bluuebunny/crossref_metadata_2025_split huggingface dataset:
An ecosystem‐level perspective of allelopathy
Authors: WARDLE DAVID A. , NILSSON MARIE‐CHARLOTTE , GALLET CHRISTIANE , ZACKRISSON OLLE 
Published: August 2010

ABSTRACTAllelopathy is an interference mechanism by which plants release chemicals which affect other plants; while it has often been proposed as a mechanism for influencing plant populations and communities, its acceptance by plant ecologists has been limited because of methodological problems as well as difficulties of relating the results of bioassays used for testing allelopathy to vegetation patterns in the field. Here we argue that the concept of allelopathy is more appropriately applied at the ecosystem‐level, rather than the traditional population/community level of resolution. Firstly, we consider the wide ranging effects of secondary metabolites (widely regarded as allelochemicals) on organisms and processes which regulate ecosystem function, including herbivory, decomposition and nutrient mineralization. It is apparent that plants with allelopathic potential against other organisms induce net changes in ecosystem properties, which may in turn impact upon the plant community in the longer term. We then illustrate these concepts using two contrasting examples of how invasive plant species with allelopathic potential may alter ecosystem properties through the production of secondary metabolites, i.e.Carduus nutans(nodding thistle) in New Zealand pastures andEmpetrum hermaphroditum(crowberry) in Swedish boreal forests. In both cases the production of secondary metabolites by the invasive species induces important effects on other organisms and key processes, which help determine how the ecosystem functions and ultimately the structure of the plant community. These examples help demonstrate that the concept of allelopathy is most effectively applied at the ecosystem‐level of resolution, rather than at the population‐level (i.e. plant‐plant interference).
Flight adaptations in Palaeozoic Palaeoptera (Insecta)
Authors: WOOTTON ROBIN J. , KUKALOVÁ‐PECK JARMILA 
Published: August 2010

ABSTRACTThe use of available morphological characters in the interpretation of the flight of insects known only as fossils is reviewed, and the principles are then applied to elucidating the flight performance and techniques of Palaeozoic palaeopterous insects. Wing‐loadings and pterothorax mass total mass ratios are estimated and aspect ratios and shape‐descriptors are derived for a selection of species, and the functional significance of wing characters discussed. Carboniferous and Permian ephemeropteroids (‘mayflies’) show major differences from modern forms in morphology and presumed flight ability, whereas Palaeozoic odonatoids (‘dragonflies’) show early adaptation to aerial predation on a wide size‐range of prey, closely paralleling modern dragonflies and damselflies in shape and wing design but lacking some performance‐related structural refinements. The extensive adaptive radiation in form and flight technique in the haustellate orders Palaeodictyoptera, Megasecoptera, Diaphanopterodea and Permothemistida is examined and discussed in the context of Palaeozoic ecology.
Building large trees by combining phylogenetic information: a complete phylogeny of the extant Carnivora (Mammalia)
Authors: BININDA‐EMONDS OLAF R. P. , GITTLEMAN JOHN L. , PURVIS ANDY 
Published: August 2010

ABSTRACTOne way to build larger, more comprehensive phylogenies is to combine the vast amount of phylogenetic information already available. We review the two main strategies for accomplishing this (combining raw dataversuscombining trees), but employ a relatively new variant of the latter: supertree construction. The utility of one supertree technique, matrix representation using parsimony analysis (MRP), is demonstrated by deriving a complete phylogeny for all 271 extant species of the Garnivora from 177 literature sources. Beyond providing a ‘consensus’ estimate of carnivore phylogeny, the tree also indicates taxa for which the relationships remain controversial (e.g. the red panda; within canids, felids, and hyaenids) or have not been studied in any great detail (e.g. herpestids, viverrids, and intrageneric relationships in the procyonids). Times of divergence throughout the tree were also estimated from 74 literature sources based on both fossil and molecular data. We use the phylogeny to show that some lineages within the Mustelinae and Canidae contain significantly more species than expected for their age, illustrating the tree's utility for studies of macroevolution. It will also provide a useful foundation for comparative and conservational studies involving the carnivores.
Trophic‐dynamic considerations in relating species diversity to ecosystem resilience
Authors: JOHNSON KRIS H. 
Published: August 2010

