共查询到20条相似文献,搜索用时 46 毫秒
1.
A. Gardner 《Journal of evolutionary biology》2015,28(9):1747-1751
In my article The genetical theory of multilevel selection, I provided a synthesis of the theory of multilevel selection (MLS) and the theory of natural selection in class‐structured populations. I framed this synthesis within Fisher's genetical paradigm, taking a strictly genetical approach to traits and fitness. I showed that this resolves a number of long‐standing conceptual problems that have plagued the MLS literature, including the issues of ‘aggregate’ vs. ‘emergent’ group traits, ‘collective fitness1’ vs. ‘collective fitness2’ and ‘MLS1’ vs. ‘MLS2 ‘. In his commentary, Goodnight suggests this theoretical and conceptual synthesis is flawed in several respects. Here, I show this is incorrect, by: reiterating the theoretical and conceptual goals of my synthesis; clarifying that my genetical approach to traits is necessary for a proper analysis of the action of MLS independently of non‐Darwinian factors; emphasizing that the Price–Hamilton approach to MLS provides a consistent, useful and conceptually superior theoretical framework; and explaining the role of reproductive value in the study of natural selection in class‐structured populations. I also show that Goodnight's contextual analysis treatment of MLS in a class‐structured population is mathematically, biologically and conceptually inadequate. 相似文献
2.
Beauty in the eyes of the beholders: colour vision is tuned to mate preference in the Trinidadian guppy (Poecilia reticulata)
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A broad range of animals use visual signals to assess potential mates, and the theory of sensory exploitation suggests variation in visual systems drives mate preference variation due to sensory bias. Trinidadian guppies (Poecilia reticulata), a classic system for studies of the evolution of female mate choice, provide a unique opportunity to test this theory by looking for covariation in visual tuning, light environment and mate preferences. Female preference co‐evolves with male coloration, such that guppy females from ‘low‐predation’ environments have stronger preferences for males with more orange/red coloration than do females from ‘high‐predation’ environments. Here, we show that colour vision also varies across populations, with ‘low’‐predation guppies investing more of their colour vision to detect red/orange coloration. In independently colonized watersheds, guppies expressed higher levels of both LWS‐1 and LWS‐3 (the most abundant LWS opsins) in ‘low‐predation’ populations than ‘high‐predation’ populations at a time that corresponds to differences in cone cell abundance. We also observed that the frequency of a coding polymorphism differed between high‐ and low‐predation populations. Together, this shows that the variation underlying preference could be explained by simple changes in expression and coding of opsins, providing important candidate genes to investigate the genetic basis of female preference variation in this model system. 相似文献
3.
Companion plants grown as ‘trap crops’ or ‘intercrops’ can be used to reduce insect infestations in field crops. The ways in which such reductions are achieved are being described currently using either a chemical approach, based on the ‘push‐pull strategy’, or a biological approach, based on the ‘appropriate/inappropriate landing theory’. The chemical approach suggests that insect numbers are reduced by chemicals from the intercrop ‘repelling’ insects from the main crop, and by chemicals from the trap‐crop ‘attracting’ insects away from the main crop. This approach is based on the assumptions that (1) plants release detectable amounts of volatile chemicals, and (2) insects ‘respond’ while still some distance away from the emitting plant. We discuss whether the above assumptions can be justified using the ‘appropriate/inappropriate landing theory’. Our tenet is that specialist insects respond only to the volatile chemicals released by their host plants and that these are released in such small quantities that, even with a heightened response to such chemicals, specialist insects can only detect them when a few metres from the emitting plant. We can find no robust evidence in the literature that plant chemicals ‘attract’ insects from more than 5 m and believe that ‘trap crops’ function simply as ‘interception barriers’. We can also find no evidence that insects are ‘repelled’ from landing on non‐host plants. Instead, we believe that ‘intercrops’ disrupt host‐plant finding by providing insects with a choice of host (appropriate) and non‐host (inappropriate) plant leaves on which to land, as our research has shown that, for intercropping to be effective, insects must land on the non‐host plants. Work is needed to determine whether non‐host plants are repellent (chemical approach) or ‘non‐stimulating’ (biological approach) to insects. 相似文献
4.
Island biogeography theory, created initially to study diversity patterns on islands, is often applied to habitat fragments. A key but largely untested assumption of this application of theory is that landscape matrix species composition is non‐overlapping with that of the islands. We tested this assumption in successional old field patches in a closely mowed matrix, and because our patches are appropriately viewed as sets of contiguous habitat units we studied patterns of species richness per unit area. Previous studies at our site did not find that diversity patterns on patch ‘islands’ conformed to predictions of island biogeography theory. Our results indicate that when matrix species are removed from the patch samples, diversity patterns conform better to theory. We suggest that classical island theory remains an appropriate tool to study diversity patterns in fragmented habitats, but that allowances should be made for spill‐over colonization of ‘islands’ from the ‘sea’. 相似文献
5.
