Hormonal correlates of individual quality in a long-lived bird: a test of the ‘corticosterone–fitness hypothesis’

Measuring individual quality in vertebrates is difficult. Focusing on allostasis mechanisms may be useful because they are functionally involved in the ability of an individual to survive and reproduce in its environment. Thus, a rise in stress hormones levels (corticosterone) occurs when an organism has to cope with challenging environmental conditions. This has recently led to the proposal of the ‘cort–fitness hypothesis’, which suggests that elevated baseline corticosterone levels should be found in individuals of poor quality that have difficulty coping with their environment. We tested this hypothesis by comparing an integrative measure of individual quality to baseline corticosterone in black-browed albatrosses (Thalassarche melanophrys). We found that individual baseline corticosterone levels were related to individual quality and highly repeatable from one breeding season to the next. Importantly, this relationship was found in males, but not in females. Therefore, we suggest that the relationship between quality and baseline corticosterone levels may depend on the environmental and energetic constraints that individuals have to cope with.     

Prospects for Studies of Morphological Variability of Land Pulmonate Snails

The main goal of modern investigations into the morphological variability of land pulmonate snails was defined as designing the patterns of taxa structure on the basis of historical analysis of their taxonomic studies. Transition from the investigation of individual characters to an analysis of the organism as a whole assumes the application of the system approach. Systemic properties of the organism can be revealed through the key characters reflecting the process of evolutionary transformation of the correlation chains. In the case of land pulmonate snails, the relationship between the operative and conservative subsystems of the organism can serve as such a key character. The operative subsystem-cephalopodium-fulfills the function of active contacts with the environment; the conservative subsystem-the shell and its content-exercises protective functions. The subsystems are in conflict, and its resolution establishes the main patterns of the organization of pulmonate snails.     

Living Precisely in Fin-de-Siècle Vienna

Vienna’s Institute of Experimental Biology, better known as the Vivarium, helped pioneer the quantification of experimental biology from 1903 to 1938. Among its noteable scientists were the director Hans Przibram and his brother Karl (a physicist), Paul Kammerer, Eugen Steinach, Paul Weiss, and Karl Frisch. The Vivarium’s scientists sought to derive laws describing the development of the individual organism and its relationship to the environment. Unlike other contemporary proponents of biological laws, however, these researchers created an explicitly anti-deterministic science. By “laws” they meant statistical regularities or “patterns.” They interpreted their experimental results in ways that forged a “third way” between determinism and pure spontaneity, aiming to capture the complexity of the interaction between the organism and its environment. This common feature of their research was made possible by the availability at the Vivarium of the latest in climate-control technology and of methods borrowed from statistical physics. The deeper roots of this search for a “third way” lay, I suggest, in the shared educational, social, and aesthetic experiences of the laboratory’s workers.     

Spider senses - technical perfection and biology

This essay deals with sensory biology in a broad sense. It takes mechanosensory systems of spiders to illustrate a few basic issues. Particular attention is given to two aspects. 1. There is a remarkable “ingenuity” in the uptake and transformation of the adequate stimuli way out in the sensory periphery, which is reflected by an intimate relationship between the physical properties of the stimuli and the characteristics of the structures receiving and transforming them. We need to understand the details of this relationship in order to understand the relationship of an organism to its environment. 2. Sensory systems represent interfaces between the environment and behavior. As highly selective filters they have not evolved to provide abstract knowledge but to guide a particular behavior. The signals sent to the central nervous system are meaningful only in regard to their behavioral significance. – Some details of stimulus transformation in biological strain gauges (slit sensilla), airflow detectors (trichobothria) and touch receptors (tactile hairs) are described. Some of the refinement in the periphery is then meshed with the behavior of the whole organism. In this way the value shall be underlined of trying to understand reductionist details as building blocks of the complexity which enables an organism to behave in its own particular way in its species specific environment.     

An organism-centered approach to some community and ecosystem concepts

We present a discussion of the ecological concept of the niche based on the perspective of the individual organism, rather than that of a population or species. This discussion is then expanded to include other related ecological concepts such as guild, environment, habitat and functional group.Using the individual as the focus permits the development of a system of concepts which, we believe, approximate the way that ecological interactions occur in nature.     

