Neutral Theory

The breakthroughs in microbiology have allowed us to come to terms with the microbial resources present in culture collections and in natural environments. The challenge at present is to manage these microbial resources, particularly when one deals with open systems where the dynamics of microbial ecology are predominant. Hence, to properly address the aspects of Microbial Resource Management (MRM), one needs to handle the questions of who is there, who is doing what with whom and how can one adjust, control and/or steer these mixed cultures and communities. It is argued that microbial ecologists and environmental microbiologists need to address a new mind-set. The Beijerinck axioma that all microorganisms are everywhere should not be presumed to be generally valid. The Darwin based niche assembly concept needs to be supplemented with the neutral theory of Hubbell. The Pareto 80/20 principle is also applicable to the macro-economies of microbial communities. Finally, the concept of a “stable” microbial community should be replaced by that of a cooperative community continuum. Overall, MRM is at the basis of a number of new developments in domains such as environmental safety and health, renewable energy production, closing environmental cycles and providing new materials. Specific examples such as, for example, pro-active immuno-stimulation by means of drinking water, electro-microbiology, decreasing global warming by implementation of methanotrophs and generation of nano-biocatalysts are discussed.

The “Neutral” is the structuralist term that asserts “neither A nor B.” Affirming two negatives, the Neutral places itself outside the range of given possibilities; this makes it a utopian form. Especially in The Neutral, Roland Barthes delights in displaying escapes from the wearying assertiveness of linguistic paradigms. Barthes’s Neutral offers utopian forms that are remarkably private: utopia becomes an epoch of rest away from worldliness. The spring of Barthes’s utopia is weariness; the shape of it is mysticism. One prominent form of Barthes’s utopia is Japan, a Japan that clashes with how Japan appears to his contemporary Edward Seidensticker, American scholar of Japanese whose impulses are antineutral. Seidensticker thus is Barthes’s foil, but nontheless emerges as an intriguing personality in his own right.

The contribution of deterministic and stochastic processes to species coexistence is widely debated. With the
introduction of powerful statistical techniques, we can now better characterise different sources of uncertainty
when quantifying niche differentiation. The theoretical literature on the effect of stochasticity on coexistence,
however, is often ignored by field ecologists because of its technical nature and difficulties in its application.
In this review, we examine how different sources of variability in population dynamics contribute to
coexistence. Unfortunately, few general rules emerge among the different models that have been studied to
date. Nonetheless, we believe that a greater understanding is possible, based on the integration of coexistence
and population extinction risk theories. There are two conditions for coexistence in the presence of
environmental and demographic variability: (1) the average per capita growth rates of all coexisting species must
be positive when at low densities, and (2) these growth rates must be strong enough to overcome negative
random events potentially pushing densities to extinction. We propose that critical tests for species coexistence
must account for niche differentiation arising from this variability and should be based explicitly on notions of
stability and ecological drift.

This paper focuses on highlighting out the way financial leverage has been approached, both from classic and modern perspective. Literature on financial leverage is reviewed in order to get a deeper insight on the way theories, concepts and mentalities have evolved. From the classic neutral theory according to which the value of the company is independent from its capital structure till the modern one which permits the company to support its growth potential by resorting to external financial resources, leverage was considered to be a key-element of the corporate financial management, especially in the context of the corporate governance mechanisms implementation. The last section contains a case-study made on the equipments section companies listed on Bucharest Stock Exchange in terms of leverage evolution.

This paper focuses on highlighting out the way financial leverage has been approached, both from classic and modern perspective. Literature on financial leverage is reviewed in order to get a deeper insight on the way theories, concepts and mentalities have evolved. From the classic neutral theory according to which the value of the company is independent from its capital structure till the modern one which permits the company to support its growth potential by resorting to external financial resources, leverage was considered to be a key-element of the corporate financial management, especially in the context of the corporate governance mechanisms implementation. The last section contains a case-study made on the equipments section companies listed on Bucharest Stock Exchange in terms of leverage evolution.