ABSTRACTComplexity in the networks of interactions among and between the living and abiotic components forming ecosystems confounds the ability of ecologists to predict the economic consequences of perturbations such as species deletions in nature. Such uncertainty hampers prudent decision making about where and when to invest most intensively in species conservation programmes. Demystifying ecosystem responses to biodiversity alterations may be best achieved through the study of the interactions allowing biotic communities to compensate internally for population changes in terms of contributing to ecosystem function, or their intrinsic functional redundancy. Because individual organisms are the biologically discrete working components of ecosystems and because environmental changes are perceived at the scale of the individual, a mechanistic understanding of functional redundancy will hinge upon understanding how individuals’ behaviours influence population dynamics in the complex community setting. Here, I use analytical and graphical modelling to construct a conceptual framework for predicting the conditions under which varying degrees of interspecific functional redundancy can be found in dynamic ecosystems. The framework is founded on principles related to food web successional theory, which provides some evolutionary insights for mechanistically linking functional roles of discrete, interacting organisms with the dynamics of ecosystems because energy is the currency both for ecological fitness and for food web commerce. Net productivity is considered the most contextually relevant ecosystem process variable because of its socioeconomic significance and because it ultimately subsumes all biological processes and interactions. Redundancy relative to productivity is suggested to manifest most directly as compensatory niche shifts among adaptive foragers in exploitation ecosystems, facilitating coexistence and enhancing ecosystem recovery after disturbances which alter species’ relative abundances, such as extinctions. The framework further explicates how resource scarcity and environmental stochasticity may constitute ‘ecosystem legacies’ influencing the emergence of redundancy by shaping the background conditions for foraging behaviour evolution and, consequently, the prevalence of compensatory interactions. Because it generates experimentally testable predictions for a priori hypothesis testing about when and where varying degrees of functional redundancy are likely to be found in food webs, the framework may be useful for advancing toward the reliable knowledge of biodiversity and ecosystem function relations necessary for prudent prioritization of conservation programmes. The theory presented here introduces explanation of how increasing diversity can have a negative influence on ecosystem sustainability by altering the environment for biotic interactions ‐ and there by changing functional compensability among biota ‐ under particular conditions.
Origin and evolution of primate social organisation: a reconstruction
Authors: MÜLLER ALEXANDRA E. , THALMANN URS 
Published: August 2010

ABSTRACTThe evolution and origin of primate social organisation has attracted the attention of many researchers, and a solitary pattern, believed to be present in most nocturnal prosimians, has been generally considered as the most primitive system. Nocturnal prosimians are in fact mostly seen alone during their nightly activities and therefore termed’ solitary foragers’, but that does not mean that they are not social. Moreover, designating their social organisation as’ solitary’, implies that their way of life is uniform in all species. It has, however, emerged over the last decades that all of them exhibit not only some kind of social network but also that those networks differ among species. There is a need to classify these social networks in the same manner as with group‐living (gregarious) animals if we wish to link up the different forms of primate social organisation with ecological, morphological or phylogenetic variables. In this review, we establish a basic classification based on spatial relations and sociality in order to describe and cope properly with the social organisation patterns of the different species of nocturnal prosimians and other mammals that do not forage in cohesive groups. In attempting to trace the ancestral pattern of primate social organisation, the Malagasy mouse and dwarf lemurs and the Afro‐Asian bushbabies and lorises are of special interest because they are thought to approach the ancestral conditions most closely. These species have generally been believed to exhibit a dispersed harem system as their pattern of social organisation (‘dispersed’ means that individuals forage solitarily but exhibit a social network). Therefore, the ancestral pattern of primate social organisation was inferred to be a dispersed harem. In fact, new field data on cheirogaleids combined with a review of patterns of social organisation in strepsirhines (lemurs, bushbabies and lorises) revealed that they exhibit either dispersed multi‐male systems or dispersed monogamy rather than a dispersed harem system. Therefore, the concept of a dispersed harem system as the ancestral condition of primate social organisation can no longer be supported. In combination with data on social organisation patterns in ‘primitive’ placentals and marsupials, and in monotremes, it is in fact most probable that promiscuity is the ancestral pattern for mammalian social organisation. Subsequently, a dispersed multi‐male system derived from promiscuity should be regarded as the ancestral condition for primates. We further suggest that the gregarious patterns of social organisation in Aotus and Avahi, and the dispersed form in Tarsius evolved from the gregarious patterns of diurnal primates rather than from the dispersed nocturnal type. It is consequently proposed that, in addition to Aotus and Tarsius, Avahi is also secondarily nocturnal.
Thyroid hormones and their effects: a new perspective
Authors: HULBERT A. J. 
Published: August 2010

