The hyoid arch and braincase anatomy of Acanthodes support chondrichthyan affinity of ‘acanthodians’

Solving the evolutionary relationships of the acanthodians is one of the key problems in reconstructing ancestral anatomical conditions for the jawed vertebrates (gnathostomes). Current debate concerns whether acanthodians are an assemblage of stem chondrichthyans, or a more generalized grade encompassing some early stem osteichthyans. The skull anatomy of Acanthodes bronni has been pivotal in these debates, owing to tension between chondrichthyan- and osteichthyan-like models of reconstruction. We use computed tomography scanning and traditional palaeontological techniques to resolve the long-standing debate about the anatomy of the jaw suspension. We establish the correct length of the hyomandibula and show that it attaches to a process on the ventrolateral angle of the braincase below the jugular vein groove. This condition corresponds precisely to that in chondrichthyans. This character represents an unambiguously optimized synapomorphy with chondrichthyans given current gnathostome phylogenies, corroborating the growing consensus of the chondrichthyan affinity of acanthodians.     

Leaf anatomy and water loss of in vitro PEG-treated ‘Valiant’ grape

Polyethylene glycol was used to induce water stress of micropropagated Valiant grape. Reduced growth and slow rooting were observed in treated plantlets with 2, 4 and 6% polyethylene glycol as compared to control plantlets with no polyethylene glycol in the rooting medium. At high concentrations of 4 and 6%, leaves exhibited wilting and necrosis. At the 2% level, plantlets recovered and grew satisfactorily. Detached leaves of treated plantlets with 2% polyethylene glycol lost less water than controls when exposed to low humidity for 4 hours. Leaf anatomy of plantlets treated with 2% polyethylene glycol, control (in vitro plantlets) and greenhouse-grown plants were compared under light microscopy. Leaves from control plantlets contained larger mesophyll cells, lacked normal palisade layer formation, had greater intercellular pore spaces and fewer chloroplasts. Leaves from polyethylene glycol-treated plantlets, however, had smaller mesophyll cells, a more defined palisade layer, reduced intercellular pore space and the greatest number of chloroplasts. These results suggest that an osmoticum such as polyethylene glycol may be used to induce more normal leaf anatomy and reduced water loss in micropropagated Valiant grapes.Abbreviations BA 6-benzylaminopurine - FAA formalin-acetol-alcohol - MS Murashige & Skoog (1962) medium - MW molecular weight - NAA napthaleneacetic acid - PEG polyethylene glycol - TBA tertiary butyl alcohol     

The imagination of ‘society’ in measurements of immigrant integration

Abstract

My aim in this contribution is to clarify in which way social scientific measurements of immigrant integration operate as a form of ‘social imagination’, that is, of the routinized and professionalized visualization of social life. Through such measurements, images of ‘society’ are produced that feed into larger social imaginaries. My discussion takes as an example Dutch discourse and research on integration. Crucial to the constitution of society in the Netherlands and many other Western European countries is what I call a culturist discourse that has many similarities to racism. This discourse demarcates the boundaries of society by rendering objectively observable the non-integrated who are considered to reside ‘outside society’. The image of society thereby produced is that of a morally cleansed realm: social problems are relegated to the domain ‘outside society’, consisting of persons in need of integration.     

The Fate of the Method of ‘Paradigms’ in Paleobiology

An earlier article described the mid-twentieth century origins of the method of “paradigms” in paleobiology, as a way of making testable hypotheses about the functional morphology of extinct organisms. The present article describes the use of “paradigms” through the 1970s and, briefly, to the end of the century. After I had proposed the paradigm method to help interpret the ecological history of brachiopods, my students developed it in relation to that and other invertebrate phyla, notably in Euan Clarkson’s analysis of vision in trilobites. David Raup’s computer-aided “theoretical morphology” was then combined with my functional or adaptive emphasis, in Adolf Seilacher’s tripartite “constructional morphology.” Stephen Jay Gould, who had strongly endorsed the method, later switched to criticizing the “adaptationist program” he claimed it embodied. Although the explicit use of paradigms in paleobiology had declined by the end of the century, the method was tacitly subsumed into functional morphology as “biomechanics.”     

