A Biosemiotic Perspective of the Resource Criterion: Toward a General Theory of Resources

Describing resources and their relationships with organisms seems to be a useful approach to a ‘unified ecology’, contributing to fill the gap between natural and human oriented processes, and opening new perspectives in dealing with biological complexity. This Resource Criterion defines the main properties of resources, describes the mechanisms that link them to individual species, and gives a particular emphasis to the biosemiotic approach that allows resources to be identified inside a heterogeneous ecological medium adopting the eco-field model. In particular, this Criterion allows to couple matter, structured energy and information composing the ecological systems to the biosemiotic and cognitive mechanisms adopted by individual species to track resources, transforming neutral surroundings into meaningful species-specific Umwelten. The expansion of the human semiotic niche that is a relevant evolutionary process of the present time, assigns the role of powerful and efficient agency to the Resources Criterion to evaluate the effect of human intrusion into the natural systems with habits of key stone species, under the challenge of a growing use of alloctonous, immaterial and symbolic resources of the actual globalized societal models. The Resource Criterion interprets the ecological dynamics contributing to complete the epistemology of the ecology, to open a bridge toward economy and other societal sciences, and to contribute to formulate a General Theory of Resources.     

Two Decades of Homage to Santa Rosalia: Toward a General Theory of Diversity

In 1959, in his seminal paper "Homage to Santa Rosalia," G.E. Hutchinson asked, Why are there so many kinds of organisms?This paper focused attention on problems of species diversityand community organization that have occupied many theoreticaland empirical ecologists for the last two decades. In the presentpaper I evaluate the attempt to answer Hutchinson's questionby considering three topics. First, I reexamine the main themeswhich Hutchinson developed in "The Homage" and call attentionto the central importance of energetic relationships in hisview of ecological communities. Second, I examine the developmentof theoretical community ecology over the last two decades inan attempt to determine why some avenues of investigation, suchas competition theory, have proven disappointing, whereas others,such as the theory of island biogeography, have enjoyed at leastmodest success. Finally, I suggest that future attempts to understandpatterns of species diversity might focus on developing twokinds of theoretical constructs: capacity rules, which describehow characteristics of the physical environment determine itscapacity to support life, and allocation rules, which describehow limited energetic resources are subdivided among species.     

Neuronal Control of Mucus Secretion by Leeches: Toward a General Theory for Serotonin

The large Retzius cells are serotonin-containing neurons whoseimpulse activity controls the secretion of mucus from the skinof leeches. Serotonin elicits the secretion of mucus withoutany apparent synaptic transfers in either the central or peripheralnervous systems. Such a secretogogue function may be more generalas serotonin controls the secretion of mucus from the gastrointestinaltract of mammals and from the ciliated gills of bivalved molluscs.Furthermore, the qualitative and quantitative distribution ofserotonin in molluscs, annelids, arthropods, and vertebratescorresponds approximately with mucosecretory structures. Serotoninappears also to control other secretory functions in some ofthese animals. It is proposed therefore that serotonin mightoften function in controlling secretion.     

The Precultural Basis of the Incest Taboo: Toward a Biosocial Theory

The literature on the origins of the incest taboo is characterized by controversy over the nature/nurture issue, and fears of reductionism. In recent years work emanating from such diverse disciplines as cultuml and physical anthropology, ethology, and neuropsychology warmnts a new look at this intriguing issue. It is probable that incest avoidance is widespread among the vertebrata and is built into the wiring. As learned behavior becomes more important phylogenetically, curiosity and exploration plays a larger role in adaptation and has manifest survival admntages. Incest awidance functions as a mechanism to propel the individual into new relationships and social territory. For humans, incest avoidance and its later elaboration into a cultuml taboo serve to motivate exploration of and attachment to a wider social nexus than the family. It also prevents fixation at a relatively undifferentiated psychological stage of development     

通用选择指数原理

本文在对各类种畜评定方法探讨的基础上,提出了通用选择指数概念,对各类评定方法在理论上加以综合,推导出统一的计算公式,并编制出相应的计算程序。为充分利用种畜各种信息,特别是为在多信息来源需作约束、最宜选择时的种畜评定,提供了行之有效的计算方法。避免了在实际应用时对各类评定方法的独立探讨以及因多种计算体系导致应用上的混乱。此外,本文还得出了有关选择理论的三个结论,并改正了文献[2]中的失误之处。     

