Growth models in fossil arborescent cheilostome bryozoans

Paleobiology ◽  
1981 ◽  
Vol 7 (1) ◽  
pp. 68-86 ◽  
Author(s):  
Alan H. Cheetham ◽  
Lee-Ann C. Hayek ◽  
Erik Thomsen

Cheilostome bryozoans that grew as rigidly erect arborescent colonies dominate many bryozoan-rich assemblages of Tertiary age, in which they are found most commonly as small dissociated fragments. The regularity with which branching and branch thickening occur in intact colonies of living species provides a basis for quantitative reconstruction of these growth processes in fossils. We propose models to describe branch thickening, develop methods to extend both thickening and branching models to fossils, investigate the thickening and branching properties of four Paleocene and five Oligocene species and compare the properties of these fossils to those of nine living species.The properties investigated are largely mutually independent and species specific irrespective of geologic age and have similar numerical ranges among different assemblages of coeval species. Species are evenly distributed across the range of possible morphologies between observed extremes, without obvious gaps. Statistically significant trends through time are identified in gradients of branch thickening, which have implications for the resistance of colonies to mechanical stress, and in angles of bifurcation, that are important in the way growing colonies occupy space.

Author(s):  
Martin Surbeck ◽  
Gottfried Hohmann

The nature of the relationships between males is a characteristic trait of many multi-male group living species with implications for the individuals. In our study population of bonobos, certain male dyads exhibit clear preferences for ranging in the same party and sitting in proximity. These preferences are not reflected in the frequency of aggression towards each other and only to some extent in their affiliative and socio-sexual behaviours. While bonobo males at LuiKotale clearly do not benefit from close relationships in the way chimpanzee males do (cooperative hunting, territorial patrol, mate competition), some relationships might result from close associations between their mothers. In some particular situations, these male relationships can be very important as in the case of an orphan adopted by his older maternal brother. La nature des relations entre mâles est un trait caractéristique de plusieurs groupes qui ont plusieurs mâles, avec des implications au niveau d’individus. Dans notre étude des populations de bonobos, certains dyades mâles montrent une préférence à aller dans le même groupe et s’asseoir proche l’un de l’autre. Cette préférence n’est pas reflétée dans la fréquence d’agression entre eux et est seulement lié, à degrés, à leur comportements socio-sexuels et d’appartenance. Tandis que les mâles bonobos à LuiKotale ne profitent pas de leur fortes relations comme les chimpanzés mâles (chasse coopérative, patrouille territoriale, compétition pour compagnon), ils peuvent aider leur partenaires à supporter le stress de la vie en groupe et peuvent en conséquence contribuer au bien-être des individus. Quelques proches associations entre les mâles peuvent provenir d’associations entre leurs mères. Dans quelques situations particulières, ces relations mâles prouvent leur importance comme dans le cas d’un orphelin adopté par son grand frère maternel.


Author(s):  
Eleonora Bilotta ◽  
Pietro Pantano

Structural models and patterns are vitally important for human beings. From birth, we base our emotional and cognitive representations of the external world on species-specific signals (the human face) and exploit these signals to structure our instinctive behavior. The creation of cognitive patterns to represent the world lies at the very heart of human cognition. It is this process that underlies our efficient use of signs, our ability to communicate with natural languages and to build cognitive artifacts, the way we organize the external world, and the way we organize external events in our memories and our flow of consciousness. Patterns are sometimes called schemas, or models, and discussed in terms of a gestalt (Piaget, 1960; 1970; Koelher, 1974). In the middle ages a pattern meant “the.original.proposed.to.imitation;.the. archetype;.that.which.is.to.be.copied;.an.exemplar” (from the On Line Etymology Dictionary). Modern use dates back to the XVIII century. In 1977 Christopher Alexander introduced a new way of using the term in architecture. For Alexander, a pattern was a model used to encode and organize existing knowledge, avoiding the need to reinvent the knowledge every time it was needed. For Alexander a pattern was “a three part rule, which expresses a relation between a certain context, a problem, and a solution” (Alexander et al., 1977).


