游仆目纤毛虫(纤毛门,旋唇纲)的分子系统学研究

在最新GenBank分子信息的汇集、分析基础上,利用小亚基单位核糖体RNA基因序列分别构建了最大简约树、距离树、最大似然树及贝叶斯树,对长期存在争议的游仆目纤毛虫的系统关系进行了探讨和修订.工作显示:1)游仆目不是1个单源发生系;2)盘头虫类从游仆目中较早分化出来,呈现与排毛类、寡毛类平行的进化关系;3)腹棘虫科内的腹棘虫和拟游仆虫体现了密切的亲缘关系;4)游仆虫科、舍太虫科、檐纤虫科在所有分子树中均表现了十分稳定的拓扑结构;5)游仆虫属内可以细分为7个亚类群;6)尾刺虫科在游仆目内分化较早,支持前人有关其在系统演化时序中处于原始阶段的论断.     

四核舍太虫的细胞发生学与Helix E10-1二级结构分析

利用蛋白银染色技术,观察和研究海洋游仆虫-四核舍太虫Certesia quadrinucleata(纤毛门,游仆目)二分裂期间的形态发生学。其主要特征如下:(1)老口围带完全被前仔虫继承;(2)后仔虫口原基独立产生于皮膜深层;(3)老口侧膜参与前仔虫口侧膜原基形成,前后仔虫的口侧膜原基均发生于细胞表面, 向前贡献出第一根额腹棘毛;(4)额-腹-横棘毛以初级5原基模式产生, 且以"3:3:3:3:3"的方式分化出新的棘毛;(5)背触毛与左缘棘毛原基均来自老结构, 无尾棘毛产生。研究首次给出了背面纤毛器的发生图示,为进一步探讨舍太虫的系统地位提供了一份补足性的发生学基础资料。游仆目纤毛虫的核糖体小亚基基因HelixE10-1区域二级结构一共存在9种模式, 该区域序列长度的变异性揭示了游仆目纤毛虫在进化中可能处于比较特殊的地位。       

Assessing whether alpha-tubulin sequences are suitable for phylogenetic reconstruction of Ciliophora with insights into its evolution in euplotids

The current understanding of ciliate phylogeny is mainly based on analyses of a single gene, the small subunit ribosomal RNA (SSU-rDNA). However, phylogenetic trees based on single gene sequence are not reliable estimators of species trees, and SSU-rDNA genealogies are not useful for resolution of some branches within Ciliophora. Since congruence between multiple loci is the best tool to determine evolutionary history, we assessed the usefulness of alpha-tubulin gene, a protein-coding gene that is frequently sequenced, for ciliate phylogeny. Here, we generate alpha-tubulin gene sequences of 12 genera and 30 species within the order Euplotida, one of the most frequently encountered ciliate clades with numerous apparently cosmopolitan species, as well as four genera within its putative sister order Discocephalida. Analyses of the resulting data reveal that: 1) the alpha-tubulin gene is suitable phylogenetic marker for euplotids at the family level, since both nucleotide and amino acid phylogenies recover all monophyletic euplotid families as defined by both morphological criteria and SSU-rDNA trees; however, alpha-tubulin gene is not a good marker for defining species, order and subclass; 2) for seven out of nine euplotid species for which paralogs are detected, gene duplication appears recent as paralogs are monophyletic; 3) the order Euplotida is non-monophyletic, and the family Uronychiidae with sequences from four genera, is non-monophyletic; and 4) there is more genetic diversity within the family Euplotidae than is evident from dargyrome (geometrical pattern of dorsal "silverline system" in ciliates) patterns, habit and SSU-rDNA phylogeny, which indicates the urgent need for taxonomic revision in this area.     

The Order Euplotida (Ciliophora): Taxonomy, with Division of Euplotes into Several Genera

ABSTRACT. The order Euplotida represents a monophyletic order of five families of hypotrich ciliates united by morphology, stomatogenesis, ultrastructure, cyst structure, and behavior. A review of variability of ciliation and nuclei among the 14 genera suggests that lines of evolution may have involved both the loss of cirri and nuclear simplification. We present a binary key to genera in the families Aspidiscidae ( Aspidisca and Euplotaspis ), Certesiidae n. fam. ( Certesia ), Gastrocirrhidae ( Cytharoides, Euplotidium , and Gas-trocirrhus ), Uronychiidae ( Diophryopsis, Diophrys, Paradiophrys , and Uronychia ), and Euplotidae. The latter family contains species formerly in the genus Euplotes. Based primarily on cortical structure, endosymbionts, data from morphometric analysis, and ecology, we recognize four different groups. The first group of species remains in Euplotes with Euplotes charon as type. We place a second group of species into the genus Moneuplotes Jankowski 1979 with Moneuplotes vannus (Müller, 1786) as type. We erect two new genera: Euplotoides n. g. and Euplotopsis n. g. with Euplotoides patella (Müller, 1773) n. comb. and Euplotopsis affinis (Dujardin, 1841) n. comb. as type species respectively. We discuss possible phylogenetic relationships within the order.     