1Studies seeking to explain local patterns of diversity have typically relied on niche explanations, reflected in correlations with local environmental conditions, or neutral theory, invoking dispersal processes and speciation.2We used macroinvertebrate community data from 10 streams that varied independently in local ecological conditions and spatial proximity. Neutral theory predicts that similarity in communities will be negatively associated with distance between sites, while niche theory suggests that community similarity will be positively associated with similarity in local ecological conditions.3Similarity in total invertebrate, grazer and predator assemblages showed negative relationships with distance and, for grazers and predators, positive relationships with local ecological conditions. However, the best model predicting community similarity in all three cases included aspects of both local ecological conditions and distance between sites.4When assemblages were analysed according to dispersal ability, high-dispersal species were shown to be freely accessing all sites and community similarity was not well predicted by either local ecology or spatial separation. Assemblages of species with low and moderate dispersal ability were best predicted by combined models, including distance between sites and local ecological factors.5The results suggest that the perceived dichotomy between neutral and local environmental processes in determining local patterns of diversity may not be useful. Neutral and niche processes structured these communities differentially depending on trophic level and species traits.6We emphasize the potential for both dispersal processes and local environmental conditions to explain local patterns of diversity.Studies seeking to explain local patterns of diversity have typically relied on niche explanations, reflected in correlations with local environmental conditions, or neutral theory, invoking dispersal processes and speciation.We used macroinvertebrate community data from 10 streams that varied independently in local ecological conditions and spatial proximity. Neutral theory predicts that similarity in communities will be negatively associated with distance between sites, while niche theory suggests that community similarity will be positively associated with similarity in local ecological conditions.Similarity in total invertebrate, grazer and predator assemblages showed negative relationships with distance and, for grazers and predators, positive relationships with local ecological conditions. However, the best model predicting community similarity in all three cases included aspects of both local ecological conditions and distance between sites.When assemblages were analysed according to dispersal ability, high-dispersal species were shown to be freely accessing all sites and community similarity was not well predicted by either local ecology or spatial separation. Assemblages of species with low and moderate dispersal ability were best predicted by combined models, including distance between sites and local ecological factors.The results suggest that the perceived dichotomy between neutral and local environmental processes in determining local patterns of diversity may not be useful. Neutral and niche processes structured these communities differentially depending on trophic level and species traits.We emphasize the potential for both dispersal processes and local environmental conditions to explain local patterns of diversity.

Depuis la parution de L’origine des espèces en 1859, les évolutionnistes n’ont cessé de caractériser leurs théories comme « darwiniennes », « non darwiniennes », « antidarwiniennes ». Bien que ces termes soient notoirement ambigus, la référence répétée à Darwin a une signification théorique. Darwin a mis en place un cadre théorique contraignant qui a canalisé les recherches évolutionnistes. Ce cadre est reconstitué dans ses deux aspects originels : « descendance avec modification » et « sélection naturelle ». Dans les deux cas, on classe les critiques qu’ils ont suscitées et l’on compare les modèles particuliers que Darwin a donnés de ces deux versants de sa théorie à ceux qui en ont été donnés au cours des 50 dernières années. La descendance avec modification s’exprime chez Darwin dans un diagramme arborescent dont la forme a fait l’objet de trois principales critiques : refus de la représentation graduelle du changement, refus de généalogies qui concentrent le changement au seul niveau des espèces et réserves au sujet des diagrammes arborescents comme seul mode de représentation des généalogies. Quant à l’hypothèse sélection naturelle, elle a été critiquée et amendée aux deux niveaux de justification invoqués par Darwin : celui de la « simple hypothèse » et celui d’un principe explicatif unifiant l’ensemble des phénomènes constituant l’histoire de la vie. Au premier niveau, trois débats ont dominé les recherches du demi-siècle écoulé : théorie neutraliste de l’évolution moléculaire, sélection de groupe et contraintes de complexité. Au deuxième niveau, les évolutionnistes contemporains ont contesté l’affirmation de Darwin, selon laquelle la sélection naturelle était un principe théorique suffisant pour expliquer des classes de phénomènes, telles que les extinctions, la divergence, l’allure de la documentation fossile et de la classification. En conclusion, l’article examine les positions successives et ambivalentes que S.J. Gould a formulées quant au caractère « darwininien » ou « non darwinien », au sujet de la structure de la théorie contemporaine de l’évolution. Gould est passé de l’affirmation que le darwinisme était « mort », à une vision plus nuancée, dans laquelle il n’a pas été « remplacé », mais a vu ses principes fondamentaux remaniés, par « généralisation » et par « addition » de principes nouveaux. L’article conclut que le cadre théorique mis en place par Darwin s’est maintenu, non au sens des modèles particuliers que Darwin avait mis en place, mais au sens de postulats heuristiques qui ont contraint l’espace des choix théoriques possibles.The article examines why evolutionary biologists have been haunted by the question whether they are “Darwinian” or “non-Darwinian” ever since Darwin's Origin of species. Modern criticisms addressed to Darwinism are classified into two categories: those concerning Darwin's hypothesis of “descent with modification” and those addressed to the hypothesis of natural selection. In both cases, although the particular models that Darwin proposed for these two hypotheses have been significantly revised and expanded, Darwin's general framework has constrained and canalized evolutionary research, in the sense that it has settled an array of possible theoretical choices. Gould's changing attitudes regarding Darwinism is taken as a striking illustration of this interpretation.

