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Understanding the history of systematics bears on contemporary issues such as the distinction between classifications and systems, the belief that ‘natural’ classifications reflect the progressive refinement of our ideas of relationships, and the dubious reputation acquired by systematics. Here I emphasize the extent to which ‘mind’ shapes classifications. I show that groups in biological classifications often have six or fewer members, in line with the number of things that humans can conveniently memorize together. Concerns about memorization are evident in the work of systematists like Tournefort, Linnaeus, and Antoine-Laurent de Jussieu, and the whole hierarchy of George Bentham's and J. D. Hooker's great Genera plantarum is structured by such concerns. An analytical element in Jussieu's work was emphasized by Cuvier and others, and the hierarchy of their classifications reflects more directly aspects of nature as they understood it, although concerns about memorisation remain evident. Linking an understanding of what classifications can represent to the ideas the makers of classifications had about nature makes it clear that classifications are rarely rigid class hierarchies, but are often more like systems. Historically, the synthetic approach, discussed here, tends to lead to systems, the analytical approach, to ‘classifications’. We must remember that systematists’ work is evaluated by other scientists, and by society at large. The confusion evident in systematics simply confirmed the negative perceptions that many people in the nineteenth century had of naturalists, botanists and zoologists, perceptions that persist today. Zoologica Scripta itself, and the Journal of Natural History, which under this title is about the same age, reflect part of this history. I conclude by emphasizing (1) if systems or classifications in the nineteenth century reflect ‘nature’, it is a nature very different from that we understand today, and (2) the extent and the persistence of the opposition between the synthetic and anaytical approaches.  相似文献   

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Modifications can be made to F-actin that do not interfere with the binding of myosin but inhibit force generation, suggesting that actin's internal dynamics are important for muscle contraction. Observations from electron microscopy and x-ray diffraction have shown that subunits in F-actin have a relatively fixed axial rise but a variable twist. One possible explanation for this is that the actin subunits randomly exist in different discrete states of "twist, " with a significant energy barrier separating these states. This would result in very slow torsional transitions. Paracrystals impose increased order on F-actin filaments by reducing the variability in twist. By looking at filaments that have recently been dissociated from paracrystals, we find that F-actin retains a "memory" of its previous environment that persists for many seconds. This would be consistent with slow torsional transitions between discrete states of twist.  相似文献   

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We tested the proposition that there are more species in the tropics because basal clades adapted to warm paleoclimates have been lost in regions now experiencing cool climates. Molecular phylogenies were used to classify species as "basal" and "derived" based on their family, and their richness patterns were contrasted. Path models also evaluated environmental predictors of richness patterns. As predicted, basal clades are more diverse in the lowland tropics, whereas derived clades are more diverse in the extratropics and high-altitude tropics. Seventy-four percent of the variation in bird richness was explained by environmental variables, but models differed for basal and derived groups. The overall gradient is described by the spatial pattern of basal clades, although there are differences in the Old and New Worlds. We conclude that in ecological time, the global richness gradient reflects birds' responses to climatic gradients, partially operating via plants. Over evolutionary time, the gradient primarily reflects the extirpation of species in older clades from parts of the world that have become cooler in the present. A strong secondary effect arises from dispersal of clades from centers of origin and subsequent radiations. Overall, the diversity gradient is well explained by niche conservatism and the "time-for-speciation" hypothesis.  相似文献   

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Recently, the study of niche dynamics using spatial environmental data and species occurrences has become an active field of research. Several studies report niche shifts between native and invasive populations, but it is debated whether these shifts are biologically meaningful or result from methodological artefacts. Using data on the occurrence of non-native birds in Europe, we assess the prevalence of niche shifts along a selected number of climatic variables and find that although niche differences are frequent, biological explanations are often not necessary. Niche shifts occurred more frequently along variables that were of little ecological importance in the non-native range, and about 75 % of the shifts detected do not result from range expansion into different environments but only reflect climatic conditions at introduction locations. Excluding variables exhibiting a niche shift increases the accuracy of predictions of invasion risk generated by native-range based distribution models, evidencing that selection of variables is a crucial step when studying niche changes during biological invasions.  相似文献   

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D Owen 《CMAJ》1984,130(10):1341-1345
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Kamm FM 《Bioethics》1987,1(3):255-271
Kamm is concerned with explaining how "common sense" morality might be used in deciding about the distribution of scarce medical resources. Drawing an analogy between redirection of possible harms or threats and the allocation of health resources, she first explores how an ordinary moral agent, not a physician, might act. Using what Kamm calls the principle of irrelevant utilities (PIU), a moral agent might decide between contestants for a particular good based on "sobjectivism" (Sob), the author's term for a combination of the objective and subjective points of view. Kamm explores decision making using three versions of Sob that weigh interests and rights, equivalences, and aggregation of costs (losses). She concludes that, while ordinary moral agents functioning as social agents may act according to objective aggregated costs, physicians should be concerned with equivalents and individuals when allocating resources.  相似文献   

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Health care organization foundations and other fund-raising departments often function at an arm’s length from the system at large. As such, operations related to their mandate to raise funds and market the organization do not receive the same level of ethical scrutiny brought to bear on other arms within the organization. An area that could benefit from a more focused ethics lens is the use of language and rhetoric employed in order to raise funds and market the organization. Such departments and divisions often utilize overblown promises of miracles and extraordinary advances to convince donors to contribute and to persuade the general public. The result can be a heightened sense of expectation on the part of patients, their families, and the general public as to what can realistically be achieved by the health care system, leading to disappointment and conflict when these expectations are not or cannot be met. This article suggests that such advertising and marketing be subject to the same advertising standards as other businesses.  相似文献   

