Search results for "PHYLOGENE"
showing 10 items of 1189 documents
Are homalozoans echinoderms? An answer from the extraxial-axial theory
2000
Homalozoans include four classes of non-pentamerous Paleozoic echinoderms: Homostelea (cinctans), Ctenocystoidea (ctenoid-bearing homalozoans), Homoiostelea (solutes), and Stylophora (cornutes and mitrates). Their atypical morphologies have historically made it difficult to relate them to other classes. Therefore, their systematic positions have been represented by two hypotheses (H): as stem taxa to echinoderms (H1) or as stem taxa to chordates (H2). These conclusions rest on previous inability to recognize synapomorphies with more crownward echinoderms, resulting in a forcing of the homalozoans down the phylogenetic tree that is more artifactual than evolutionary. The Extraxial-Axial Theo…
Phylogeny and origin of Jurassic irregular echinoids (Echinodermata: Echinoidea).
2006
27 pages; International audience; A phylogenetic analysis of Jurassic irregular echinoids is realized to explore the origin and early evolution of this important subset of echinoids. The phylogeny is based on 39 characters and considers data from apical system architecture, the corona including tuberculation and spines, Aristotle's lantern, and general test shape. Results corroborate the monophyly of Irregularia, and clarify the phylogenetic interrelationships existing between the main groups of irregular echinoids. Specializations of the Aristotle's lantern, spines, tubercles and phyllodes constitute the apomorphies for different taxa, as for the whole of Irregularia. The phylogenetic sign…
Phylogeny and species limits in the Palaearctic chiffchaffPhylloscopus collybitacomplex: mitochondrial genetic differentiation and bioacoustic eviden…
1996
Nucleotide sequences of the mitochondrial cytochrome b gene (1041 bp), analysis of vocalizations and behavioural evidence from zones of contact were used to reassess the species limits and phylogenetic relationships at the species and subspecies levels in the Phylloscopus collybita complex. A new classification is proposed which recognizes four biological species. Phylloscopus brehmii (Iberia) and P. canariensis (Canary Islands) are genetically and bioacoustically highly distinct. There is no mitochondrial gene flow between them or with P. collybita. The Mountain Chiffchaff P. sindianus (with subspecies sindianus and Iorenzii) is equally distinct genetically from southwest Asian subspecies …
18S rDNA phylogeny and evolution of cap development in Polyphysaceae (formerly Acetabulariaceae; Dasycladales, Chlorophyta)
2003
Abstract Cells of the members of the Dasycladales have a unique body plan well known from fossils. They persist today in 38 recognized species. This study investigates in detail the development of reproductive structures in 17 Polyphysaceae (= Acetabulariaceae) species and provides a molecular phylogenetic analysis of 18S ribosomal DNA sequence data of 23 species of the order Dasycladales, including 17 of the 19 extant members of the family Polyphysaceae. Reproductive cap development is documented by scanning electron microscopy in 17 species, by histological sections in five species, and by growth measurements. Other morphometric data are also provided for most species. Bayesian analysis o…
One is not enough: On the effects of reference genome for the mapping and subsequent analyses of short-reads.
2020
Mapping of high-throughput sequencing (HTS) reads to a single arbitrary reference genome is a frequently used approach in microbial genomics. However, the choice of a reference may represent a source of errors that may affect subsequent analyses such as the detection of single nucleotide polymorphisms (SNPs) and phylogenetic inference. In this work, we evaluated the effect of reference choice on short-read sequence data from five clinically and epidemiologically relevant bacteria (Klebsiella pneumoniae, Legionella pneumophila, Neisseria gonorrhoeae, Pseudomonas aeruginosa and Serratia marcescens). Publicly available whole-genome assemblies encompassing the genomic diversity of these species…
The evolutionary trend of platform denticulation in Middle Triassic acuminate Gondolellidae (Conodonta)
2017
Kılıç, Ali Murat (Balikesir Author)
The Pleistocene subterranean volesTerricola (Rodentia) of Serbia and Montenegro
2001
A general morphometrical analysis of the M1 was conducted to identify the subterranean vole species found in Upper Pleistocene localities from Serbia and Montenegro, and to clarify the systematic position and the phylogenetic relationships between the different species in the Balkans. From the different localities studied, we can assign one population toMicrotus (Terricola) thomasi and the others to theM. (T.) subterraneus group. This study suggests thatM. (T.) grafi can be considered as a chronological sub-species ofM. (T.) subterraneus or as a different but phylogenetically very close species.
Evolutionary history of treecreeper vocalisations (Aves: Certhia)☆
2008
AbstractSince the vocalisations of passerine birds are in general a good means to separate taxa when external morphological differences are few, song and call recordings of 33 treecreeper (Certhia) taxa were sonagraphed and their parameters analysed. The vocalisations show low intra-individual and intra-population variation. Phylogenetic evolutionary units at the population level were delimited by time, frequency and syntax parameters by means of principal-component and discriminant analyses. Traits of territorial song were traced on a phylogenetic tree based on cytochrome b sequences, and a mean acoustic character difference was calculated. All presently recognised nine species could be di…
The role of hybridization in the evolution ofCousinias.str.(Asteraceae, Cardueae)
2009
Abstract Mehregan I. & Kadereit J. W.: The role of hybridization in the evolution of Cousinia s.str. (Asteraceae, Cardueae). — Willdenowia 39: 35–47. — Online ISSN 1868-6397; © 2009 BGBM Berlin-Dahlem. doi:10.3372/wi.39.39102 (available via http://dx.doi.org/) In order to assess the possible role of interspecific hybridization for the evolution of the high diversity of Cousinia subg. Cousinia (Cousinia s.str., c. 600 species), we examined the frequency of hybridization in this taxon. For this, hypothetical hybrid combinations published in the literature (28 putative hybrids and 11 intermediate forms) were critically examined. In addition, two hybrids were identified in the present study by …