Ancestral Forms (ancestral + form)

Distribution by Scientific Domains

Selected Abstracts

Biochemistry and molecular biology of lithotrophic sulfur oxidation by taxonomically and ecologically diverse bacteria and archaea

Wriddhiman Ghosh
Abstract Lithotrophic sulfur oxidation is an ancient metabolic process. Ecologically and taxonomically diverged prokaryotes have differential abilities to utilize different reduced sulfur compounds as lithotrophic substrates. Different phototrophic or chemotrophic species use different enzymes, pathways and mechanisms of electron transport and energy conservation for the oxidation of any given substrate. While the mechanisms of sulfur oxidation in obligately chemolithotrophic bacteria, predominantly belonging to Beta - (e.g. Thiobacillus) and Gammaproteobacteria (e.g. Thiomicrospira), are not well established, the Sox system is the central pathway in the facultative bacteria from Alphaproteobacteria (e.g. Paracoccus). Interestingly, photolithotrophs such as Rhodovulum belonging to Alphaproteobacteria also use the Sox system, whereas those from Chromatiaceae and Chlorobi use a truncated Sox complex alongside reverse-acting sulfate-reducing systems. Certain chemotrophic magnetotactic Alphaproteobacteria allegedly utilize such a combined mechanism. Sulfur-chemolithotrophic metabolism in Archaea, largely restricted to Sulfolobales, is distinct from those in Bacteria. Phylogenetic and biomolecular fossil data suggest that the ubiquity of sox genes could be due to horizontal transfer, and coupled sulfate reduction/sulfide oxidation pathways, originating in planktonic ancestors of Chromatiaceae or Chlorobi, could be ancestral to all sulfur-lithotrophic processes. However, the possibility that chemolithotrophy, originating in deep sea, is the actual ancestral form of sulfur oxidation cannot be ruled out. [source]

Taxonomy, evolutionary History and Distribution of the middle to late Famennian Wocklumeriina (Ammonoidea, Clymeniida)

R. Thomas Becker
Abstract Old collections, new records, and data from global literature are used for taxonomic revisions and for a new reconstruction of the evolutionary history of the triangularly coiled clymenids, the Wocklumeriaceae, and their ancestors. Epiwocklumeria applanata is first reported from the topmost Wocklum Limestone at Hasselbachtal and Drewer, and this supports the distinction of an applanata Subzone just prior to the global Hangenberg Event which wiped out the whole group. The Wocklumeriaceae and Glatziellidae record of the famous Oberrödinghausen Railway Cut and of other Rhenish sections is revised. The Maïder of Southern Morocco has yielded first Parawocklumeria patens, paprothae, Wocklumeria sphaeroides plana, Kielcensia ingeniens n. sp., and Synwocklumeria mapesi n. sp. Parawocklumeria distributa Czarnocki forms the type-species of Tardewocklumeria n. gen. Lecto- and neotypes for several taxa are designated. The variability and paedomorphic patterns of Wo. sphaeroides are discussed. The Wocklumeriaceae represent the terminal Famennian (Upper Devonian VI-C/D) radiation of a long-ranging lineage which evolved in parallel to other clymenid groups. They are characterized by sutural features and by longidomic and very slowly expanding whorls. The polyphyletic traditional Gonioclymeniina are divided into the suborder Wocklumeriina (with Wocklumeriaceae, Glatziellaceae n.superfam. and Biloclymeniaceae) and into the Gonioclymeniaceae of the Clymeniina. Gyroclymenia Czarnocki is regarded as a junior synonym of Pleuroclymenia Schindewolf which, however, does not include the ,Pleuro.' americana and eurylobica groups. Pleuroclymenia represents the ancestral form of the Wocklumeriina and also the phylogenetical link with Platyclymenia (Varioclymenia) of the Clymeniaceae. The Gonioclymeniaceae had their roots in advanced Platyclymeniidae. Alte Aufsammlungen, Neunachweise und globale Literaturdaten werden für taxonomische Revisionen und für eine neue Rekonstruktion der Evolution der Dreiecksclymenien (Wocklumeriaceae) und ihrer Vorfahren benutzt. Epiwocklumeria applanata wird zum ersten Mal im Hasselbachtal und bei Drewer nachgewiesen, und diese Funde bestätigen die Abtrennung einer applanata -Subzone im unmittelbar Liegenden des Hangenberg-Event, welcher zum Aussterben der gesamten Gruppe führte. Die Verbreitung von Wocklumeriaceae und Glatziellidae im klassischen Profil des Bahneinschnittes bei Oberrödinghausen und an anderen Fundorten im Rheinischen Schiefergebirge wird revidiert. Der Maïder in Süd-Marokko lieferte erstmalig Parawocklumeria patens, paprothae, Wocklumeria sphaeroides plana, Kielcensia ingeniens n. sp. und Synwocklumeria mapesi n. sp. Parawocklumeria distributa Czarnocki bildet die Typus-Art von Tardewocklumeria n.gen. Weiterhin werden die Variabilität und paedomorphe Erscheinungen bei Wo. sphaeroides diskutiert. Die Wocklumeriaceae repräsentieren im höchsten Famennium (UD VI-C/D) die Radiationsphase einer langlebigen phylogenetischen Linie, die sich parallel zu anderen Clymenien entwickelte. Sie ist durch Suturmerkmale und lange Wohnkammern bei niedrigmündigen Gehäusen charakterisiert. Die als polyphyletisch erkannten Gonioclymeniina werden in die Wocklumeriina (mit Wocklumeriaceae, Glatziellaceae n.superfam. und Biloclymeniaceae) und in die Gonioclymeniaceae der Clymeniina geteilt. Gyroclymenia Czarnocki ist ein jüngeres Synonym von Pleuroclymenia Schindewolf, umfasst jedoch nicht die ,Pleuro.' americana -und ,Pleuro.' eurylobica -Artgruppen. Die Gattung ist die ursprünglichste Form der Wocklumeriina und stellt gleichzeitig das Bindeglied zu Platyclymenia (Varioclymenia) der Clymeniaceae dar. Die Gonioclymeniaceae wurzeln in fortgeschrittenen Platyclymeniidae. [source]