The origin of diversification and coexistence of genes and species have been traditionally studied in isolated biological levels. Ecological and evolutionary views have focused on the mechanisms that enable or constrain species coexistence, genetic variation and the genetics of speciation, but a unified theory linking those approaches is still missing. Here we introduce evolutionary graphs in the context of neutral theories of molecular evolution and biodiversity to provide a framework that simultaneously addresses speciation rate and joint genetic and species diversities. To illuminate this question we also study two models of evolution on graphs with fitness differences, which provide insights on how genetic and ecological dynamics drive the speed of diversification. Neutral evolution generates the highest speed of speciation, species richness (i.e. five times and twice as many species as compared to genetic and ecological graphs, respectively) and genetic--species diversity (i.e....

I argue that evolutionary strategies of kin selection and game-theoretic reciprocity are apt to generate agent-centered and agent- neutral moral intuitions, respectively. Such intuitions are the building blocks of moral theories, resulting in a fundamental schism between agent-centered theories on the one hand and agent-neutral theories on the other. An agent-neutral moral theory is one according to which everyone has the same duties and moral aims, no matter what their personal interests or interpersonal relationships. Agent-centered moral theories deny this and include at least some prescriptions that include ineliminable indexicals. I argue that there are no rational means of bridging the gap between the two types of theories; nevertheless this does not necessitate skepticism about the moral—we might instead opt for an ethical relativism in which the truth of moral statements is relativized to the perspective of moral theories on either side of the schism. Such a relativism does not mean that any ethical theory is as good as any other; some cannot be held in reflective equilibrium, and even among those that can, there may well be pragmatic reasons that motivate the selection of one theory over another. But if no sort of relativism is deemed acceptable, then it is hard to avoid moral skepticism.

The question ''Why did they do it?'' is central to the criminologist's quest, and posing it to offenders themselves has been a part of criminology since its origins (see esp. Bennett 1981). Perhaps the best known response is the account that makes up Clifford Shaw's The Jack-Roller: A ...

The neutral model of biodiversity, proposed by Hubbell (The Unified Neutral Theory of Biodiversity and Biogeography, Princeton University Press, Princeton, NJ, 2001) to explain the diversity of functionally equivalent species, has been subject of hot debate in community ecology. Whereas Hubbell studied the model mostly by simulations, recently analytical treatments have yielded expressions of the expected number of species of a particular abundance in a local community with dispersal limitation. Moreover, a formula has been offered for the joint likelihood of observing a given species-abundance dataset in a local community with dispersal limitation, but this formula is too complicated to allow practical applications. Here, I present a much simplified expression that can be regarded as an enhanced version of the famous Ewens sampling formula. It can be used in maximum likelihood methods for quick estimation of the model parameters, using all information in the data, and for model comparison. I also show how to rapidly generate examples of species-abundance distributions for a given set of model parameters and how to calculate Simpson's diversity index.

A central issue in ecology today is that of the factors determining the relative abundance of species within a natural community. The proper application of the principles of statistical physics to the problem of species abundance distributions (SADs) has enabled us to identify the fundamental ecological principles responsible for the near universal features observed. These principles are (i) a limit

Aim It is a central issue in ecology and biogeography to understand what governs community assembly and the maintenance of biodiversity in tropical rain forest ecosystems. A key question is the relative importance of environmental species sorting (niche assembly) and dispersal limitation (dispersal assembly), which we investigate using a large dataset from diverse palm communities.