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Phylogenetic Aspects (phylogenetic + aspect)
Selected AbstractsThe circulatory system in Chilopoda: functional morphology and phylogenetic aspectsACTA ZOOLOGICA, Issue 3 2002Christian S. Wirkner Abstract The circulatory organs of nine representative species of all five chilopod orders were examined by light microscopy and by in vivo observations of haemolymph flow. In Scutigera coleoptrata, the heart ultrastructure was studied. The circulatory system in Craterostigmomorpha is described for the first time. Further focus is placed on the Geophilomorpha since previous descriptions in this group have been only superficial. In all investigated species, the circulatory system consists of two longitudinal central vessels which are connected in the first body segment by the maxilliped arch. The posterior part of these vessels is contractile and thus haemolymph is pumped anteriorly in the heart, while it is pumped posteriorly in the supraneural vessel. From these central vessels numerous peripheral vessels branch off. Differences among the chilopod orders lie mainly in the distribution of the peripheral vessels. The circulatory system in Scutigeromorpha shows some striking morphological adaptations with regard to the functional coupling of circulatory and respiratory tasks. The most peculiar structures are the aortic diverticles which act as accessory pumps in the head. Phylogenetic analysis of the circulatory organ traits within Chilopoda supports the Pleurostigmophora hypothesis. Synapomorphies supporting the Myriapoda hypothesis or the Tracheata concept were not found. [source] Dentition in the African catfishes Andersonia (Amphiliidae) and Siluranodon (Schilbeidae) previously considered toothlessJOURNAL OF FISH BIOLOGY, Issue 1 2004A. S. Golubtsov Based on light and scanning electron microscopic examination of their morphology, the dentition on both the premaxilla and dentary of Andersonia(Amphiliidae) and Siluranodon(Schilbeidae) catfishes is described from samples taken from tributaries of the White Nile in south-western Ethiopia. These monotypic African genera were previously believed to lack teeth on the lower jaw in Andersonia and on both jaws in Siluranodon. Siluranodon exhibits an ontogenetic reduction: teeth were less frequently found in larger individuals than in smaller ones. In contrast to the adults of all other schilbeids, whose oral teeth are arranged in multiserial (or at least, biserial) bands, Siluranodon has uniserial teeth on both the premaxilla and the dentary. The adaptive, ontogenetic and phylogenetic aspects of jaw-tooth reduction in catfishes are discussed. [source] Cellulose structure and biosynthesis: What is in store for the 21st century?JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2004R. Malcolm Brown Jr. Abstract This article briefly summarizes historical developments in fundamental research related to the structure and biosynthesis of cellulose. Major advances concerning the structure of cellulose include the discovery of a new suballomorph of cellulose I, the lattice imaging of glucan chains showing no fringe micelle structure, parallel chain orientation in cellulose I, and the discovery of nematic ordered cellulose. Major advances in biosynthesis include the discovery of the terminal synthesizing complex, the isolation and purification of cellulose synthase, the in vitro synthesis of cellulose I, and synthetic cellulose assembly. This article focuses on recent advances in molecular biology with cellulose, including the cloning and sequencing of cellulose synthase genes from bacteria, cyanobacteria, and vascular plants; proof of the terminal synthesizing complex as the site of the catalytic subunit of cellulose synthase; cellulose and callose synthase expression during growth and development; and phylogenetic aspects of cellulose synthase evolution. This article concludes with thoughts about future uses for the accumulating genetic information on cellulose biosynthesis for textiles and forest products and discusses possibilities of new global resources for cellulose production. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 487,495, 2004 [source] Larval chaetotaxy of Coleoptera (Insecta) as a tool for evolutionary research and systematics: less confusion, more clarityJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2007A. Y. Solodovnikov Abstract Chaetotaxy of beetle larvae is a significant source of characters for descriptive and phylogenetic aspects of systematics of this largest group of animals of comparable age. Survey of the mostly modern systematic literature employing larval chaetotaxy in Coleoptera reveals, however, that contrary to some general claims for the utility of this character set, use of larval chaetotaxy is rather limited. This is mostly because researchers find working with larval chaetotaxy difficult and time consuming. Factors that make exploration of chaetotaxy so cumbersome are methodologically analysed here and divided into two categories: intrinsic and operational. It is revealed that the most dangerous of them are operational, which arise from the multiplication of inconsistencies coming from different levels of comparative morphological research. As a result, ill-defined assessments of larval chaetotaxy may bring more confusion than clarity to the systematics of beetles, especially to its phylogenetic component which is intuitively avoided by researchers who refuse to use chaetotaxy. This paper attempts to scrutinize the sources of these inconsistencies undermining studies of larval chaetotaxy in hope of eliminating them from present and future systematic studies of Coleoptera. Some methodological issues raised here are also applicable to adult Coleoptera, to other insects and invertebrates, or to the proper ways of exploring the comparative morphology of living organisms, underlying evolutionary and systematic research. Zusammenfassung Die larvale Chaetotaxie von Käfern stellt wichtige Merkmale für deskriptive und phylogenetische Aspekte der Systematik dieser größten Tiergruppe zur Verfügung. Die Auswertung überwiegend moderner systematischer Schriften, in denen larvale Chaetotaxie bei Käfern angewendet wird, hat jedoch ergeben, dass, entgegen der allgemeinen Behauptung der Nützlichkeit dieses