ABSTRACTThe thyroid hormones are very hydrophobic and those that exhibit biological activity are 3′,5′,3,5‐Ltetraiodothyronine (T4), 3′,5,3‐L‐triiodothyronine (T3), 3′,5′,3‐L‐triiodothyronine (rT3) and 3,5,‐Ldiiodothyronine (3,5‐T2). At physiological pH, dissociation of the phenolic ‐OH group of these iodothyronines is an important determinant of their physical chemistry that impacts on their biological effects. When non‐ionized these iodothyronines are strongly amphipathic. It is proposed that iodothyronines are normal constituents of biological membranes in vertebrates. In plasma of adult vertebrates, unbound T4 and T3 are regulated in the picomolar range whilst protein‐bound T4 and T3 are maintained in the nanomolar range. The function of thyroid‐hormone‐binding plasma proteins is to ensure an even distribution throughout the body. Various iodothyronines are produced by three types of membrane‐bound cellular deiodinase enzyme systems in vertebrates. The distribution of deiodinases varies between tissues and each has a distinct developmental profile. Thyroid hormones have many effects in vertebrates. It is proposed that there are several modes of action of these hormones.(1) The nuclear receptor mode is especially important in the thyroid hormone axis that controls plasma and cellular levels of these hormones.(2) These hormones are strongly associated with membranes in tissues and normally rigidify these membranes.(3) They also affect the acyl composition of membrane bilayers and it is suggested that this is due to the cells responding to thyroid‐hormone‐induced membrane rigidification. Both their immediate effects on the physical state of membranes and the consequent changes in membrane composition result in several other thyroid hormone effects. Effects on metabolism may be due primarily to membrane acyl changes. There are other actions of thyroid hormones involving membrane receptors and influences on cellular interactions with the extracellular matrix. The effects of thyroid hormones are reviewed and appear to be combinations of these various modes of action. During development, vertebrates show a surge in T4 and other thyroid hormones, as well as distinctive profiles in the appearance of the deiodinase enzymes and nuclear receptors. Evidence from the use of analogues supports multiple modes of action. Re‐examination of data from the early 1960s supports a membrane action. Findings from receptor ‘knockout’ mice supports an important role for receptors in the development of the thyroid axis. These iodothyronines may be better thought of as ‘vitamone’ ‐like molecules than traditional hormonal messengers.
Chromosome evolution in the Salmonidae (Pisces): an update
Authors: PHILLIPS RUTH , RÁB PETR 
Published: August 2010

ABSTRACTThe karyotypes of salmonid fishes including taxa in the three subfamilies Coregoninae, Thymallinae and Salmoninae are described. This review is an update of the (Hartley, 1987) review of the chromosomes of salmonid fishes. As described in the previous review, the karyotypes of salmonid fishes fall into two main categories based on chromosome numbers: the type A karyotypes have diploid numbers close to 80 with approximately 100 chromosome arms (2n=80, NF=100), and the type B karyotypes have diploid numbers close to 60 with approximately 100 chromosome arms (2n=60, NF=100). In this paper we have proposed additional sub categories based on variation in the number of chromosome arms: the A″ type with NF=110‐120, the A″ type with NF greater than 140, and the B″ type with NF less than 80. Two modes of chromosome evolution are found in the salmonids: in the Coregoninae and the Salmoninae the chromosomes have evolved by centric fusions of the Robertsonian type decreasing chromosome numbers (2n) while retaining chromosome arm numbers (NF) close to that found in the hypothetical tetraploid ancestor so that most extant taxa have either type A or type B karyotypes. In the Thymallinae, the chromosomes have evolved by inversions so that chromosome arm numbers (NF) have increased but chromosome numbers (2n) close to the karyotype of the hypothetical tetraploid ancestor have been retained and all taxa have type A″ karyotypes. Most of the taxa with type B karyotypes in the Coregoninae and Salmoninae are members of the genus Oncorhynchus, although at least one example of type B karyotypes is found in all of the other genera. These taxa either have an anadromous life history or are found in specialized lacustrine environments. Selection for increases or decreases in genetic recombination as proposed by Qumsiyeh, 1994 could have been involved in the evolution of chromosome number in salmonid fishes.
Coincidence, coevolution, or causation? DNA content, cellsize, and the C‐value enigma
Authors: GREGORY T. RYAN 
Published: August 2010