Reconsideration of systematic relationships within the order Euplotida (Protista, Ciliophora) using new sequences of the gene coding for small-subunit rRNA and testing the use of combined data sets to construct phylogenies of the Diophrys-complex

Comprehensive molecular analyses of phylogenetic relationships within euplotid ciliates are relatively rare, and the relationships among some families remain questionable. We performed phylogenetic analyses of the order Euplotida based on new sequences of the gene coding for small-subunit RNA (SSrRNA) from a variety of taxa across the entire order as well as sequences from some of these taxa of other genes (ITS1-5.8S-ITS2 region and histone H4) that have not been included in previous analyses. Phylogenetic trees based on SSrRNA gene sequences constructed with four different methods had a consistent branching pattern that included the following features: (1) the “typical” euplotids comprised a paraphyletic assemblage composed of two divergent clades (family Uronychiidae and families Euplotidae–Certesiidae–Aspidiscidae–Gastrocirrhidae), (2) in the family Uronychiidae, the genera Uronychia and Paradiophrys formed a clearly outlined, well-supported clade that seemed to be rather divergent from Diophrys and Diophryopsis, suggesting that the Diophrys-complex may have had a longer and more separate evolutionary history than previously supposed, (3) inclusion of 12 new SSrRNA sequences in analyses of Euplotidae revealed two new clades of species within the family and cast additional doubt on the present classification of genera within the family, and (4) the intraspecific divergence among five species of Aspidisca was far greater than those of closely related genera. The ITS1-5.8S-ITS2 coding regions and partial histone H4 genes of six morphospecies in the Diophrys-complex were sequenced along with their SSrRNA genes and used to compare phylogenies constructed from single data sets to those constructed from combined sets. Results indicated that combined analyses could be used to construct more reliable, less ambiguous phylogenies of complex groups like the order Euplotida, because they provide a greater amount and diversity of information.     

Evolution of discocephalid ciliates: Molecular,morphological and ontogenetic data support a sister group of discocephalids and pseudoamphisiellids (Protozoa,Ciliophora) with establishment of a new suborder Pseudoamphisiellina subord. n.

Discocephalids and pseudoamphisiellids are possibly two of the most confused groups among hypotrichous/euplotid ciliates regarding their systematic position and phylogenetic relationships. The former were often regarded as related to euplotids while the latter, in the absence of molecular data, were mostly assigned to the urostylid-like hypotrichs. In the present work, the small subunit rRNA genes of several rarely observed discocephalid and pseudoamphisiellid genera were analyzed to obtain insights into the phylogenetic relationships of these highly ambiguous Spirotrichea. Four different tree reconstruction algorithms yielded nearly identical topologies, which indicated both groups belong to the same assemblage. This assemblage is clearly isolated as a deep-branching clade and invariably positioned between Euplotida and Hypotricha. The sister group relationship of the Pseudoamphisiellidae and Discocephalidae supports the previous suggestion that they might represent an ordinal taxon, the Discocephalida. Both morphological and morphogenetic features indicate that the pseudoamphisiellids should be placed in the order Discocephalida but as a sister group to other typical discocephalids. Thus we propose establishing a new suborder, Pseudoamphisiellina subord. n. The new taxon is diagnosed by the following characteristics: (i) two distantly separated midventral rows that are morphogenetically formed with an urostylid mode; (ii) absence of the “frontoterminal row”, which is formed from the posterior-most frontoventral-transverse cirral anlage in all other typical urostylids; (iii) numerous caudal cirri that derive from each of the dorsal kinety anlagen; (iv) right marginal row that has a unique de novo origin; and (v) inhabiting periphytic communities. The validity of the suborder Pseudoamphisiellina is firmly supported by molecular data.     