Jeremy W. Fox 《Ecology letters》2005,8(8):846-856
Experimental ecosystems often function differently than expected under the null hypothesis that intra‐ and interspecific interactions are identical. Recent theory attributes this to the ‘selection effect’ (dominance by species with particular traits), and the ‘complementarity effect’ (niche differentiation and/or facilitative interactions). Using the Price Equation, I show that the ‘selection effect’ only partially reflects dominance by species with particular traits at the expense of other species, and therefore is only partially analogous to natural selection. I then derive a new, tripartite partition of the difference between observed and expected ecosystem function. The ‘dominance effect’ is analogous to natural selection. ‘Trait‐independent complementarity’ occurs when species function better than expected, independent of their traits and not at the expense of other species. ‘Trait‐dependent complementarity’ occurs when species with particular traits function better than expected, but not at the expense of other species. I illustrate the application of this new partition using experimental data. 相似文献
6.
Michael Goddard 《The Australian journal of anthropology》2013,24(2):131-147
Courts of law in Melanesian countries, particularly in the aftermath of the colonial period, have attempted to accommodate ‘custom’. In Papua New Guinea they commonly hear land claims under terms of reference that acknowledge the wide variety of customs among the many ethno‐linguistic groups comprising the nation. A corollary of this liberalism is that, in theory, they admit ‘traditional evidence’ including legends and myths. Yet as courts of law they are required to apply some criteria of proof and to search for the ‘truth’ by examining the ‘facts’. A long‐running land case from Papua New Guinea and its aftermath raises interesting questions about what happens when oral history encounters these legal imperatives, and may help us appreciate why Melanesians often do not regard a court's decision as final. 相似文献
7.
doi:10.1111/j.1741‐2358.2009.00306.x Understanding the ‘epidemic’ of complete tooth loss among older New Zealanders Objective: The aim of this study was to obtain a deeper understanding of the social factors driving New Zealand’s historic ‘epidemic of edentulism’ and how they operated. Method: In‐depth, semi‐structured interviews with 31 older New Zealanders were analysed using applied grounded theory. Results: Universal factors present in the data were: (a) the way in which New Zealand society accepted and indeed encouraged edentulism without stigma for those who had a ‘sub‐optimal’ natural dentition; (b) how the predominant patterns of dental care utilisation (symptomatic and extraction‐based) were often strongly influenced by economic and social disadvantage; and (c) the way in which lay and professional worldviews relating to ‘calcium theory’ and dental caries were fundamental in decisions relating to the transition to edentulism. Major influences were rural isolation, the importance of professional authority and how patient‐initiated transitions to edentulism were ultimately facilitated by an accommodating profession. Conclusion: The combined effects of geography, economics, the dental care system and the professional culture of the day, in the context of contemporary (flawed) understandings of oral disease, appear to have been the key drivers. These were supported (in turn) by a widespread acceptance by the profession and society alike of the extraction/denture philosophy in dealing with oral disease. 相似文献
8.
Ma Shu Yun 《Ethnic and racial studies》2013,36(4):527-541
Some terms have been coined to highlight the important relation between nationalism and ethnicity. However, there has been much confusion as to the meaning of such concepts as ‘ethnonationalism’, ‘ethnic nationalism’ and ‘mini‐nationalism’. This article compares the three terms, as used respectively in the works of Walker Connor, Anthony Smith and Louis Snyder. These scholars are selected not only because of their well‐respected position in the study of nationalism but also because their works are representative of each of the three concepts. The comparison finds that since both Connor and Smith emphasized the ethnic dimension of nationalism, their ideas can be presented in one analytical framework. In fact, Connor's ‘ethnonationalism’ and Smith's ‘ethnic nationalism’ overlap with each other. However, Smith's theory of nationalism is comprehensive enough to take care of the fact that the nationalisms of many new states of today's world have no ethnic base at all, whereas Connor's analysis makes no mention of this. In this respect, Smith's model is preferred to that of Connor. Finally, Snyder's ‘mini‐nationalism’ is seen as the least useful concept, since the use of size rather than ethnicity to classify nationalisms does not increase our understanding of the concept. 相似文献
9.
