Relationships between specialized cells, capillaries and intermediary cytofibrillary elements. XVth note. Biological evolution of the respiratory stereotype and subsystem in aquatic vertebrates

The author continues in aquatic vertebrates the study of the evolution of the respiratory stereotype initiated in the XIIth note of this series and carried out in the light of the systemic conception (Bertalanffy), of Needham's theory of order in nature, and of the theory of biological stereotypes (Marza, Repciuc, Eskenasy). The stability of some characters of the respiratory stereotype inherited by vertebrates from invertebrates is pointed out. The respiratory stereotype in vertebrates gradually passed from the respiration of water-dissolved oxygen through branchiae and skin, to the concomitant uptake of this form and of air oxygen (through buccopharyngeal formations, gaseous bladder or rudimentary lungs in osseous fishes), the double respiration (in Amphibia) and later the air respiration in Reptilia. The five steps of this gradual evolution are described, as well as the conditions of the evolution from crossopterygians to Tetrapoda (amphibians and reptiles).     

Relationships between specialized cells, capillaries and intermediary cytofibrillary elements. XIIth note. Biological evolution of the respiratory stereotype and subsystem in invertebrates

This note presents the respiratory stereotype and subsystem in invertebrates, developing the previous notes on the emunctory stereotype and subsystem (Xth and XIth notes). As in the previous ones, Cannon's homeostasis conception and Bertlanffy's theory of systems were corroborated with Needham's theory of internal laws and of limits of organizational biological levels, and with the author's theory of biological stereotypes (Marza, Repciuc, Eskenasy, 1962). Four links of the respiratory stereotype (Rsp. Stp.) and subsystem (Rsp. SS) were distinguished. The respiratory subsystem was differentiated when, in triblastic animals, the organizational level of higher worms and of their offsprings was reached. The four links of the Rsp. Stp. are: the Ist link is represented by the oxidoreduction processes of tissue and organ cells; the IInd is the internal conveying link of O2 and CO2; the IIIrd comprises the osmotic surfaces changes and the transport of gases inwards the branchiae or lungs, and later by the water (respectively air)--blood barrier; the IVth link is formed from the structures and mechanisms of rhythmic movements which significantly increase the exchanges at the barrier level. Each link has its specific properties. The gradual evolution of each link and of the vicarious organs of gas exchange is dwelt upon, as well as the interactions between the respiratory subsystem and the other homeostasis subsystems. The theoretical interpretation of the Rsp. Stp. and Rsp. SS evolution also resorted to the theories of stabilizing selection (Schmalhausen, 1949), of canalizing selection (Waddington, 1975 and of disruptive selection (Simpson, 1953; Mayr, 1970).     

Evolution of amniote dentine apposition rates

In amniotes, daily rates of dentine formation in non-ever-growing teeth range from less than 1 to over 25 μm per day. The latter value has been suggested to represent the upper limit of odontoblast activity in non-ever-growing teeth, a hypothesis supported by the lack of scaling between dentine apposition rates and body mass in Dinosauria. To determine the correlates and potential controls of dentine apposition rate, we assembled a dataset of apposition rates, metabolic rates and body masses for ca 80 amniote taxa of diverse ecologies and diets. We used phylogenetic regression to test for scaling relationships and reconstruct ancestral states of daily dentine apposition across Amniota. We find no relationship between body mass and daily dentine apposition rate (DDAR) for non-ever-growing teeth in Amniota as a whole or within major clades. Metabolic rate, the number of tooth generations, diet and habitat also do not predict or correspond with DDARs. Similar DDARs are found in large terrestrial mammals, dinosaurs and marine reptiles, whereas primates, cetaceans and some smaller marine reptiles independently evolved exceptionally slow rates. Life-history factors may explain the evolution of dentine apposition rates, which evolved rapidly at the origin of major clades.     

Sketch for a Theory of Evolution Based on Coding

At the heart of evolutionary theory lays the notion of replication. Unfortunately, this notion is far less exact than the weight of its importance. In this paper, it is argued that replication always involves coding. Furthermore, when a theory of evolution is built on replication based on coding, a unifying and coherent picture arises that sheds new light on some of the controversies and open questions in contemporary biology, such as what are the roles of phylogeny and ontogeny in evolution, and how to characterize and explain the increase of biological complexity.     

