Search results for "phylogeny"
showing 10 items of 1398 documents
Population structure and reticulate evolution of Saccharomyces eubayanus and its lager-brewing hybrids
2014
Reticulate evolution can be a major driver of diversification into new niches, especially in disturbed habitats and at the edges of ranges. Industrial fermentation strains of yeast provide a window into these processes, but progress has been hampered by a limited understanding of the natural diversity and distribution of Saccharomyces species and populations. For example, lager beer is brewed with Saccharomyces pastorianus, an alloploid hybrid of S. cerevisiae and S. eubayanus, a species only recently discovered in Patagonia, Argentina. Here, we report that genetically diverse strains of S. eubayanus are readily isolated from Patagonia, demonstrating that the species is well established the…
The population genetics and evolutionary epidemiology of RNA viruses.
2004
Key Points The authors discuss the main mechanisms of RNA virus evolution — mutation, recombination, natural selection, genetic drift and migration, and how these interact to shape the genetic structure of populations.The quasispecies model of RNA virus evolution is explained and the question of whether this model provides an accurate description of RNA virus evolution is discussed.Experiments that can be carried out to test the basic principles of evolutionary theory are briefly described. The authors review what such experiments have told us about virus evolution and, more widely, what these experiments have revealed in terms of general evolutionary principles.RNA viruses evolve quickly, …
Diversity of freshwater Epsilonproteobacteria and dark inorganic carbon fixation in the sulphidic redoxcline of a meromictic karstic lake.
2015
Sulfidic redoxclines are a suitable niche for the growth and activity of different chemo- and photolithotrophic sulphide-oxidizing microbial groups such as the Epsilonproteobacteria and the green sulfur bacteria (GSB). We have investigated the diversity, abundance and contribution to inorganic carbon uptake of Epsilonproteobacteria in a meromictic basin of Lake Banyoles. CARD-FISH counts revealed that Epsilonproteobacteria were prevalent at the redoxcline in winter (maximum abundance of 2 × 10(6) cells mL(-1), ≈60% of total cells) but they were nearly absent in summer, when GSB bloomed. This seasonal trend was supported by 16S rRNA gene pyrotag datasets, which revealed that the epsilonprote…
Sequence evolution, processing, and posttranslational modification of zonadhesin D domains in primates, as inferred from cDNA data
2005
Zonadhesin is a mammalian transmembrane sperm ligand. Precursor zonadhesin essentially consists of MAM (meprin/A5 antigen/mu receptor tyrosine phosphatase) domains, a mucin-like repeat, and D domains (homologous to von Willebrand D). Recent immunovisualization and binding assays indicate that zonadhesin D domains 1–3 bind postacrosomally to the zona pellucida. This feature has attracted considerable interest in the evolution of zonadhesin and its possible biological and biomedical implications. Previous molecular evolutionary analyses, however, were confined to cDNA sequences of only few distantly related species. Moreover, except for rabbit and pig, little is known about zonadhesin’s proce…
Anatomical Network Analysis Shows Decoupling of Modular Lability and Complexity in the Evolution of the Primate Skull
2015
Modularity and complexity go hand in hand in the evolution of the skull of primates. Because analyses of these two parameters often use different approaches, we do not know yet how modularity evolves within, or as a consequence of, an also-evolving complex organization. Here we use a novel network theory-based approach (Anatomical Network Analysis) to assess how the organization of skull bones constrains the co-evolution of modularity and complexity among primates. We used the pattern of bone contacts modeled as networks to identify connectivity modules and quantify morphological complexity. We analyzed whether modularity and complexity evolved coordinately in the skull of primates. Specifi…
Eggshell types and their evolutionary correlation with life-history strategies in squamates
2015
The eggshell is an important physiological structure for the embryo. It enables gas exchange, physical protection and is a calcium reserve. Most squamates (lizards, snakes, worm lizards) lay parchment-shelled eggs, whereas only some gekkotan species, a subgroup of lizards, have strongly calcified eggshells. In viviparous (live-bearing) squamates the eggshell is reduced or completely missing (hereafter “shell-less”). Recent studies showed that life-history strategies of gekkotan species differ between species with parchment- and rigid-shelled eggshells. Here we test if the three different eggshell types found in the squamates are also associated with different life-history strategies. We fir…
Functional characterization of two melanocortin (MC) receptors in lamprey showing orthology to the MC1 and MC4 receptor subtypes
2007
Abstract Background The melanocortin (MC) receptors have a key role in regulating body weight and pigmentation. They belong to the rhodopsin family of G protein-coupled receptors (GPCRs). The purpose of this study was to identify ancestral MC receptors in agnathan, river lamprey. Results We report cloning of two MC receptors from river lamprey. The lamprey receptors, designated MCa and MCb, showed orthology to the MC1 and MC4 receptor subtypes, respectively. The molecular clock analysis suggested that lamprey MC receptor genes were not duplicated recently and diverged from each other more than 400 MYR ago. Expression and pharmacological characterization showed that the lamprey MCa receptor …
Phylogenetic relationship among genera of Polymorphidae (Acanthocephala), inferred from nuclear and mitochondrial gene sequences.
2013
Abstract Acanthocephalans of the family Polymorphidae Meyer, 1931 are obligate endoparasites with complex life cycles. These worms use vertebrates (marine mammals, fish-eating birds and waterfowl) as definitive hosts and invertebrates (amphipods, decapods and euphausiids) as intermediate hosts to complete their life cycle. Polymorphidae has a wordwide distribution, containing 12 genera, with approximately 127 species. The family is diagnosed by having a spinose trunk, bulbose proboscis, double-walled proboscis receptacle, and usually four to eight tubular cement glands. To conduct a phylogenetic analysis, in the current study sequences of the small (18S) and large-subunit (28S) ribosomal RN…
Evidence for an instructive role of apoptosis during the metamorphosis of Hydractinia echinata (Hydrozoa)
2011
Apoptosis is a highly conserved mechanism of cell deletion that destroys redundant, dysfunctional, damaged, and diseased cells. Furthermore, apoptotic cell death is essential during the development of multicellular organisms. However, there are only a few examples where the occurrence of apoptosis has been shown to be a direct prerequisite for developmental processes. As described previously by our group, the degradation of larval tissue during the first half of the metamorphosis of Hydractinia echinata involves extensive cell death. A large number of cells are removed, and we observed several cellular features of apoptotic cell death in the dying tissue, e.g., nucleosomal DNA fragmentation…
Origin of the prolactin-releasing hormone (PRLH) receptors: evidence of coevolution between PRLH and a redundant neuropeptide Y receptor during verte…
2004
We present seven new vertebrate homologs of the prolactin-releasing hormone receptor (PRLHR) and show that these are found as two separate subtypes, PRLHR1 and PRLHR2. Analysis of a number of vertebrate sequences using phylogeny, pharmacology, and paralogon analysis indicates that the PRLHRs are likely to share a common ancestry with the neuropeptide Y (NPY) receptors. Moreover, a micromolar level of NPY was able to bind and inhibit completely the PRLH-evoked response in PRLHR1-expressing cells. We suggest that an ancestral PRLH peptide started coevolving with a redundant NPY binding receptor, which then became PRLHR, approximately 500 million years ago. The PRLHR1 subtype was shown to have…