Phylogenetic position of the marine ciliate, Certesia quadrinucleata (Ciliophora; Hypotrichia; Hypotrichida) inferred from the complete small subunit ribosomal RNA gene sequence

The complete small subunit rRNA (SSrRNA) gene sequence of the rare marine hypotrich, Certesia quadrinucleata Fabre-Domergue, 1885, was determined, and found to be 1752 nucleotides long. The phylogenetic position of this species was deduced using distance matrix, maximum parsimony and maximum likelihood methods. Certesia was consistently demonstrated to be a member of the Aspidisca-Euplotes group and clearly exhibits a very close relationship to the well-known genus Euplotes (99% Bay, 99% LS, 99% NJ, 99% MP). The phylogenetic trees further suggest that: (1) Uronychia and Diophrys, traditionally placed in the family Uronychiidae, branch earlier and share a closer relationship to each other than to other hypotrichs; (2) taxa in Gastrocirrhidae, represented by Euplotidium arenarium, might be an "ancestral" group among "traditional" hypotrichs.     

A molecular approach to arthrotardigrade phylogeny (Heterotardigrada,Tardigrada)

The marine order Arthrotardigrada (class Heterotardigrada, phylum Tardigrada) is known for its conspicuously high morphological diversity and has been traditionally recognized as the most ancestral group within the phylum. Despite its potential importance in understanding the evolution of the phylum, the phylogenetic relationships of Arthrotardigrada have not been clarified. This study conducted molecular phylogenetic analyses of the order encompassing all families except Neoarctidae using nuclear 18S and 28S rRNA fragments. Data from two rare families, Coronarctidae and Renaudarctidae, were included for the first time. The analyses confirmed the monophyly of Heterotardigrada and inferred Coronarctidae as the sister group to all other heterotardigrade taxa. Furthermore, the results support a monophyletic Renaudarctidae + Stygarctidae clade, which has been previously suggested on morphology. Our data indicated that two subfamilies currently placed in Halechiniscidae are only distantly related to this family. We propose that these taxa are each elevated to family level (Styraconyxidae (new rank) and Tanarctidae (new rank)). The morphology of tardigrades is discussed in the context of the inferred phylogeny.     

A phylogeny of the families of fossil and extant tetraodontiform fishes (Acanthomorpha, Tetraodontiformes), Upper Cretaceous to Recent

A data matrix is presented of 210 morphological characters (mostly osteological, some external) for 20 extant taxa of the ten Recent families of tetraodontiform fishes and 36 fossil tetraodontiforms. The oldest of these are from the Upper Cretaceous (95 Mya); most are from the Lower to Middle Eocene (50–58 Mya). There are two outgroup taxa (a zeiform and a caproid). A cladistic analysis of this matrix for only the extant taxa produced two equally parsimonious trees that call into question the monophyly of some of the previously accepted major higher-level tetraodontiform clades. Inclusion in the analysis of the large number of available fossil taxa helps to resolve relationships between family level clades. The new phylogenetic hypothesis, together with stratigraphic and biogeographical data, is used to discuss scenarios of the origin and evolution of the major clades of the order.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 565−617.     

First molecular evidence for reassessing phylogenetic affinities between genets (Genetta) and the enigmatic genet-like taxa Osbornictis, Poiana and Prionodon (Carnivora, Viverridae)

Gaubert, P., Tranier, M., Delmas, A.-S., Colyn, M. & Veron, G. (2004). First molecular evidence for reassessing phylogenetic affinities between genets ( Genetta ) and the enigmatic genet-like taxa Osbornictis , Poiana and Prionodon (Carnivora, Viverridae). — Zoologica Scripta, 33 , 117–129.
The subfamily Viverrinae is a composite group of carnivores comprising the large and plantigrade terrestrial civets ( Civettictis , Viverricula and Viverra ) and the slender and generally more arboreal genets and genet-like taxa ( Genetta , Prionodon , Poiana , Osbornictis ), both having Asiatic and African representatives. The problematic phylogenetic relationships between genets and genet-like taxa are addressed for the first time from a molecular perspective through complete cytochrome b gene sequences. We used a large taxonomic sample set including some very rare and crucial species such as Osbornictis piscivora , Poiana richardsonii (museum specimen material) and Genetta johnstoni . The results from parsimony, distance and maximum likelihood analyses do not support the monophyly of the Viverrinae and contradict previous morphological hypotheses. The Asiatic linsangs ( Prionodon spp.) are excluded from the Viverrinae and represent either a basal Feliformia or Viverridae. The other genet-like taxa constitute a strongly supported monophyletic African group, in which the African linsang (represented by Poiana richardsonii ) is a sister group to the genets. The aquatic genet Osbornictis piscivora is included within the latter clade, and the genus Osbornictis should be considered a junior synonym of Genetta . African and Asiatic terrestrial civets are monophyletic, but their phylogenetic affinities with the genet-like clade are inconclusive using our data set. On the basis of our molecular results, morphological convergences and adaptations to peculiar habitats and ways of life within genets and genet-like taxa are discussed.     