The molecular origin and evolution of dim‐light vision in mammals

The nocturnal origin of mammals is a longstanding hypothesis that is considered instrumental for the evolution of endothermy, a potential key innovation in this successful clade. This hypothesis is primarily based on indirect anatomical inference from fossils. Here, we reconstruct the evolutionary history of rhodopsin—the vertebrate visual pigment mediating the first step in phototransduction at low‐light levels—via codon‐based model tests for selection, combined with gene resurrection methods that allow for the study of ancient proteins. Rhodopsin coding sequences were reconstructed for three key nodes: Amniota, Mammalia, and Theria. When expressed in vitro, all sequences generated stable visual pigments with λ_MAX values similar to the well‐studied bovine rhodopsin. Retinal release rates of mammalian and therian ancestral rhodopsins, measured via fluorescence spectroscopy, were significantly slower than those of the amniote ancestor, indicating altered molecular function possibly related to nocturnality. Positive selection along the therian branch suggests adaptive evolution in rhodopsin concurrent with therian ecological diversification events during the Mesozoic that allowed for an exploration of the environment at varying light levels.     

Is host‐specificity of weed biological control agents likely to evolve rapidly following establishment?

Over 352 herbivore species have now been intentionally introduced into new regions as weed biological control agents. Recent evidence shows that rapid and significant evolution in host-specificity can occur. The risk of non-target use by biological control agents increasing to unacceptable levels through rapid evolution therefore needs to be considered. In addition, weed biological control offers many as yet largely unexploited opportunities for improving our basic understanding of host-specificity and its evolution. We therefore evaluate the evidence that rapid evolution (1) alters the use of existing hosts, and (2) alters the fundamental host-range. Most cited examples of so-called host shifts from weed biological control were not the result of genetic change. There was only limited evidence of genetically altered performance on a non-target host and no evidence of altered fundamental host-range. We conclude, from both theory and the available data, that only altered use of existing hosts (through quantitative genetic changes) needs be considered when evaluating the risk of rapid evolution. Host-specificity testing methodologies can be improved and adapted to better assess the risk of occurrence of post-release evolution.     

Primary catalytic systems of biogenesis and structure-functional evolution of biocatalysers.

An important aspect of biological evolution is the development of biocatalyzers. The connection between abiotic and biological catalyzers is discussed, and the role of metal ions as primary catalysts is considered. The evolutionary demand for greater specificity and efficiency may have been fulfilled through the formation of metal-organic complexes and later through enzyme systems. Metal ions are probably responsible for the formation of some of the isoenzymes found in contemporary organisms.     

Patterns and Processes in Cultural Evolution

Darwinian models of cultural change have been motivated, in part, by the desire to provide a framework for the unification of the biological and the human sciences. In this paper, drawing upon a distinction between the evolution of enabling mechanisms for the acquisition and dissemination of knowledge (EEM) and the evolution of epistemic theses as cultural products (EET), we propose a model of how culture emerges as a product of biological evolution on the basis of the concept of reaction norms. The goal of this model is to provide a means for conceptualizing how the biological and the cultural realms are connected, when they start to disconnect, and what the key transitions are. We then assess the viability of a Darwinian approach to cultural change. We conclude that the prospects of producing a Darwinian model of cultural change that unifies the human sciences in a way that mirrors the unification of the biological sciences in the light of Darwin’s theory are rather dim.     

Darwin after 100 years. 1983.]

The triumph of Darwinism, together with the rise of Genetics, produced the virtual abandonment of the problem of form in Biology. The statement that any adaptive theory is tautological is however poor, the adaptation concept having an evident intuitive content. As in Geometrical Optics, a ray of light is, among the crowd of continuous curves uniting two points, the one requiring the minimum time for the light to go from one point to the other, so actual evolution, among the crowd of virtual evolutions between two forms, is the one best fitted to face 'selective pressure' in a given environment. The effect of selective pressure on the genome is unfortunately a merely theoretical not quantifiable concept. Most biological forms are forced by their internal stability to an essential fixity, so that the leap from one type-form to another should be abrupt-catastrophic. A good theory of evolution depends on a proper understanding of specific form stability. Biology must eventually return to the concept of ideal structure, the Goethian 'Urbild'.     

The origins of human ageing.

The origins of human ageing are to be found in the origins and evolution of senescence as a general feature in the life histories of higher animals. Ageing is an intriguing problem in evolutionary biology because a trait that limits the duration of life, including the fertile period, has a negative impact on Darwinian fitness. Current theory suggests that senescence occurs because the force of natural selection declines with age and because longevity is only acquired at some metabolic cost. In effect, organisms may trade late survival for enhanced reproductive investments in earlier life. The comparative study of ageing supports the general evolutionary theory and reveals that human senescence, while broadly similar to senescence in other mammalian species, has distinct features, such as menopause, that may derive from the interplay of biological and social evolution.     

A theoretical framework for defining some concepts in evolution.

We present a theoretical framework for biological evolution with the intention of giving precise mathematical definitions of some concepts in evolutionary biology such as fitness, evolutionary pressure, specialization and natural selection. In this framework, such concepts are identified with well-known mathematical terms within the theory of dynamical systems. We also discuss some more general implications in evolution; for instance, the fact that our model naturally exhibits a frequency spectrum of the type 1/f for low frequencies of evolutionary events.     