Merkmalskomplexes, dessen tatsächliche Anwendung recht begrenzt bleibt. Dies rührt haupsächlich daher, dass larvale Chaetotaxie als schwierig und zeitraubend angesehen wird. Die Faktoren, welche chaetotaxonomische Untersuchungen erschweren, werden hier methodologisch analysiert und in zwei Gruppen unterteilt: intrinsische Faktoren und operationale Faktoren. Es wird aufgezeigt, dass die operationalen Faktoren die größten Gefahren mit sich bringen, bedingt durch die Multiplikation widersprüchlicher Befunde von verschiedenen Ebenen vergleichend-morphologischer Forschung. Als Resultat können fehlgeleitete Bewertungen larvaler Chaetotaxie mehr zur Verwirrung als zur Aufklärung der Käfersystematik beitragen. Dies trifft insbesondere auf die phylogenetische Komponente der Systematik zu, die von Forschern, welche die Verwendung der Chaetotaxie ablehnen, intuitiv gemieden wird. Die vorliegende Arbeit versucht, die Quellen der widersprüchlichen Befunde zu ergründen, welche den Wert von Untersuchungen zur larvalen Chaetotaxie untergraben, sodass sie in aktuellen und zukünftigen systematisch-coleopterologischen Untersuchungen vermieden werden können. Einige der hier erörterten methodologischen Gesichtspunkte sind auch anwendbar auf adulte Käfer, andere Insekten und Wirbellose oder allgemein auf die korrekte Vorgehensweise bei der Erforschung der vergleichenden Morphologie lebender Organismen, die der Systematik und Evolutionsforschung zugrunde liegen. [source] Distinctive features in the SelB family of elongation factors for selenoprotein synthesis.BIOFACTORS, Issue 1-4 2001A glimpse of an evolutionary complexified translation apparatus Abstract The last ten years have seen a dramatic increase in our understanding of the molecular mechanism allowing specific incorporation of selenocysteine into selenoproteins. Whether in prokaryotes or eukaryotes, this incorporation requires several gene products, among which the specialized elongation factor SelB and the tRNASec play a pivotal role. While the molecular actors have been discovered and their role elucidated in the eubacterial machinery, recent data from our and other laboratories pointed to a higher degree of complexity in archaea and eukaryotes. These findings also revealed that more needs to be discovered in this area. This review will focus on phylogenetic aspects of the SelB proteins. In particular, we will discuss the concerted evolution that occurred within the SelB/tRNASec couples, and also the distinctive roles carried out by the SelB C-terminal domains in eubacteria on the one side, and archaea and eukaryotes, on the other. [source] Sex pheromones and trail-following pheromone in the basal termites Zootermopsis nevadensis (Hagen) and Z. angusticollis (Hagen) (Isoptera: Termopsidae: Termopsinae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2010CHRISTIAN BORDEREAU In the context of an evolutionary study of the chemical communication in termites, sex pheromones and trail-following pheromones were investigated in two Termopsidae, Zootermopsis nevadensis and Z. angusticollis. In these species, in which the presence of sex-specific pheromones has been demonstrated previously, the chemical structure of the female sex pheromone has now been identified as (5E)-2,6,10-trimethylundeca-5,9-dienal and the male sex pheromone as (+)- or (,)- syn -4,6-dimethyldodecanal. The amount of sex pheromone was estimated at 5,10 ng per individual in females and 2,5 ng in males. Because these two sympatric species do not differ in their pheromonal chemical composition, reproductive isolation is probably mediated chiefly by differences in dispersal flight chronology. The trail-following pheromone was shown to be composed of the same compound as the male sex pheromone, that is syn -4,6-dimethyldodecanal. The compound syn -4,6-dimethyldodecanal was 10 times more active than the racemic (+/,)- syn + (+/,) -anti -4,6-dimethyldodecanal in eliciting trail-following. The amount of syn -4,6-dimethyldodecanal was estimated at 0.1,0.5 ng per pseudergate. Regarding the phylogenetic aspects, the nature of the female sex pheromone of Zootermopsis is structurally akin to the trail-following pheromone of Mastotermes darwiniensis of Mastotermitidae and Porotermes adamsoni and Stolotermes victoriensis of Termopsidae. Interestingly, the nature of the trail-following pheromone of the Termopsinae Zootermopsis is clearly different from that of the Porotermitinae P. adamsoni and the Stolotermitinae S. victoriensis, which mirrors recent molecular data on the paraphyly of Termopsidae. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 519,530. [source] Extending phylogenetic studies of coevolution: secondary Brooks parsimony analysis, parasites, and the Great ApesCLADISTICS, Issue 2 2003Daniel R Brooks Dowling recently compared the empirical properties of Brooks parsimony analysis (BPA) and the leading method for studying phylogenetic aspects of coevolution, reconciled tree analysis (using the computer program TreeMap), based on a series of simulations. Like the majority of authors who have compared BPA with other methods, however, Dowling considered only the form of BPA proposed in 1981 and did not take into account various modifications of the method proposed from 1986 to 2002. This leaves some doubt as to the robustness of his assessments of both the superiority of BPA and its shortcomings. We provide a précis of the principles of contemporary BPA, including ways to implement it algorithmically, using either Wagner algorithm-based or Hennigian argumentation-based approaches, followed by an empirical example. Our study supports Dowling's fundamental conclusions about the superiority of primary BPA relative to TreeMap. However, his conclusions about the shortcomings of BPA due to inclusive ORing (i.e., the production of ghost taxa) are incorrect, as secondary BPA eliminates inclusive ORing from the method. Secondary BPA provides a more complete account of the evolutionary associations between the parasite groups and their hosts than does primary BPA, without sacrificing any indirectly generated information about host phylogeny. Secondary BPA of two groups of nematodes inhabiting Great Apes shows that TreeMap analysis underestimated the amount of cospeciation in the evolution of the nematode genus Enterobius. [source] | ||||||||||