A review of iguanian and anguimorph lizard genitalia (Squamata: Chamaeleonidae; Varanoidea, Shinisauridae, Xenosauridae, Anguidae) and their phylogenetic significance: comparisons with molecular data sets

We compare phylogenetic hypotheses for iguanian (chameleonids) and anguimorph lizard groups (varanoids, xenosauroids, anguids) which were generated from analyses of genital (hemipenial) morphology, with recent molecular phylogenetic approaches towards the same groups. Taxa with infraspecific communication by means of visible, sexually dimorphic epigamic characters usually have less diverse genital structures than taxa with less developed visible epigamic characters but with a more highly developed chemical intersexual communication. Generally, it turned out in the cases considered here, that phylogenetic hypotheses based on hemipenial characters coincide much better with molecular-genetic phylogenies than with earlier concepts based solely on external morphology. It seems that genital morphological characters are phylogenetically more informative – on both the species and the supraspecific level – than external morphological characters at least in these examples, because the former seem not to be affected by environmental selective pressures but seem to be only subject to sexual selection. Our data suggest that sexual selective pressure on genital structural diversity is higher the less sexually dimorphic, optical cues for infraspecific communication have evolved. They further suggest a correlation with the mating system (single versus multiple matings).     

Morphological,Ultrastructural, and Molecular Characterization of Euplotidium rosati n. sp. (Ciliophora,Euplotida) from Guam

We combined morphological (i.e. live, stained, scanning, and transmission electron microscopy) with morphometric and molecular analysis to describe a ciliate species collected from shallow reefs in Guam, grown, and maintained in our laboratory. The species was recognized as a member of Euplotidium, and compared with established species of the genus: Euplotidium itoi Ito 1958; Euplotidium psammophilus (Vacelet 1961) Borror 1972; Euplotidium arenarium Magagnini and Nobili 1964; Euplotidium helgae Hartwig 1980; Euplotidium prosaltans Tuffrau 1985, and Euplotidium smalli Lei, Choi and Xu, 2002. To obtain more elements to compare the species, new morphometric data and additional SSU rRNA gene sequences of E. itoi and of E. arenarium are reported. On the basis of this comparison, we established the new species Euplotidium rosati that has a cirral pattern composed of 12 frontoventral and six transverse cirri, and lacks the left marginal cirrus. Euplotidium rosati harbors on its dorsal surface epixenosomes, the peculiar extrusive symbionts described in other Euplotidium species. The whole body of our observations together with the analysis of the data available in the literature leads us to propose a redefinition of the genus. The results may also be useful to clarify the tangled relationship between Euplotidium and Gastrocirrhus.     

Morphological and Molecular Redefinition of Euplotes platystoma Dragesco & Dragesco‐Kernéis, 1986 and Aspidisca lynceus (Müller,1773) Ehrenberg, 1859, with Reconsideration of a “Well‐known” Euplotes Ciliate,Euplotes harpa Stein, 1859 (Ciliophora,Euplotida)

We documented the morphology, infraciliature, silverline system, and molecular data of two euplotid species isolated from China, including two populations of the poorly known Euplotes platystoma Dragesco & Dragesco‐Kernéis, 1986 and the previously well described Aspidisca lynceus (Müller, 1773 ) Ehrenberg, 1830. Based on the information available, an improved diagnosis of Euplotes platystoma is given, including: a narrow adoral zone with 44–68 membranelles, 10 frontoventral, 5 transverse, 2 left marginal and 2 caudal cirri, 11–13 dorsal kineties with 17–25 dikinetids in the mid‐dorsal row, and dorsal silverline system of the double‐eurystomus type. The Chinese population of Aspidisca lynceus closely resembles previously described populations. Phylogenetic analyses inferred from SSU rDNA sequences show that E. platystoma is closely related with E. neapolitanus, and the internal position of A. lynceus within this genus is still not robust. A reconsideration of the “well‐known” Euplotes harpa and a comparison of all SSU rDNA sequences of E. harpa in GenBank are provided. We speculate that the sequences available from GenBank under the name of E. harpa are very likely from misidentified materials, that is, the identity of the species currently associated with the SSU rDNA of this “well‐known” form in molecular databases requires further confirmation.     

