through social network simulation.

Geneticists seeking to understand HIV-1 evolution among human hosts generally assume that hosts represent a panmictic population. Social science research demonstrates that the network patterns over which HIV-1 spreads are highly nonrandom, but the effect of these patterns on the genetic diversity of HIV-1 and other sexually transmitted pathogens has yet to be thoroughly examined. In addition, interhost phylogenetic models rarely account explicitly for genetic diversity arising from intrahost dynamics. This study outlines a graph-theoretic framework (exponential random graph modeling, ERGM) for the estimation, inference, and simulation of dynamic partnership networks. This approach is used to simulate HIV-1 transmission and evolution under eight mixing patterns resembling those observed in empirical human populations, while simultaneously incorporating intrahost viral diversity. Models of parametric growth fit panmictic populations well, yielding estimates of total viral effective population on the order of the product of infected host size and intrahost effective viral population size. Populations exhibiting patterns of nonrandom mixing differ more widely in estimates of effective population size they yield, however, and reconstructions of population dynamics can exhibit severe errors if panmixis is assumed. I discuss implications for HIV-1 phylogenetics and the potential for ERGM to provide a general framework for addressing these issues.

Evolution, Molecular↗
PubMed2000

Clutch size evolution under sexual conflict enhances the stability of mating systems.

Models of optimal clutch size often implicitly assume a situation with uniparental care. However, the evolutionary conflict between males and females over the division of parental care will have a major influence on the evolution of clutch size. Since clutch size is a female trait, a male has little possibility of directly influencing it. However, the optimal clutch size from a female's perspective will depend on the amount of paternal care her mate is expected to provide. The sexual conflict over parental care will in its turn be affected by clutch size, since a larger clutch makes male care more valuable. Hence, there will be joint evolution of mating system and clutch size. In this paper, we demonstrate that this joint evolution will tend to stabilize the mating system. In a situation with conventional sex roles, this joint evolution might result in either increased clutch size and biparental care or reduced clutch size and uniparental female care. Under some circumstances the initial conditions might determine which will be the outcome. These results demonstrate that it may be difficult to deduce whether biparental care evolved because of few opportunities for breeding males increasing their fitness by attracting additional mates or because of the importance of male care for offspring fitness by studying prevailing mating systems using, for example, male removals or manipulation of males' opportunities for finding additional mates. In general terms, we demonstrate that models of life-history evolution have to consider the social context in which they evolve.

Animals↗
PubMed2006

Evolution of cooperative strategies from first principles.

One of the greatest challenges in the modern biological and social sciences is to understand the evolution of cooperative behaviour. General outlines of the answer to this puzzle are currently emerging as a result of developments in the theories of kin selection, reciprocity, multilevel selection and cultural group selection. The main conceptual tool used in probing the logical coherence of proposed explanations has been game theory, including both analytical models and agent-based simulations. The game-theoretic approach yields clear-cut results but assumes, as a rule, a simple structure of payoffs and a small set of possible strategies. Here we propose a more stringent test of the theory by developing a computer model with a considerably extended spectrum of possible strategies. In our model, agents are endowed with a limited set of receptors, a set of elementary actions and a neural net in between. Behavioural strategies are not predetermined; instead, the process of evolution constructs and reconstructs them from elementary actions. Two new strategies of cooperative attack and defence emerge in simulations, as well as the well-known dove, hawk and bourgeois strategies. Our results indicate that cooperative strategies can evolve even under such minimalist assumptions, provided that agents are capable of perceiving heritable external markers of other agents.

Animals↗
PubMed2000

'Culture' in quail: social influences on mate choices of female Coturnix japonica.

We have shown previously that after a focal female Japanese quail, Coturnix japonica, sees a conspecific male mating, the focal female's tendency to affiliate and to mate with that male is significantly increased. Here we describe two experiments demonstrating that a focal female quail that has seen a conspecific male mating subsequently shows an enhanced tendency to affiliate not only with that particular male, but also with other males that share his characteristics. The results have important implications for our understanding of the role of social learning in the evolution of male characteristics. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2006

Lower disease infections in honeybee (Apis mellifera) colonies headed by polyandrous vs monandrous queens.