2014 ◽  
Vol 70 (a1) ◽  
pp. C97-C97
Author(s):  
Keisuke Nagao ◽  
Kazue Nishimoto ◽  
Tomoaki Inuduka ◽  
Keiichi Edagawa

Quasicrystals possess quasiperiodicity, where the structure cannot be described simply by the repetition of unit cell like conventional crystals. This fact raises the question of how quasicrystals grow, i.e., what physical mechanism makes the growth of quasicrystals possible. While crystals can grow by copying a unit cell via local atomic interactions, nonlocal structural information seems to be required in the growth of quasicrystals. This problem has attracted much attention ever since the first discovery of a quasicrystal in 1984, and several theoretical growth models [1] have been proposed. However, no experimental studies have so far been reported, and it is still unclear whether these theoretical growth models apply to real quasicrystals. In the present study, we have conducted in-situ high-temperature electron microscopic (HRTEM: High-Resolution Transmission Electron Microscopy) observations of the growth process of decagonal quasicrystals to elucidate the growth mechanism. The growth processes of a decagonal quasicrystal of Al70.8Ni19.7Co9.5were observed by HRTEM in the temperature range 1073-1173K. Tiling patterns with edge length of about 2nm were constructed from a series of HRTEM images. They were analysed in the framework of the projection method. Here, we followed the procedures in our previous work [2]. We have already reported the results of some observations and analyses elsewhere [3]. However, the growth processes of them were on a small scale, and the results were indefinite. Recently, we have succeeded in observing a growth process on a massive scale. In this paper, we present the results of this observation and subsequent analyses, and discuss the growth mechanism of the quasicrystal.


2003 ◽  
Vol 33 (3) ◽  
pp. 480-489 ◽  
Author(s):  
Boris Zeide

So far, process-based models use largely the bottom-up approach. They start by describing physiological processes in a single plant element and then integrate the constituent processes to predict growth and dimensions of the tree and stand. Although bottom-up process models are praised for their contribution to knowledge of growth processes, their predictions are poor. The complementary top-down approach begins where the bottom-up model ends: with measurable variables such as height or diameter. This approach intends to uncover the ecophysiological processes responsible for the observed tree dimensions rather than to provide growth information for forest management. As foresters, we would like to utilize measurable variables to uncover inner mechanisms of growth in hope of predicting future diameter, number of trees, volume, and other practical variables. This means that we need to combine the top-down and bottom-up approaches. Examples of the united U-approach (so called because of its descending and ascending branches) are described. They demonstrate that growth models can be both meaningful and accurate.


Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 429
Author(s):  
Jaime Briseño-Reyes ◽  
José Javier Corral-Rivas ◽  
Raúl Solis-Moreno ◽  
Jaime Roberto Padilla-Martínez ◽  
Daniel José Vega-Nieva ◽  
...  

Lack of knowledge of individual tree growth in species-rich, mixed forest ecosystems impedes their sustainable management. In this study, species-specific models for predicting individual diameter at breast height (dbh) and total tree height (h) growth were developed for 30 tree species growing in mixed and uneven-aged forest stands in Durango, Mexico. Growth models were also developed for all pine, all oaks, and all other species of the genus Arbutus (strawberry trees). A database of 55,158 trees with remeasurements of dbh and h of a 5-year growth period was used to develop the models. The data were collected from 217 stem-mapped plots located in the Sierra Madre Occidental (Mexico). Weighted regression was used to remove heteroscedasticity from the species-specific dbh and h growth models using a power function of the tree size independent variables. The final models developed in the present study to predict dbh and total tree height growth included size variables, site factors, and competition variables in their formulation. The developed models fitted the data well and explained between 98 and 99% and of the observed variation of dbh, and between 77 and 98% of the observed variation of total tree height for the studied species and groups of species. The developed models can be used for estimating the individual dbh and h growth for the analyzed species and can be integrated in decision support tools for management planning in these mixed forest ecosystems.