Although possession is ‘nine‐tenths of the law’, respect for ownership is widespread in the animal kingdom even without third‐party enforcement. Thus, the first individuals to find objects are frequently left unchallenged by potential competitors and tend to win contests when disputes arise. Game theory has shown that respect for ownership (‘Bourgeois’ behaviour) can arise as an arbitrary convention to avoid costly disputes. However, the same theory predicts that a paradoxical respect for lack of ownership (‘anti‐Bourgeois’ behaviour) can evolve under the same conditions and in some cases is the only stable outcome. Despite these predictions, anti‐Bourgeois behaviour is rare in nature, whereas respect for ownership is frequently not absolute. Here, we review extensions of the classic models involving repeated interactions, confusion over roles, strategic coordination of behaviour (‘secret handshakes’), owner–intruder asymmetries and continuous control of fighting investment. Confusion over roles and owner–intruder asymmetries in fighting ability may explain why respect for ownership is often partial. Moreover, although most model extensions facilitate the evolution of Bourgeois‐like behaviour, secret handshakes and continuous control of fighting investment render the alternative anti‐Bourgeois convention unstable. We develop these insights to highlight several key areas for future investigation. 相似文献
10.
Ann McGregor Brian Coffey Carrie Deutsch Geoff Wescott Jim Robinson 《Ecological Management & Restoration》2011,12(3):194-199
Summary Developments in ecological theory indicate that ecological processes have major implications for sustaining biodiversity and the provision of ecosystem services. Consequently, conservation actions that focus solely on particular species, vegetation communities, habitats or sites (‘assets’) are unlikely to be effective over the long term unless the ecological processes that support them continue to function. Efforts to sustain biodiversity must embrace both ‘assets’ and ‘process‐oriented’ approaches. Existing knowledge about ecological processes, incomplete though it is, has not been adequately considered in government decision making. It is, therefore, necessary to consider how to build consideration of ecological processes into legislative and institutional frameworks, policy and planning processes, and on‐ground environmental management. Drawing on insights from interviews, a facilitated workshop, and a literature review, this paper identifies a suite of policy priorities and associated reforms which should assist in ensuring that ecological processes are given more attention in policy‐making processes. It is concluded that a multi‐pronged approach is required, because there are no ‘silver bullets’ for sustaining ecological processes. 相似文献
11.
Unravelling the Philosophies Underlying ‘Animal Personality’ Studies: A Brief Re‐Appraisal of the Field
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The last decade has seen lots of studies on ‘animal personality’ (i.e. the study of consistent between‐individual behavioural differences). As timely and promising as this field is, its development has come with a diversity of research questions. As an unfortunate consequence, it now suffers from substantial confusion about what ‘animal personality’ is, and how relevant related research frameworks are. Here, we stress the current inconsistencies and sources of confusion pertaining to the field, and their consequences on terminology used and miscommunication between researchers. In an attempt to unravel and clarify the concepts underlying the field, we identify two distinct, but complementary, theory‐driven conceptual frameworks: the intra‐individual variability (IIV) approach and the life‐history (LH) approach, which we believe encompass the vast majority of existing ‘personality studies’. Finally, we argue in favour of theory‐driven studies of consistent behavioural differences and state that the integrative statistical properties of random regression models should not override the merit of alternative conceptual frameworks. We then provide brief guidelines and warnings for a parsimonious and sound use of terminology. 相似文献
12.
MARGARET A. CLIFF MIKE O'MAHONY LANA FUKUMOTO MARJORIE C. KING 《Journal of sensory studies》2000,15(2):219-229
A new ‘bipolar’ R‐index analysis was proposed and evaluated. Eighteen judges evaluated red color in eight wine samples by comparing each sample with the control. Judges indicated whether the sample had ‘more’, the 'same’, or ‘less’ red color than the control, and whether they were sure or unsure of their decision. Three computational methods were used to examine the results: the ‘traditional’ R‐index, the ‘bipolar’ R‐index (Rmore or Rless) and the ‘weighted‐bipolar’ R‐index. While all three methods provided consistent results, the ‘bipolar’ R‐indices reflected bidirectional differences among the samples thus providing more information. A refinement to the computation (‘weighted‐bipolar’ R‐index) was an approach for eliminating the bias associated with overestimation of the sample size and accordingly changed some of the significance levels. Further research is currently underway to expand the scope and application of this method. 相似文献
13.