The evolution of multicellularity in animals as a shift in biological autonomy

The hypothesis is advanced that major evolutionary innovations are characterized by an increase of organismal autonomy in the sense of an emancipation from the environment. After a brief overview of the literature on this concept, increasing autonomy is defined as the evolutionary shift in the individual system-environment relationship, so that the direct influences of the environment are gradually reduced and a stabilization of self-referential, intrinsic functions within the system is generated. This is described as relative autonomy because numerous interconnections with the environment and dependencies upon it are retained. Elements of an increasing autonomy are spatial separations, an increase in homeostatic functions, internalizations and an increase in physiological and behavioral flexibility. These elements are described by taking the transition from single cells to metazoans as a case study. The principle of increasing autonomy is of central relevance for understanding this transition. The hypothesis does not contradict the principle of adaptation, but rather contributes to a further understanding of its elements as it supplies aspects for a reconsideration of the relationship between the outside and the inside, between organism and environment.     

Does DNA alone determine the development of the organism? (the information aspect of the problem)

Two closely related controversial problems are discussed: whether the developmental processes can be reduced to the synthesis of polypeptides encoded in DNA, and whether the information in DNA is equivalent to that in the adult organism. Critically considered are the ideas that DNA is only responsible for the protein synthesis, whereas morphogenesis proceeds independently and according to epigenetic regularities of its own. It is stated that development is the realization of genetic information in which more elementary (molecular) processes unambiguously determine a more complex cellular level which in its turn determines morphogenesis of tissues and organs. Various mechanisms of the appearance of new information in the course of development are considered. The statement is made that new information concerns only some individual characters of the organism, whereas most of information that determines the process of development and the structure of the adult organism is created in the course of evolution, is stored in DNA and inherited.     

A model for the age-dependent dynamics of growth of terrestrial mammals

Two hypothetical biological mechanisms were proposed that largely determine the dynamics of growth of overland mammals. The first mechanism is the maintenance of a spatial similarity of the anatomy of the organism during its growth, and the second is the maintenance of the stability of the internal environment of the organism. On the basis of the advanced hypothesis, a model of age-dependent dynamics of growth was constructed, and a differential equation describing the changes in the body mass with time was derived. According to this model, the dynamics of growth and the mass of an adult individual are determined by two energy constants that characterize the mechanism of food assimilation and the energy expenditures for the movement of the individual in space. The deviation between the solution obtained and the experimental data on age-dependent changes in the mass of the human body was on the average 6%. These insignificant deviations were explained in the framework of the proposed hypothesis, which indicates its validity.     

Rethinking individuality: the dialectics of the holobiont

Given immunity’s general role in the organism’s economy—both in terms of its internal environment as well as mediating its external relations—immune theory has expanded its traditional formulation of preserving individual autonomy to one that includes accounting for nutritional processes and symbiotic relationships that require immune tolerance. When such a full ecological alignment is adopted, the immune system becomes the mediator of both defensive and assimilative environmental intercourse, where a balance of immune rejection and tolerance governs the complex interactions of the organism’s ecological relationships. Accordingly, immunology, which historically had affiliated with the biology of individuals, now becomes a science concerned with the biology of communities. With this translocation, the ontological basis of the organism is undergoing a profound change. Indeed, the recent recognition of the ubiquity of symbiosis has challenged the traditional notions of biological individuality and requires a shift in the metaphysics undergirding biology, in which a philosophy of the organism must be characterized by ecological dialectics “all-the-way-down.”     

Specific features in realization of the principle of minimum energy dissipation during individual development

Realization of the principle of minimum energy dissipation (Prigogine??s theorem) during individual development has been analyzed. This analysis has suggested the following reformulation of this principle for living objects: when environmental conditions are constant, the living system evolves to a current steady state in such a way that the difference between entropy production and entropy flow (?? _u function) is positive and constantly decreases near the steady state, approaching zero. In turn, the current steady state tends to a final steady state in such a way that the difference between the specific entropy productions in an organism and its environment tends to be minimal. In general, individual development completely agrees with the law of entropy increase (second law of thermodynamics).     

Genotype networks in metabolic reaction spaces

Background  

A metabolic genotype comprises all chemical reactions an organism can catalyze via enzymes encoded in its genome. A genotype is viable in a given environment if it is capable of producing all biomass components the organism needs to survive and reproduce. Previous work has focused on the properties of individual genotypes while little is known about how genome-scale metabolic networks with a given function can vary in their reaction content.     

Coevolution of physiological systems

Coevolution is the interaction in the process of evolution of different species that are closely related biologically but do not exchange genetic information. In this paper, we address the problem of coevolution of the whole organism’s physiological systems as a process of the interrelated development of structure and function as well as their regulatory systems during the formation of living organisms. We consider the coevolution of osmoregulation and the nitrogen metabolism type, systemic and individual coevolutionary strategies of cell volume regulation in poikiloosmotic and homoiosmotic animals, coevolution of effectory organs and endocrine factors in the development of water–salt homeostasis, co-involvement of neurohypophyseal nonapeptides and glucagon-like peptide-1 in the regulation of the renal function aimed at stabilizing physico-chemical parameters of extracellular fluids which make up the internal environment of the organism.     