Gut content analysis and a new feeding group classification of termites

S. E. Donovan
Summary 1. Gut content analysis of termites was undertaken using microscopical techniques. The 46 study species covered the entire range of taxonomic and feeding forms within the Order. 2. Inter-specific gut contents data were analysed using principal components analysis, placing species along a clear humification gradient based on variations in the amount of silica and plant tissue fragments in the gut. 3. Redundancy analysis was used to find morphological correlates of the observed variation in gut contents. A total of 22 morphological characters (out of 45 candidate characters) were correlated significantly with the gut contents. 4. Three of the 22 significantly correlated characters unambiguously defined feeding groups, which were designated groups I to IV in increasing order of humification of the feeding substrate. Group I contains lower termite dead wood and grass-feeders; group II contains Termitidae with a range of feeding habits including dead wood, grass, leaf litter, and micro-epiphytes; group III contains Termitidae feeding in the organic rich upper layers of the soil; group IV contains the true soil-feeders (again all Termitidae), ingesting apparently mineral soil. These groupings were generally supported statistically in a canonical covariance analysis, although group II apparently represents termite species with a rather wide range of feeding habits. 5. Using existing hypotheses of termite phylogenetic relationships, it seems probable that group I feeders are phylogenetically basal, and that the other groupings have arisen independently on a number of occasions. Soil-feeding (i.e. group III and group IV feeding) may have evolved due to the co-option of faecal material as a fungal substrate by Macrotermitinae-like ancestral forms. As a consequence, these forms would have been constrained to build nest structures from soil and would therefore have passed at least some soil through their guts. [source]

Population genetics of Escherichia coli in a natural population of native Australian rats

Gulietta M. Pupo
Escherichia coli, a normal inhabitant of the intestinal tract of mammals and birds, is a diverse species. Most studies on E. coli populations involve organisms from humans or human-associated animals. In this study, we undertook a survey of E. coli from native Australian mammals, predominantly Rattus tunneyi, living in a relatively pristine environment in the Bundjalung National Park. The genetic diversity was assessed and compared by multilocus enzyme electrophoresis (MLEE), sequence analysis of the mdh (malate dehydrogenase) gene and biotyping using seven sugars. Ninety-nine electrophoretic types were identified from the 242 isolates analysed by MLEE and 15 sequences from the mdh genes sequenced from 21 representative strains. The Bundjalung isolates extend the diversity represented by the E. coli reference (ECOR) set, with new MLEE alleles found in six out of 10 loci. Many of the Bundjalung isolates fell into a discrete group in MLEE. Other Bundjalung strains fell into the recognized E. coli ECOR set groups, but tended to be at the base of both the MLEE and mdh gene trees, implying that these strains are derived independently from ancestral forms of the ECOR groups and that ECOR strains represent only a subset of E. coli adapted to humans and human-associated animals. Linkage disequilibrium analysis showed that the Bundjalung population has an ,epidemic' population structure. The Bundjalung isolates were able to utilize more sugars than the ECOR strains, suggesting that diet plays a prominent role in adaptation of E. coli. [source]

Reproductive hierarchies in the African allodapine bee Allodapula dichroa (Apidae: Xylocopinae) and ancestral forms of sociality

The social organization of allodapine bees has been described in detail for most genera, although there remains a notable gap for one major lineage, the genus Allodapula. Here, we provide the first detailed study of social organization in Allodapula dichroa. Colony sizes are small and the frequency of cooperative nesting is low compared with other allodapine taxa, but there is very clear evidence for reproductive differentiation among adult nestmates. Reproductively dominant females tend to be larger than their nestmates and have much higher levels of wing wear, suggesting that they perform most foraging activities. Multi-female colonies have: (1) lower rates of complete brood absence, suggesting a substantial benefit to cooperative nesting; and (2) larger numbers of brood, suggesting that the presence of a second adult female leads to a greater reproductive output. These data suggest a major phylogenetic split in the form of social organization within the allodapines. In the genus Macrogalea (sister clade to all other allodapines), body size does not preclude young females from laying eggs, and there appears to be, at most, weak reproductive queues. However, in most other allodapines, reproductive hierarchies are prominent and younger and/or smaller females queue for reproductive opportunities, adopt permanently subordinate roles, or disperse. Interestingly, the most common forms of reproductive hierarchies in allodapines do not involve subordinates undertaking foraging roles before reproduction, but instead involve the delaying of both reproduction and foraging. This has implications for the understanding of suggested developmental ground plans in the early stages of social evolution. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 520,530. [source]