Theory of V.A. Dogiel on polymerization and oligomerization as a general integration concept

The theory of V.A. Dogiel on the significance of polymerization and oligomerization processes in the evolution of Protozoa and Metazoa is compared with the paper of I.I. Schmalhausen (1972) on factors and steps of aromorph evolution. Dogiel’s theory is considered as a general integration conception. Four steps are distinguished in the evolution of biological systems: (1) formation of morphofunctional system by units of the lower structural level, (2) polymerization of morphofunctional units of a system, (3) oligomerization of morphofunctional units of system by means of their reduction, uniting, or differentiation, (4) integration and stabilization of a system owing to development of morphofunctional connections between its parts.     

The fate of the blastocele and homology of early stages of vertebrate embryos

A disputable problem is discussed, which cavity in the Amniota embryo corresponds to blastocoele. General morphophysiological characteristics of the embryos at the blastula stage are presented. Basing on comparative survey of the data on origin, functions and fate of the blastocoele in development of vertebrate embryos, the notion is substantiated that the subembryonal cavity corresponds to blastocoele in Amniota. A critical analysis is given to another interpretation, according to which blastocoele in Amniota is a cleft between epi- and hypoblast. Ideas on homology criteria are explained, with a reference to initial stages of the embryonal development. Since prospective importance of blastocoele in low Chordata (convertion into gastrocoele) is different, a conclusion is made about incomplete homology of blastocoele in the animals mentioned. A hypothesis is put forward on pathways of changes of prospective importance of blastocoele in the vertebrate phylogenesis, in connection with their transition to meroblastic development. The problem on changes in assimilation of yolk by the vertebrate embryo at transition from holoblastic to meroblastic development is discussed from comparative point of view, as well as on nature of yolk entoderm in Amniota and Anamnia.     

A general model for the scaling of offspring size and adult size

Understanding evolutionary coordination among different life-history traits is a key challenge for ecology and evolution. Here we develop a general quantitative model predicting how offspring size should scale with adult size by combining a simple model for life-history evolution with a frequency-dependent survivorship model. The key innovation is that larger offspring are afforded three different advantages during ontogeny: higher survivorship per time, a shortened juvenile phase, and advantage during size-competitive growth. In this model, it turns out that size-asymmetric advantage during competition is the factor driving evolution toward larger offspring sizes. For simplified and limiting cases, the model is shown to produce the same predictions as the previously existing theory on which it is founded. The explicit treatment of different survival advantages has biologically important new effects, mainly through an interaction between total maternal investment in reproduction and the duration of competitive growth. This goes on to explain alternative allometries between log offspring size and log adult size, as observed in mammals (slope = 0.95) and plants (slope = 0.54). Further, it suggests how these differences relate quantitatively to specific biological processes during recruitment. In these ways, the model generalizes across previous theory and provides explanations for some differences between major taxa.     

Pollenmorphologie Von Borago Officinalis L.

The pollen morphology of the 16 recognized species of the genus Asphodelus L. (Asphodelaceae) has been investigated by light and scanning electron microscopy. Four pollen types can be distinguished on the basis of variation in size of the polar, equatorial longitudinal and transverse axes, as well as in exine structure and sculpturing, which correlate with the subdivision of the genus into sections. Correlations between pollen size and some biological characters are made. Phylogenetic implications are suggested, and trends of pollen evolution in the genus are indicated.     

Speculations on the evolution of ion transport mechanisms.

Primate cells evolved a plasma membrane to restrict the loss of important molecules. The osmotic problems that then arose were solved in one of several ways. Of major importance was the evolution of specific ion pumps, to actively extrude those salts whose inward diffusion would have led to swelling and lysis. In addition, these pumps allowed the cell to store energy in the form of ion gradients across the membrane. Thus, even in the earliest stages, the evolution of ion transport systems coincided with the development of mechanisms which catalyzes the energy transformations. It is postulated that an "ATP"-driven proton pump was one of the first ion transport systems. Such a proton pump would extrude hydrogen ions from the cell, establishing both a transmembrane pH gradient (alkaline inside) and a membrane potential (negative inside). This difference in electrochemical potential for protons (the proton-motive force) could then drive a variety of essential membrane functions, such as the active transport of ions and nutrients. A second major advance was the evolution of an ion transport system that converted light energy into a form which could be used by the cell. The modern model for this is the "purple membrane" of Halobacterium halobium, which catalyzes the extrusion of protons after the capture of light. The protonmotive force generated by such a light-driven proton pump could then power net synthesis of ATP by a reversal of the ATP-driven proton pump. A third important evolutionary step associated with ion transport was the development of a system to harness energy released by biological oxidations. Again, the solution of this problem was to conserve energy as a protonmotive force by coupling the activity of a respiratory chain to the extrusion of protons. Finally, with the development of animal cells a more careful regulation of internal and external pH was required. Thus, an ATP-driven Na+-K+ pump replaced the proton-translocating ATPase as the major ion pump found in plasma membranes.     