ABSTRACTVariation in DNA content has been largely ignored as a factor in evolution, particularly following the advent of sequence‐based approaches to genomic analysis. The significant genome size diversity among organisms (more than 200000‐fold among eukaryotes) bears no relationship to organismal complexity and both the origins and reasons for the clearly non‐random distribution of this variation remain unclear. Several theories have been proposed to explain this ‘C‐value enigma’ (heretofore known as the ‘C‐value paradox’), each of which can be described as either a ‘mutation pressure’ or ‘optimal DNA’ theory. Mutation pressure theories consider the large portion of non‐coding DNA in eukaryotic genomes as either ‘junk’ or ‘selfish’ DNA and are important primarily in considerations of the origin of secondary DNA. Optimal DNA theories differ from mutation pressure theories by emphasizing the strong link between DNA content and cell and nuclear volumes. While mutation pressure theories generally explain this association with cell size as coincidental, thenucleoskeletaltheory proposes a coevolutionary interaction between nuclear and cell volume, with DNA content adjusted adaptively following shifts in cell size. Each of these approaches to the C‐value enigma is problematic for a variety of reasons and the preponderance of the available evidence instead favours thenucleotypictheory which postulates a causal link between bulk DNA amount and cell volume. Under this view, variation in DNA content is under direct selection via its impacts on cellular and organismal parameters. Until now, no satisfactory mechanism has been presented to explain this nucleotypic effect. However, recent advances in the study of cell cycle regulation suggest a possible ‘gene‐nucleus interaction model’ which may account for it. The present article provides a detailed review of the debate surrounding the C‐value enigma, the various theories proposed to explain it, and the evidence in favour of a causal connection between DNA content and cell size. In addition, a new model of nucleotypic influence is developed, along with suggestions for further empirical investigation. Finally, some evolutionary implications of genome size diversity are considered, and a broadening of the traditional ‘biological hierarchy’ is recommended.
Are green islands red herrings? Significance of green islands in plant interactions with pathogens and pests
Authors: Walters Dale R. , McRoberts Neil , Fitt Bruce D. L. 
Published: August 2010

AbstractThe term green island was first used to describe an area of living, green tissue surrounding a site of infection by an obligately biotrophic fungal pathogen, differentiated from neighbouring yellowing, senescent tissue. However, it has now been used to describe symptoms formed in response to necrotrophic fungal pathogens, virus infection and infestation by certain insects. In leaves infected by obligate biotrophs such as rust and powdery mildew pathogens, green islands are areas where senescence is retarded, photosynthetic activity is maintained and polyamines accumulate. We propose such areas, in which both host and pathogen cells are alive, be termed green bionissia. By contrast, we propose that green areas associated with leaf damage caused by toxins produced by necrotrophic fungal pathogens be termed green necronissia. A range of biotrophic/hemibiotrophic fungi and leaf‐mining insects produce cytokinins and it has been suggested that this cytokinin secretion may be responsible for the green island formation. Indeed, localised cytokinin accumulation may be a common mechanism responsible for green island formation in interactions of plants with biotrophic fungi, viruses and insects. Models have been developed to study if green island formation is pathogen‐mediated or host‐mediated. They suggest that green bionissia on leaves infected by biotrophic fungal pathogens represent zones of host tissue, altered physiologically to allow the pathogen maximum access to nutrients early in the interaction, thus supporting early sporulation and increasing pathogen fitness. They lead to the suggestion that green islands are ‘red herrings’, representing no more than the consequence of the infection process and discrete changes in leaf senescence.
Chronic stroke recovery after combined BCI training and physiotherapy: A case report
Authors: Caria Andrea , Weber Cornelia , Brötz Doris , Ramos Ander , Ticini Luca F. , Gharabaghi Alireza , Braun Christoph , Birbaumer Niels 
Published: August 2010

AbstractA case of partial recovery after stroke and its associated brain reorganization in a chronic patient after combined brain computer interface (BCI) training and physiotherapy is presented. A multimodal neuroimaging approach based on fMRI and diffusion tensor imaging was used to investigate plasticity of the brain motor system in parallel with longitudinal clinical assessments. A convergent association between functional and structural data in the ipsilesional premotor areas was observed. As a proof of concept investigation, these results encourage further research on a specific role of BCI on brain plasticity and recovery after stroke.
Radiofrequency ablation for selective reduction in complex monochorionic pregnancies
Authors: Paramasivam G , Wimalasundera R , Wiechec M , Zhang E , Saeed F , Kumar S 
Published: August 2010

Please cite this paper as: Paramasivam G, Wimalasundera R, Wiechec M, Zhang E, Saeed F, Kumar S. Radiofrequency ablation for selective reduction in complex monochorionic pregnancies. BJOG 2010;117:1294–1298.Monochorionic pregnancies present unique challenges for selective fetal reduction, as vaso‐occlusive procedures are required to ablate blood flow, usually in the umbilical cord, to achieve asystole in the selected fetus. We describe a case series of 35 monochorionic pregnancies (27 twins and eight triplets) undergoing selective fetal reduction using radiofrequency ablation. All procedures were performed under local anaesthesia. The procedure was technically successful in all cases. The live born rate was 88.6%. One (2.9%) woman miscarried within 2 weeks of the procedure, and two (5.7%) babies were stillborn. The median gestation at delivery was 36 weeks of gestation (range 24–41 weeks). There were no maternal complications. The median gestational age at procedure was 17 + 3 weeks (range from 12 + 5 to 27 + 4 weeks). All women had antenatal magnetic resonance imaging (MRI) post procedure. There were two (5.7%) cases of abnormal brain imaging. Our experience suggests that radiofrequency ablation is a safe and effective procedure for fetal reduction in complicated monochorionic pregnancies.