The history of comparative anatomy in Jena — an overview

Summary Comparative anatomy and zoology both have long academic traditions in Jena. At first, the two subjects developed in parallel and had many similarites in research topics. This development is covered in the first part of the paper. The close relationship between the two subjects started to break apart when Carl Gegenbaur and Ernst Haeckel were active at Jena University. In 1865 Haeckel became the first full professor of zoology in Jena, and zoology became more independent from comparative anatomy. In the second part of our paper, we follow the developments in comparative anatomy in Jena from Gegenbaur’s immediate students up until the end of Hans B?ker’s tenure in Jena in the mid-1930s. Certain subjects are in focus throughout this period, for example vertebrate head morphology and development, (the “head problem”), the relationship between anatomy and biology, and evolutionary questions. Some of these subjects have remained important research topics in zoology and comparative anatomy in Jena until the present day.     

The fate of ‘biodegradable’ plastics in municipal leaf compost

Summary Blends of starch with polypropylene, starch with polyethylene, polycaprolactone with polyethylene, and a copolymer of -hydroxybutyrate and -hydroxyvalerate (PHB/V) were exposed to degrading leaves in a municipal leaf composting operation. Every month for 6 months, duplicate samples were analyzed for changes in weight and tensile properties, and many of these samples were further analyzed for changes in molecular weight and surface morphology. All results were compared to controls which were incubated for 6 months in moist, sterile leaves at a leaf compost temperature. Very little change was noted for any of the polyolefin blends over the 6-month period. In contrast, PHB/V samples showed massive deterioration with substantial weight loss. Although there was a decrease in molecular weight and a loss of tensile properties in leaf-exposed PHB/V films, the sterile control films also showed similar changes, but without weight loss. Of the microbial isolates from film surfaces, only fungi possessed PHB/V depolymerase activity.     

The spectre of ‘spurious’ correlations

Summary Ecologists often standardize data through the use of ratios and indices. Such measures are employed generally to remove a size effect induced by some relatively uniteresting variable. The implications of using the resultant data in correlation and regression analyses are poorly recognized. We show that ratios and indices often provide surprising and spurious results due to their unusual properties. As a solution, we advocate the use of randomization tests to evaluate hypotheses confounded by spurious correlations. In addition, we emphasize that identifying the appropriate null correlation is of utmost importance when statistically evaluating ratios, although this issue is frequently ignored.     

The fine structure of ‘homology’

There is long-standing conflict between genealogical and developmental accounts of homology. This paper provides a general framework that shows that these accounts are compatible and clarifies precisely how they are related. According to this framework, understanding homology requires both (a) an abstract genealogical account that unifies the application of the term to all types of characters used in phylogenetic systematics and (b) locally enriched accounts that apply only to specific types of characters. The genealogical account serves this unifying role by relying on abstract notions of ‘descent’ and ‘character’. As a result, it takes for granted the existence of such characters. This requires theoretical justification that is provided by enriched accounts, which incorporate the details by which characters are inherited. These enriched accounts apply to limited domains (e.g. genes and proteins, or body parts), providing the needed theoretical justification for recognizing characters within that domain. Though connected to the genealogical account of homology in this way, enriched accounts include phenomena (e.g. serial homology, paralogy, and xenology) that fall outside the scope of the genealogical account. They therefore overlap, but are not nested within, the genealogical account. Developmental accounts of homology are to be understood as enriched accounts of body part homology. Once they are seen in this light, the conflict with the genealogical account vanishes. It is only by understanding the fine conceptual structure undergirding the many uses of the term ‘homology’ that we can understand how these uses hang together.     

The ‘curse’ of Westermarck 1

This article consists of a critical application of recent theory of nationalism to the unusual case of Mauritius. It is a poly‐ethnic and poly‐religious society whose inhabitants neither share a mythical distant past nor consider themselves culturally identical, but where nation‐building has nevertheless been moderately successful since the late 1960s. Through an examination of the processes of institutional and cultural nation‐building in the island, it is argued that the current Eurocentric view of the nation (notably as a culturally homogeneous imagined community) must be modified to fit cases like this one. Thus, the value of nationalism and nationhood as comparative concepts is questioned.