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In this paper I argue that we can learn much about ‘wild justice’ and the evolutionary origins of social morality – behaving fairly – by studying social play behavior in group-living animals, and that interdisciplinary cooperation will help immensely. In our efforts to learn more about the evolution of morality we need to broaden our comparative research to include animals other than non-human primates. If one is a good Darwinian, it is premature to claim that only humans can be empathic and moral beings. By asking the question ‘What is it like to be another animal?’ we can discover rules of engagement that guide animals in their social encounters. When I study dogs, for example, I try to be a ‘dogocentrist’ and practice ‘dogomorphism.’ My major arguments center on the following ‘big’ questions: Can animals be moral beings or do they merely act as if they are? What are the evolutionary roots of cooperation, fairness, trust, forgiveness, and morality? What do animals do when they engage in social play? How do animals negotiate agreements to cooperate, to forgive, to behave fairly, to develop trust? Can animals forgive? Why cooperate and play fairly? Why did play evolve as it has? Does ‘being fair’ mean being more fit – do individual variations in play influence an individual's reproductive fitness, are more virtuous individuals more fit than less virtuous individuals? What is the taxonomic distribution of cognitive skills and emotional capacities necessary for individuals to be able to behave fairly, to empathize, to behave morally? Can we use information about moral behavior in animals to help us understand ourselves? I conclude that there is strong selection for cooperative fair play in which individuals establish and maintain a social contract to play because there are mutual benefits when individuals adopt this strategy and group stability may be also be fostered. Numerous mechanisms have evolved to facilitate the initiation and maintenance of social play to keep others engaged, so that agreeing to play fairly and the resulting benefits of doing so can be readily achieved. I also claim that the ability to make accurate predictions about what an individual is likely to do in a given social situation is a useful litmus test for explaining what might be happening in an individual's brain during social encounters, and that intentional or representational explanations are often important for making these predictions.  相似文献   

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Small leaves and low specific leaf area (SLA) have long been viewed as adaptations to Mediterranean-type climates in many species of evergreen woody plants. However, paleobotanical and floristic evidence suggests that in many cases these traits originated prior to the advent of the summer-drought climate regime. In this study, molecular phylogenies and ancestral state reconstructions were used to test the hypothesis of adaptive leaf evolution in 12 lineages of evergreen shrubs in the California chaparral. Across all lineages there was a small but significant shift toward lower SLA, but there were no trends in leaf size evolution. For individual lineages, adaptive changes were detected in only three cases for SLA and in one case for leaf size. Three of these cases of evolutionary change were observed in taxa derived from cool temperate ancestors (e.g., Heteromeles). In contrast, most lineages originating from subtropical ancestors exhibited relative stasis in leaf trait evolution (e.g., Ceanothus). The absence of change suggests that ancestors of chaparral taxa had already acquired appropriate traits that contributed to their success under Mediterranean-type climates. These results illustrate how biogeographic history may influence patterns of trait evolution and adaptation and highlight the contribution of ecological sorting processes to the assembly and functional ecology of regional biotas.  相似文献   

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In this article I argue that the concern with gender relations and the challenges female activists were facing foreclosed any discussion of the transformation activism signalled for male comrades, and thus for wider society. I am particularly interested in men’s own views of their social roles and personal predicaments as the more subtle processes of transformation in the lives of male activists are often overlooked. The article takes a closer look at relationships between men, whether friendships or kin relations, as important roles and everyday practices former activists were/are involved in—during their phase of active participation, but crucially also before they become militants and in the aftermath of their involvement in the movement.  相似文献   

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The behavioral immune system (BIS) is a cluster of psychological mechanisms (e.g., disgust) that have evolved to promote disease-avoidance (Schaller M. (2006). Parasites, behavioral defenses, and the social psychological mechanisms through which cultures are evoked. Psychological Inquiry, 17, 96–101). Recent evidence suggests that the BIS may promote avoidance of outgroup members, an historical source of contamination, by evoking social conservatism (Terrizzi JA Jr, Shook NJ, & Ventis WL. (2010). Disgust: A predictor of social conservatism and prejudicial attitudes toward homosexuals. Personality and Individual Differences, 49, 587–592; Terrizzi J, Shook N, Ventis L. (2012). Religious conservatism: An evolutionarily evoked disease-avoidance strategy. Religion, Brain & Behavior, 2, 105120.). That is, the BIS mechanisms may encourage the endorsement of socially conservative beliefs, which promote social exclusivity, tradition, and negativity toward outgroups. The current study provides a systematic review and meta-analysis of 24 studies to evaluate the hypothesis that the BIS is predictive of social conservatism. The results indicate that behavioral immune strength, as indicated by fear of contamination and disgust sensitivity, is positively related to social conservatism (i.e., right-wing authoritarianism, social dominance orientation, religious fundamentalism, ethnocentrism, collectivism, and political conservatism). These findings provide initial evidence that socially conservative values may function as evolutionarily evoked disease-avoidance strategies.  相似文献   

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