Questions and Answers about C. P. S

A wider concept of disease is developing, which deals with the social environment, not only with the physical, chemical or ecological factors, as they affect the homeostasis of the internal environment of the organism. In such a concept it is the fitness of the whole personality which determines ease or dis-ease in adaptation. If the medical profession is to retain the strategic direction as well as the tactical command of the battle for health, it must widen the bases of its educational program so that every physician will understand and conform to the plan of battle even though his individual role is highly restricted; so that even in the office of a technical specialist the whole personality of the patient in relation to his whole environment is dealt with.     

THE MEANING OF DISEASE

A wider concept of disease is developing, which deals with the social environment, not only with the physical, chemical or ecological factors, as they affect the homeostasis of the internal environment of the organism. In such a concept it is the fitness of the whole personality which determines ease or dis-ease in adaptation. If the medical profession is to retain the strategic direction as well as the tactical command of the battle for health, it must widen the bases of its educational program so that every physician will understand and conform to the plan of battle even though his individual role is highly restricted; so that even in the office of a technical specialist the whole personality of the patient in relation to his whole environment is dealt with.     

Symbiosis as a source of selectable epigenetic variation: taking the heat for the big guy

Evolutionary developmental biology is based on the principle that evolution arises from hereditable changes in development. Most of this new work has centred on changes in the regulatory components of the genome. However, recent studies (many of them documented in this volume) have shown that development also includes interactions between the organism and its environment. One area of interest concerns the importance of symbionts for the production of the normal range of phenotypes. Many, if not most, organisms have ‘outsourced’ some of their developmental signals to a set of symbionts that are expected to be acquired during development. Such intimate interactions between species are referred to as codevelopment, the production of a new individual through the coordinated interactions of several genotypically different species. Within the past 2 years, several research programmes have demonstrated that such codevelopmental schemes can be selected. We will focus on symbioses in coral reef cnidarians symbiosis, pea aphids and cactuses, wherein the symbiotic system provides thermotolerance for the composite organism.     

A Simple Study in Ecological Energetics using a Gall-fly and its Insect Parasites

The field ant, Lasius flavus provides an answer to the problem of demonstrating, in schools, the effect of an organism on its surroundings. There is a simple pattern of plant distribution on the anthills which is different from the surrounding meadow and the differences between anthill and undisturbed soil can be demonstrated by simple experiments. These differences modified the environment of the ant colonies in ways which were favourable to their development. The anthill is a product of social organisation which is in some ways comparable to the attempts of human societies to control their environment.     

Stasis: a coevolutionary model

Traditional neo-Darwinian explanations for stasis involve limited variation, developmental constraints and stabilizing selection. Of these, stabilizing selection is regarded as the mechanism operating most widely. Arguments based on stabilizing selection, however, implicitly assume a one-way evolutionary relationship between organism and environment. In this paper, I suggest that stasis may arise in a number of different ways as a result of organism/environment coevolution. The chief causes of stasis may be the attainment of coadapted equilibria between organism and environment and periods of quiescence within and between arms races. I also suggest that many cases of stasis in the fossil records may be apparent rather than real due to a reliance on gross morphological trends and that apparently large environmental changes during which stasis persists may not reflect change in the coadapted components of the organisms' environment.     

Evolutionarily stable learning schedules and cumulative culture in discrete generation models

Individual learning (e.g., trial-and-error) and social learning (e.g., imitation) are alternative ways of acquiring and expressing the appropriate phenotype in an environment. The optimal choice between using individual learning and/or social learning may be dictated by the life-stage or age of an organism. Of special interest is a learning schedule in which social learning precedes individual learning, because such a schedule is apparently a necessary condition for cumulative culture. Assuming two obligatory learning stages per discrete generation, we obtain the evolutionarily stable learning schedules for the three situations where the environment is constant, fluctuates between generations, or fluctuates within generations. During each learning stage, we assume that an organism may target the optimal phenotype in the current environment by individual learning, and/or the mature phenotype of the previous generation by oblique social learning. In the absence of exogenous costs to learning, the evolutionarily stable learning schedules are predicted to be either pure social learning followed by pure individual learning (“bang-bang” control) or pure individual learning at both stages (“flat” control). Moreover, we find for each situation that the evolutionarily stable learning schedule is also the one that optimizes the learned phenotype at equilibrium.