Drought limitations to leaf‐level gas exchange: results from a model linking stomatal optimization and cohesion–tension theory
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We merge concepts from stomatal optimization theory and cohesion–tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf‐level gas exchange in trees during drought: (1) a ‘demand limitation’ driven by an assumption of optimal stomatal functioning; (2) ‘hydraulic limitation’ of water movement from the roots to the leaves; and (3) ‘non‐stomatal’ limitations imposed by declining leaf water status within the leaf. Model results suggest that species‐specific ‘economics’ of stomatal behaviour may play an important role in differentiating species along the continuum of isohydric to anisohydric behaviour; specifically, we show that non‐stomatal and demand limitations may reduce stomatal conductance and increase leaf water potential, promoting wide safety margins characteristic of isohydric species. We used model results to develop a diagnostic framework to identify the most likely limiting mechanism to stomatal functioning during drought and showed that many of those features were commonly observed in field observations of tree water use dynamics. Direct comparisons of modelled and measured stomatal conductance further indicated that non‐stomatal and demand limitations reproduced observed patterns of tree water use well for an isohydric species but that a hydraulic limitation likely applies in the case of an anisohydric species. 相似文献
14.
Tor Engeström 《Ethnos》2013,78(1-2):64-69
’Cultural theory’, launched by social anthropologist Mary Douglas, has been highly influential in the inter‐disciplinary field concerned with the study of risk perception and risk communication. The theory derives from the grid‐group analyses that Douglas developed in the 1970s. Cultural theory aims to explain universal ‘cultural bias’ by way of a general typology of group formation and a concomitant cosmology or world view. This article critically examines cultural theory and the study of hazards as culturally construed phenomena. 相似文献
15.
T. Frede Thingstad Lise Øvreås Jorun K. Egge Trond Løvdal Mikal Heldal 《Ecology letters》2005,8(7):675-682
Coexistence of two organisms competing for the same nutrient is possible if one is an ‘uptake’, and the other a ‘predation defence’ specialist. In pelagic food webs this principle has been linked to cell size. Small osmotroph cells, with their high surface : volume ratio, have been argued to be uptake specialists, while larger osmotrophs avoiding the intense grazing pressure from small protozoan predators might represent ‘predation defence’ specialists. This may seem like an obligatory trade‐off situation that necessitates a choice of either being small or being large, and thus being potentially dominant in oligotrophic or in eutrophic environments, respectively. However, in a more precise form, the theory for nutrient diffusion states that it is the ‘surface : cell requirement of limiting element’ ratio, rather than the ‘surface : volume’ ratio, that is important. The distinction is crucial, since it opens up the possibility of there being life strategies that use a non‐limiting element to increase size. Hypothesized to maximize uptake and predator defence simultaneously, such strategies should be particularly successful. We suggest that this strategy is exploited by osmotrophs with different size and physiology, such as heterotrophic bacteria, unicellular cyanobacteria and diatoms. Since the strategy implies a shift in organism stoichiometry, the biogeochemical implications are strong, illustrating the tight relationships between physical micro‐scale processes, organism life strategies, biodiversity, food web structure, and biogeochemistry. 相似文献
16.
Richard J. Martin David Trigger 《The journal of the Royal Anthropological Institute》2015,21(2):276-295
This article focuses on human‐plant relations, drawing on ethnographic research from northern Australia's Gulf Country to address the concept of indigeneity. Just as the identities of ‘Indigenous’ and ‘non‐Indigenous’ people in this region are contextual and at times contested according to the vernacular categories of ‘Blackfellas’, ‘Whitefellas’, and ‘Yellafellas’, so too the issue of what ‘belongs’ in the natural world is negotiated through ambiguities about whether species are useful, productive, and aesthetically pleasing to humans, as well as local understandings about how plants and animals came to be located in the Gulf region. At the same time, plants’ distinctive characteristics as plants shape their relations with humans in ways which affect their categorization as ‘native’ and ‘alien’ or ‘introduced’. Focusing our analysis on three specific trees, we argue that attention to the ‘plantiness’ of flora contributes significantly to debates about indigeneity in society and nature. At the same time, our focus on human‐plant relations contributes important context and nuance to current debates about human and other‐than‐human relations in a more‐than‐human world. 相似文献
17.