We studied the relationship between genetic diversity and disease susceptibility in honeybee colonies living under natural conditions. To do so, we created colonies in which each queen was artificially inseminated with sperm from either one or ten drones. Of the 20 colonies studied, 80% showed at least one brood disease. We found strong differences between the two types of colonies in the infection intensity of chalkbrood and in the total intensity of all brood diseases (chalkbrood, sacbrood, American foulbrood, and European foulbrood) with both variables lower for the colonies with higher genetic diversity. Our findings demonstrate that disease can be an important factor in the ecology of honeybee colonies and they provide strong support for the disease hypothesis for the evolution of polyandry by social insect queens.

Animals↗
PubMed1984

Pharmacognosy: the oldest modern science.

The use of drugs goes back to time immemorial, ever since primitive man resorted to the world around him to derive remedies which could alleviate pain and cure illnesses. The knowledge of drugs has developed together with the evolution of scientific and social progress. After a rapid historical review on the use of medicinal drugs in the diverse civilizations and on the origin and introduction of the term Pharmacognosy, the acquisitions of modern experimental Pharmacognosy in different countries of the world, and its contribution to therapy are briefly discussed.

China↗
PubMed2005

The vertebrate social behavior network: evolutionary themes and variations.

Based on a wide variety of data, it is now clear that birds and teleost (bony) fish possess a core "social behavior network" within the basal forebrain and midbrain that is homologous to the social behavior network of mammals. The nodes of this network are reciprocally connected, contain receptors for sex steroid hormones, and are involved in multiple forms of social behavior. Other hodological features and neuropeptide distributions are likewise very similar across taxa. This evolutionary conservation represents a boon for experiments on phenotypic behavioral variation, as the extraordinary social diversity of teleost fish and songbirds can now be used to generate broadly relevant insights into issues of brain function that are not particularly tractable in other vertebrate groups. Two such lines of research are presented here, each of which addresses functional variation within the network as it relates to divergent patterns of social behavior. In the first set of experiments, we have used a sexually polymorphic fish to demonstrate that natural selection can operate independently on hypothalamic neuroendocrine functions that are relevant for (1) gonadal regulation and (2) sex-typical behavioral modulation. In the second set of experiments, we have exploited the diversity of avian social organizations and ecologies to isolate species-typical group size as a quasi-independent variable. These experiments have shown that specific areas and peptidergic components of the social behavior network possess functional properties that evolve in parallel with divergence and convergence in sociality.

Animals↗
PubMed2002

Physicians' interpretation of "class effects": a need for thoughtful re-evaluation.

The concept of pharmacologic "class effects" exists across a broad range of medical products and is particularly pervasive with regard to cardiovascular agents. Evolution of the concept over the past two decades has shown the influence of physicians' practice patterns, pharmaceutical companies, health maintenance organizations and the Food and Drug Administration (FDA). Understanding the evolution of health care, social and economic policies, acknowledging the correction of medical misconceptions and inaccurate understanding and appreciating the emergence of new medical knowledge over the past decade should modify the clinician's viewpoint of "class effects." These revelations should signal caution in extrapolating the outcome efficacy or safety of one agent to another within a pharmacologic class. The authors urge clinicians, pharmaceutical companies, health maintenance organizations and the FDA to re-examine their concept of "class effects." An appeal is made for physicians to prescribe those pharmaceutical agents with definitive evidence of mortality and morbidity efficacy and safety established by appropriately scaled randomized clinical trials.

Adrenergic beta-Antagonists↗
PubMed2003

Army ants: an evolutionary bestseller?

Army ants are characterized by a complex combination of behavioral and morphological traits. Molecular data now indicate that army ant behavior has a unique evolutionary origin and has been conserved for over more than 100 million years.

Adaptation, Biological↗
PubMed1993

Contextual sources of information and responses to animal communication signals.

The response of signal recipients depends on information found in the signal itself and on other information sources known collectively as context. Context is the set of events, conditions, and changeable recipient characteristics that modify the effect of a signal on recipients' behavior. Sources of contextual information include (a) the characteristics of the recipient and (b) sources external to the recipient (the signaler and the setting). Contextual information is most commonly used when the signal itself does not provide enough information for the recipient to behave adaptively. The signal's referent may be ambiguous or deceptive, or recipients may need additional information to fine-tune their responses. When animal signals were thought to be information poor, contextual information was seen as being critically informative. Animal signals are now known to be much more informative, but even information-rich systems, such as human language, depend heavily on contextual sources of information.