Toward a Prehistory of the Na-Dene, with a General Comment on Population Movements among Nomadic Hunters

C. E. Borden has hypothesized that ancestral speakers of Na-Dene spread from Alaska to the Pacific Northwest by 5000 B.C. Based upon distributions of language and artifacts, two additional hypotheses are added here: (1) Once established from Alaska through British Columbia, Na-Dene people provided the means for the spread of side-notched projectile blades from the continental United States to Alaska before 4000 B.C. (2) After the Hypsithermal a further dispersal south and east from Alaska spread the specifically Athapaskan languages. It is further suggested that the spread of relatively nomadic hunters into country inhabited by their own linguistic and cultural relatives may be a regular and periodic occurrence.     

Thoughts Toward a Theory of Natural Selection: The Importance of Microbial Experimental Evolution

Natural selection should no longer be thought of simply as a primitive (magical) concept that can be used to support all kinds of evolutionary theorizing. We need to develop causal theories of natural selection; how it arises. Because the factors contributing to the creation of natural selection are expected to be complex and intertwined, theories explaining the causes of natural selection can only be developed through the experimental method. Microbial experimental evolution provides many benefits that using other organisms does not. Microorganisms are small, so millions can be housed in a test tube; they have short generation times, so evolution over hundreds of generations can be easily studied; they can grow in chemically defined media, so the environment can be precisely defined; and they can be frozen, so the fitness of strains or populations can be directly compared across time. Microbial evolution experiments can be divided into two types. The first is to measure the selection coefficient of two known strains over the first 50 or so generations, before advantageous mutations rise to high frequency. This type of experiment can be used to directly test hypotheses. The second is to allow microbial cultures to evolve over many hundreds or thousands of generations and follow the genetic changes, to infer what phenotypes are selected. In the last section of this article, I propose that selection coefficients are not constant, but change as the population becomes fitter, introducing the idea of the selection space.This article is about natural selection. For many years, I have asked my undergraduate students to memorize this definition of natural selection: Natural selection is the differential reproduction and survival of different phenotypes when, at least, part of the differences in phenotypes is caused by differences in genotype. This can also be expressed as differential growth rates of subpopulations when the subpopulations are distinguished by genetic differences. When expressed as differences in the growth rates in terms of the Malthusian growth parameter, m, then natural selection is the difference in birth rates minus the difference in death rates.From demography, we know that birth rates are very variable depending on the environment. In humans in the United States, the birth rate dropped during the economic depression of the 1930s, rose after World War II to produce a baby boom, and dropped afterward. Worldwide, birth rates drop with the provision of government-provided old-age assistance, also with the increasing survival of children previously born. Thus, birth rates are very sensitive to many environmental conditions. Likewise for death rates. We have long known that starvation, disease, war, and fratricide will increase the death rate, often dramatically. There has been a drop in death rates since 1750 as transportation and social organization improved, preventing starvation in local areas as the crops failed. The 1918 flu spiked the death rate and disease could again raise the death rate dramatically. The black plague is famous for wiping out a third to half of some European populations and changing social conditions. Today, high fructose sweetener is blamed for increasing the death rate among lower class Americans. Thus, the environment changes birth and death rates, sometimes dramatically, sometimes very subtly.Turning back to natural selection, natural selection is the difference between two subpopulations, defined by a genetic difference in their birth and death rates weighted by the effects of all environments experienced by these subpopulations over the time period of the observation. Will natural selection be even more complex than population demography or will it be simpler? It could be much more complicated because the response of the birth and death rates of the two subpopulations in the different environments could be different, giving different norms of reaction. Also, the epistasis and dominance could make the reactions of various individuals within each subpopulation to the changing environment very different. Or it could be much simpler when the genetic difference gives different effects only in one environment. For example, continued synthesis of the lactase gene is selected in human populations that ingest lactose as adults.This complexity embedded in the concept of natural selection has been known for a long time. In population genetics, it is assumed that one can estimate an average selection coefficient over all the environments experienced by the population in a set period without needing to specify the environments or their effect on birth and death rates. This selection coefficient is then used to project gene frequency change over time. Because population genetics is interested in the effects or consequences of natural selection, not the causes, it is satisfactory to treat natural selection as a constant without understanding the causes of natural selection. Unfortunately, this simplification has led to a caricature of natural selection as a constant, given a genetic difference.The model of natural selection that I currently use is given in Figure 1. Here, the definition of natural selection as I gave to my students is an expanded definition because phenotypes are generated by genotypes in an environment (the epigenetic environment) and natural selection is generated by differences in phenotypes in an environment (the selective environment). The interaction of genetic variation, epigenetic environment, phenotypic variation, and the selective environment generate natural selection. These are the “causes” of natural selection. The “effects” of natural selection produce changes in allele frequencies giving rise to adaptive evolution. I believe that the most important function of experimental evolution will be to figure out the causal rules or laws of natural selection. I have previously made the analogy of natural selection evolution with force in physics (Dykhuizen 1995). Newton described the effects of force; the understanding of the causes of force were performed over the next 300 years leading to an understanding of electromagnetism, thermodynamics, atomic energy, etc. This understanding has led to most of the practical applications from physics. Hopefully, the same can be performed for natural selection. But, as the causes of force were much stranger than expected, the causes of natural selection will be stranger than we now imagine. Only by doing experiments will we be forced to accept whatever strangeness there is in natural selection.Open in a separate windowFigure 1.The current model of natural selection indicating the complexity of its causes and distinguishing causes from effects. Population genetics studies only the effects of natural selection.     