2018 ◽  
Vol 27 (3) ◽  
pp. 103-134
Author(s):  
Renata Sammer

Resumo: O propósito deste artigo é investigar a filosofia da forma na escrita rosiana a partir das referências ao mundo natural encontradas no Grande sertão: veredas. Desse modo, busca-se não apenas iluminar a característica invenção rosiana, mas também descortinar uma metafísica, ou melhor, uma compreensão da metafísica que, em parte, afina-se com a contemporânea “virada ontológica”, que hoje instiga os estudos antropológicos, filosóficos e literários. Como identificado na ficção rosiana, a formulação de metafísicas distintas visa desconstruir a tradicional metafísica da representação de modo mais eficaz do que a crítica “pós-moderna” a ela dirigida. De fato, a variedade das espécies viventes que marca a escrita de Rosa termina por aproximar comparativamente metafísicas, perspectivas que se reúnem ao redor de um núcleo poético comum, “vital e irrepresentável” (ROWLAND, 2011, p. 18). Logo, este artigo privilegia a vida das plantas a fim de ressaltar a forma movente ou, ainda, o informe, que Rosa cultiva como ser da ficção. Como hipótese de trabalho, notamos que a variedade das formas das flores é aproximada do amor, assim compondo uma morfologia, e que a vingança, que conduz à guerra que entrecorta o mato, é o modo como essa cultura das formas moventes constrói sentidos e dá origem a novas formas. Como conclusão, veremos que a metafísica das plantas, tal como trabalhada no Grande sertão, ilumina a proposta filosófica de Rosa e coloca sua obra sob uma nova luz.Palavras-chave: metafísica da mistura; poesia; ontologia; Guimarães Rosa; filosofia da natureza.Abstract: The purpose of the present article is to investigate the philosophy of form in Rosian writing contained in the references to the natural world found in Grande Sertão: Veredas. Thus, we seek not only to illuminate the characteristic Rosian invention, but also to unveil a metaphysics, or rather an understanding of metaphysics which, in part, is tuned to the contemporary “ontological turn,” that presently instigates anthropological, philosophical, and literary studies. As identified in Rosian fiction, the formulation of different metaphysics aims to deconstruct the traditional metaphysics of representation in a more effective way than the “postmodern” critique addressed to it. In fact, the variety of living species that characterizes Rosa’s writings ends up comparatively approaching different metaphysics, perspectives that gather around a common, “vital and unrepresentable” (ROWLAND, 2011, p. 18) core. Thus, the emphasis given to the life of plants in this article seeks to emphasize the moving form or, likewise, what is formless, that Rosa cultivates as the nature of fiction. As a working hypothesis, we note that the variety in the form of flowers is approximated to love, thus composing a morphology, and that revenge, which drives the war that cuts through the bushes, is the way in which this culture of moving forms shapes new meanings and originates new forms. As a conclusion, we will see that the metaphysics of plants, as suggested in Grande Sertão, illuminates Rosa’s philosophical proposal and places his work under a new light.Keywords: metaphysics of mixture; poetry; ontology; Guimarães Rosa; philosophy of nature.


2018 ◽  
pp. 27-40
Author(s):  
Erika Lorraine Milam

This chapter considers the retrospective literature on Charles Darwin's work. These views on Darwin's intellectual development and legacy, such as that posited by Loren Eiseley, began the way many classes on the history of modern biology still begin: by emphasizing early-modern scientific empiricism and the desire of Enlightenment natural historians to catalog and classify all living species according to a great scale of nature. Against this background, Eiseley posited, evolutionary thinking—the idea that species have not been static in time, but some have gone extinct and others slowly evolved into new forms—emerged in France, rising from the secularized ashes of the revolutionary republic. Eiseley made clear that Darwin's legacy therefore rested on his innovative mechanism explaining the transformation of species. Like Eiseley, the retrospective essays and books published in the years after pointed to Darwin's theory of natural selection as his “most important generalization.”


Genetic relations among living species can be deduced from biochemical as well as morphological similarities, but our understanding of fossil species has depended entirely on their morphology. Residual proteins in fossils might provide genetic information, but their small quantity and chemical alterations due to time and environmental agents have prevented the obtaining of species-specific analysis. This report describes a radioimmunoassay capable of detecting extremely small amounts of fossil proteins, such as collagen and albumin. Species-specific proteins have been identified in a frozen Siberian mammoth, a Pleistocene bison, and a series of hum an fossils that includes Neanderthal, Homo erectus and Australopithecus robustus . This technique promises to provide molecular data on the genetic affinities of fossil and living species.


2016 ◽  
Vol 67 (10) ◽  
pp. 1546 ◽  
Author(s):  
Cassandra L. Rigby ◽  
Ross K. Daley ◽  
Colin A. Simpfendorfer

Deep-water sharks have low biological productivity and are vulnerable to exploitation with species-specific regional life history required to enable effective management. The present study describes the life history of two squalids collected from Australia: (1) the piked spurdog (Squalus megalops) from the tropical Great Barrier Reef; and (2) the Philippine spurdog (S. montalbani) from New South Wales. Maximum observed ages for males and females were 18 and 25 years for S. megalops and 28 and 27 years for S. montalbani. Multiple growth models were all well supported and indicated very slow growth rates for both species. The tropical S. megalops population was smaller and older at maturity than previously reported temperate populations. Males were mature at 352-mm stretched total length (LST) and 12.6 years, whereas females were mature at 422mm LST and 19.1 years. Squalus montalbani males were mature at 700mm LST and 21.8 years, whereas females were mature at 800mm LST and 26 years. Fecundity was lower for S. megalops than S. montalbani with two to three compared with nine to 16 embryos. Both species have a conservative life history, although in the event of overfishing the longer-lived, later-maturing and deeper-dwelling S. montalbani is likely to take longer to recover than S. megalops.


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