C. Blut J. Wilbrandt D. Fels E.I. Girgel K. Lunau 《Entomologia Experimentalis et Applicata》2012,143(3):231-244
Many species of lepidoptera bear conspicuous circular patterns on their wings, known as eyespots, that are hypothesised to protect their bearers against predatory birds. In this study, we focus on a small but ubiquitous feature occurring naturally in lepidopteran eyespots, namely the so‐called ‘sparkle’. The ‘pupil’ in an eyespot is often highlighted by a ‘sparkle’, which is hypothesised to mimic a natural corneal total light reflection evident as a highlight, twinkle, or sparkle in the vertebrate eye. In a study exploring the presence of such sparkles, we found that 53% of lepidopteran eyespots exceeding 1 mm in diameter have a central, pinpoint‐like ‘sparkle’, 12% have a marginal, crescent‐shaped ‘sparkle’, 13% have a semi‐circular ‘sparkle’, and 22% have an intermediate semi‐circular to crescent‐shaped ‘sparkle’. In the lepidopterans’ natural resting position, the marginal ‘sparkles’ are positioned in the upper part of the eyespots’‘pupil’ and thus may create the illusion of a spherical eyeball. The ‘sparkles’ in lepidopteran eyespots do not only appear white to humans, but also reflect ultraviolet light. White and UV‐reflecting ‘sparkles’ also appear ‘white’ for UV‐sensitive viewers such as birds, and thus may effectively mimic the natural highlight in vertebrate eyes as an area of total light reflection. In field experiments using lepidopteran dummies baited with a mealworm, we show that the ‘sparkle’ is one of several components of eyespots eliciting a deterrent effect and that eyespots with a ‘sparkle’ in a natural position have a stronger deterrent effect than those with a ‘sparkle’ in an unnatural position. These findings support the eye mimicry hypothesis that better vertebrate eye mimicry improves the deterrent effect of eyespots. 相似文献
18.
P. Steven Sangren 《The journal of the Royal Anthropological Institute》2013,19(2):279-299
This article revisits well‐travelled ethnographic portrayals of traditional Chinese family dynamics to draw attention to desire as a product of family life and to how crucial elements of family organization and ideology can be understood, in turn, as effects of desire – that is, as instituted fantasies. Although my case in point is the Chinese family, the analysis addresses the category ‘family’ cross‐culturally. In any of its variations, the ‘family’ exists at two synergistically implicated levels: first, it comprises an important part of the reality into which individuals are socialized; second, it embodies in instituted form individuals' attempts to realize – to bring into being – social arrangements as they would like them to be. In the Chinese case, at least two ironies are embedded in this synergy. First, women are primary producers and reproducers of the family in the ‘real world’, despite the fact that patriliny as ‘instituted fantasy’ downplays or veils their agency. Second, the normative subordination of the son to a patriarchal father, expressed and mediated through institutions including ancestor worship and valorization of filial piety, veils a valorizing of the son as agent or protagonist of filial action. Although ultimately unrealizable, patrilineal and familial fantasies animate Chinese family life and are thus an important constituent of Chinese realities. To these ends the analysis re‐purposes ‘the symbolic’ and ‘imaginaries’, categories widely employed in contemporary gender studies and social theory, arguing that understanding kinship enjoins incorporating desire's role both in defining institutions and in motivating their creators. 相似文献
19.
Not a German past to be reckoned with: negotiating migrant subjectivities between Vergangenheitsbewältigung and the nationalization of history
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Alice von Bieberstein 《The journal of the Royal Anthropological Institute》2016,22(4):902-919
In discussing the public commemoration of the Armenian genocide and the case of a Turkish refugee‐turned‐memory‐activist in Germany, this article focuses on migrants as they mediate political concerns by reference to the German discourse and practice of Vergangenheitsbewältigung (confronting the past). Such engagements shed light on the intersection of a performative and inclusionary dimension of citizenship inscribed in the figure of the repentant perpetrator and the continuous re‐ethnicization of subjects by reference to particular nationalized histories. The analysis thus reveals the ‘memorial’ contour of a normative German citizen‐subject, one that is self‐reflexive vis‐à‐vis his or her national past. The article charts how the politics of history and citizenship thus play out at the level of subjectivity, implicating registers of affect and aesthetics that are not captured by the more commonly employed framework of ‘memory’, which falls short of analytical import precisely because it lacks a theory of the subject. 相似文献
20.
Herbert J. Gans 《Ethnic and racial studies》2013,36(2):173-192
‘Second‐generation decline’ questions the current American faith in the myth of nearly automatic immigrant success. In discussing economic scenarios, positive and negative, for the future of the children of the post‐1965 immigrants, the possibility is proposed that a significant number of the children of poor immigrants, especially dark‐skinned ones, might not obtain jobs in the mainstream economy. Neither will they be willing ‐ or even able ‐ to take low‐wage, long‐hour ‘immigrant’ jobs, as their parents did. As a result, they (and young males among them particularly) may join blacks and Hispanics among those already excluded, apparently permanently, from the mainstream economy. The article also deals with the relations between ethnicity and economic conditions in the USA and with the continued relevance of the assimilation and acculturation processes described by ‘straight‐line theory’. This issue, as well as most others discussed, may also be salient for European countries experiencing immigration, especially those countries with troubled economies. 相似文献