On the Limits of Life Stages in Ethnography: Toward a Theory of Vital Conjunctures

This article argues for a new anthropology of the life course, one founded in indeterminacy and innovation. The fact that vital life events are rarely coherent, clear in direction, or fixed in outcome dramatically limits the usefulness of the life cycle model. In its place, I propose a unit of social analysis based in aspiration rather than event. I call this the vital conjuncture—integrating the "vital" of demographic vital events with Bourdieu's conception of the conjuncture of structure and action. Vital conjunctures suggest a new way of aggregating life history experiences and thus working between the individual and the social, free from the stultifying assumption of Stapes de vie. To illustrate the usefulness of the concept of "vital conjuncture, I focus on motherhood among young, educated Beti women in southern Cameroon. I demonstrate that rather than a clear threshold into female adulthood, here motherhood is a loosely bounded, fluid status. Contrary both to folk intuition and to the assumptions of a life cycle framework, Beti motherhood is not a stable status. Beti women who have borne children are not necessarily mothers, at least not all the time. Motherhood, instead, constitutes a temporary social status, an agent position that can be inhabited in specific forms of social action. The material offers perhaps an extreme example of what I argue is a more general phenomenon: "life stages" emerge only as the result of institutional projects, their coherence should be an object, rather than an assumption, of ethnographic inquiry. [Keywords: life course, Africa, demography, vital conjuncture]     

遗传负荷理论的一种普适框架

遗传负荷表示种群由于遗传变异能力的存在而在平均适宜度上的损失,定量讨论各种遗传负荷,对研究现实发生水平上的物种进化具有重要意义,以往的遗传负荷理论从种群平衡出发,探讨现实发生水平上的物种进化,可是,进化是种群平衡的位移;这便构成了理论与现实之间的矛盾,为拓展以往的遗传负荷理论,给出了一个描述各种遗传负荷的普适理论框架,利用这个理论框架既能探讨平衡种群的遗传负荷,又能模写非平衡种群的遗传负荷及其变化,从而克服了以往的遗传负荷理论不能描述非平衡种群和不时与生物进化现实相悖的不足之处,为研究物种的进化提供了一种可靠的模拟方法。     

Toward a cognitive ecology

The emergence of cognitive psychology as the dominant approach to understanding human behaviors and actions acknowledges the importance of internal mental operations in generating specific behavioral responses to sets of external stimuli. Traditional behaviorist interpretations that rely primarily on external inputs as the precursors of action have been largely replaced by cognitive approaches. The main intent of this article is to outline the major areas that require exploration if we wish to apply fully the principles and insight of cognitive science to behavioral ecology.