遗传伦理问题起源的研究与对策

遗传伦理问题是生命科学领域最具争议并最难以妥善解决的问题之一。近年来, 此类问题的研究主要是围绕遗传伦理问题的种类及解决方法进行的。但关于遗传伦理问题起源的系统研究尚不多见, 这也使相应对策的提出显得缺乏理论支撑。文章从人类生物进化与文化进化的双重角度深入探讨了遗传伦理问题发生的进化根源和演化规律。人类是生物进化与文化进化的双重产物, 是地球上唯一既具有生物属性又具有文化属性的物种。通过对人类生物进化与文化进化及其生物属性与文化属性特点的比较研究, 文章提出了任何伦理问题都可以从人类的生物进化与文化进化之间相互作用所产生的冲突中找到其发生根源的观点, 其目的是为研究遗传伦理问题及其对策的提出寻求理论和实践上的依据。同时, 提出了一系列关于遗传伦理问题的对应策略。文章的最终目的并非仅仅为某种观点能被接受, 而是希望通过对遗传伦理问题及其起源的了解和认识, 使遗传学领域的决策者和研究者更具使命感与责任感, 使一般公众对遗传学研究及其应用少一些误解, 多一些理性, 从而使遗传学事业能健康、持续发展, 造福人类。     

Quasi-elastic light scattering from migrating chemotactic bands of Escherichia coli.

We report the observation of migrating chemotactic bands of Escherichia coli in a buffer solution. The temporal development of the bacterial density profile is observed by the scattered light intensity as the band migrates through a stationary laser beam. We have made a preliminary analysis of the observed band profile with help of the Keller-Segel theory. The model accounts for only some aspects of the observed time evolution of the density profile. The microscopic motility characteristics of the E. coli in the band are simultaneously studied by photon correlation. The measured correlation functions are analyzed to obtain the spatial dependence of the half-width within the band. A simple analytical model is proposed to account for the contribution of the twiddle motion to the correlation function. By analyzing the correlation function as a superposition of straight-line and twiddle motions, we obtain a satisfactory agreement between the theory and the measured angular dependence of the line shape. As a consequence we are able to extract a parameter beta, which measures the average fraction of twiddling bacteria in the center of the band at a given time.     

On the “cytosociology” of enzyme action in vivo: A novel thermodynamic correlate of biological evolution

The evolution of enzyme action in vivo is examined, in the light of established thermodynamic correlates of biological evolution. Adopting a “process” view of matter in the “living state,” the authors focus the analysis on the transition-state theory of reaction rates. Thus, the free-energy change associated with the transition-state barrier is seen as a primary target in the evolution of cellular metabolism. The utility and limitations of reductionistic approaches to enzyme evolution, based on the single enzyme, are explored first. Then, canvassing the wealth of evidence on the role of enzyme organization in vivo, the authors synthesize a “cytosociological” view of enzyme evolution. In this view, a composite (resultant) of individual transition-state barriers is deemed a more appropriate “potential function” for modification in the higher evolution of cell metabolism. The suggested direction of evolutionary changes in this function, dictated by the increasing “socialization” of enzyme action in vivo, stands as a novel postulate. This approach is shown to be completely consonant with current thinking on the thermodynamics of biological evolution, and to provide further insight into the nature of material transformations in the “living state”.     

Misconceptions About Evolution in Brazilian Freshmen Students

Regarding such an important issue as our origin, as well as the origin of all biological diversity, it is surprising to realize that evolution still faces drawbacks in keeping its deserved notability as a unifying theory in biology. This does not happen because evolutionism lacks validity as a scientific theory, but rather because of several misconceptions regarding evolutionary biology that were and continue to be found in elementary and secondary education. Furthermore, mistaken evolutionary ideas also affect some philosophical and social issues. The aim of the present study was to evaluate knowledge about evolution among freshman students from distinct majoring areas at Universidade Estadual do Centro-Oeste do Paraná (UNICENTRO), Brazil. The research was carried out based on a ten-question questionnaire about evolution with distinct levels of difficulty, comprising the most observed misconceptions. In this study, 231 students attending classes in biological sciences (morning and evening schedule), exact sciences (agronomy, physics, chemistry, and math), and human sciences (history, geography, and pedagogy) were interviewed. The total average of right answers was 48.8%, and the highest average per course obtained was 58.7% from the students attending biological sciences (evening schedule). Although evolutionary biology and ecology are supposed to represent teaching guide issues according to the recommendations of the National Curricular Parameters for the Secondary School, the data obtained suggest that the evidence for evolution, the role of natural selection and random events, as well as the sources of variation, must be better focused at schools.