Animal Communication↗
PubMed2002

The evolution of mutualistic interspecific communication: assessment and management across species.

This article investigates the evolution of interspecific communication within a mutualistic setting, using the assessment-management approach to communication as a theoretical framework. The author introduces sequential stages in the evolution of mutualistic interspecific communication from unilateral assessment, to bilateral assessment, to asymmetric communication, and finally to highly complex, coevolved bilateral assessment and management and presents animal examples of each evolutionary stage. From these examples, the author forms predictions regarding when and how interspecific communication is most likely to develop, along with suggestions for further research.

Animal Communication↗
PubMedDate not supplied

Evolution of information on women and heart disease 1957-2000: a review of archival records and secular literature.

This project explores the evolution of public information on cardiac disease in women, focusing on warning signs and symptoms. Historical documents available from the American Heart Association of Wisconsin and selected professional and secular literature were reviewed. Analysis revealed little information specific to women's symptoms until the 1980s. During the 1960s, articles and programs focused on how women could take care of their husbands' hearts. The 1980s brought a dramatic surge in literature on women's health, specifically on women's risk for heart disease. The evolution of information about women has mirrored the evolution of women's social roles. Despite the growing body of literature, more information and educational programs are needed to increase public awareness of cardiac warning signs and symptoms in women.

Bibliometrics↗
PubMedDate not supplied

There is hope.

Explore the source record for details and available documents.

Biological Evolution↗
PubMedDate not supplied

International relations and epidemics: a short expedition to places inhabited by states and mad cows.

The complex process of co-evolution between humans, their social structures and biological disease agents have from time to time established relationships between the three. Recently, one such set of paths has opened up faster and closer global connections. As new and more inclusive approaches emerge from the shadow of strict intra-disciplinary containment, it is tempting to formulate the relationship between epidemics and international relations in new terms deriving from new metaphors. The argument that components central to international relations (state, sovereignty, power) do not associate with disease can be viewed sceptically. Throughout history, epidemics have had a direct impact on political interaction by vindicating, weakening, testing, and moulding international relations. This paper examines the past relationships between epidemics and international relations, and illustrates these interactions with the example of Bovine Spongiform Encephalopathy (mad cow disease) and its link with human Creutzfeldt-Jakob disease.

Animals↗
PubMed1990

The evolution of clinical policies.

Physicians use clinical policies as guidelines in the day-to-day management of patients. Some policies, by reducing otherwise complicated dilemmas to simple rules, encourage improved patient outcomes, but some are adopted without any evidence of benefit; some may be extended beyond their proper limitations and others are used despite accumulating data that they are at best useless and at worst dangerous. Four stages, development, diffusion, domination, and disillusionment, may be recognized in the evolution of clinical policies. Social rather than scientific forces play a central role, and at each step characteristic errors in both reasoning and research may occur. Attempts to improve patient outcomes by encouraging more appropriate research methodology and increasing the ability of physicians to critically appraise published studies may not be successful unless account is also taken of the social forces that influence the use and abuse of clinical policies.

Attitude of Health Personnel↗
PubMed2002

Do great tits assess rivals by combining direct experience with information gathered by eavesdropping?

Animals frequently use signals that travel further than the spacing between individuals. For every intended recipient of a given signal there are likely to be many other individuals that receive information. Eavesdropping on signalling interactions between other individuals provides a relatively cost-free method of assessing future opponents or mates. Male great tits (Parus major) extract relative information from such interactions between individuals unknown to them. Here, we show that male great tits can take information gathering a stage further and obtain more information about a previously unencountered intruder, by the hitherto unknown capability of combining information gathered by eavesdropping with that derived from their own direct interaction with an individual. Prior experience with an intruder (A) was achieved by subjecting a focal male to different levels of intrusion simulated using interactive playback. This intruder (A) then took part in a simulated interaction with an unknown male (B) outside the territorial boundary of the focal males. In response to subsequent intrusion by the second male (B), focal males showed low song output in response to males that had lost to a male that the subject was able to beat. Males of known high quality, or those about which information was ambiguous, elicited a high level of song output by focal males. We discuss the implications of this finding for the evolution of communication and social behaviour.

Aggression↗