A molecular phylogeny of Planorboidea (Gastropoda, Pulmonata): insights from enhanced taxon sampling

Planorbid gastropods are the most diverse group of limnic pulmonates, with both discoidal and highspired taxa. Phylogenetic relationships among these genera are confused and controversial. In particular, the monophyly of the limpet‐like taxa (traditionally Ancylidae) is disputed. Even recent molecular studies have concluded that substantially more work is necessary to solve the remaining issues concerning intergeneric phylogenetic relationships and higher taxa systematics. Planorbid snails are of great significance for humans as several members of this group are intermediate hosts of blood flukes (schistosomes) causing a chronic disease, schistosomiasis. We used the two independent molecular markers COI and 18S (concatenated dataset of 2837 nucleotide bp) to infer phylogenetic relationships of 26 genera (27 species) of Planorboidea, represented mostly by type species from mainly topotypical populations. With the majority of the taxa discussed not having been studied previously, this study attempted to test several hypotheses on planorbid phylogenetic relationships using Bayesian inference techniques. The monophyly of Planorboidea (= ‘Ancyloplanorbidae’) is strongly suggested on the basis of our extensive molecular analysis. Besides a distinct Burnupia clade, two major clades were recovered that correspond to family level taxa (traditional Bulinidae and Planorbidae). Considerable rearrangements of suprageneric taxa are evident from the phylogeny inferred. Therefore, the only clades recognized by current classifications and supported by our analysis are Planorbini and Segmentinini. The present study found that Ancylidae as traditionally understood, i.e. covering most freshwater limpet gastropods, is paraphyletic, as the genera of Burnupia and Protancylus have been shown to lie phylogenetically outside the Ancylini. Chromosome numbers and levels of polyploidy are discussed in the light of the new phylogeny. An earlier theory of shell shape evolution, i.e. that of patelliform taxa being most advanced, was not supported by this study; a limpet‐shaped taxon is most basal within Planorboidea. Although many taxa still remain to be studied, our results will hopefully contribute towards a better understanding of this very important group of freshwater organisms. Some taxonomic implications are discussed.     

The evolutionary radiation of modern birds (Neornithes): reconciling molecules, morphology and the fossil record

The pattern, timing and extent of the evolutionary radiation of anatomically modern birds (Neornithes) remains contentious: dramatically different timescales for this major event in vertebrate evolution have been recovered by the 'clock-like' modelling of molecular sequence data and from evidence extracted from the known fossil record. Because current synthesis would lead us to believe that fossil and nonfossil evidence conflict with regard to the neornithine timescale, especially at its base, it is high time that available data are reconciled to determine more exactly the evolutionary radiation of modern birds. In this review we highlight current understanding of the early fossil history of Neornithes in conjunction with available phylogenetic resolution for the major extant clades, as well as recent advancements in genetic methods that have constrained time estimates for major evolutionary divergences. Although the use of molecular approaches for timing the radiation of Neornithes is emphasized, the tenet of this review remains the fossil record of the major neornithine subdivisions and better-preserved taxa. Fossils allowing clear phylogenetic constraint of taxa are central to future work in the production of accurate molecular calibrations of the neornithine evolutionary timescale.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 141 , 153–177.     

A morphometric and molecular study in Tortula subulata complex (Pottiaceae, Bryophyta)

Specimens belonging to Tortula subulata complex ( T. inermis , T. mucronifolia and T. subulata ) were analysed using a combination of morphometric methods based on quantitative characters [principal component analysis (PCA), discriminant analysis (DA); 76 samples)] and molecular methods (ITS1 – 5.8S rRNA gene and ITS2; 47 samples) to assess patterns of morphological and molecular differentiation within this complex of taxa. The study shows that four species can be recognized: T. mucronifolia , T. subulata , T. inermis and T. subulata var. angustata with bistratose border, which is elevated to the species rank as T. schimperi nom. nov. The most valuable quantitative characters for identification of these species are the strata number of the marginal laminal cells, the ratio of middle marginal laminal cell width/middle marginal laminal cell length, basal membrane of peristome length, middle laminal cell width and papillae number on the middle laminal cells. The internal transcribed spacer (ITS) data suggest that this group of taxa is not monophyletic, T. mucronifolia being close to Protobryum bryoides (= Tortula protobryoides ). The remaining species seem to be a monophyletic group, T. schimperi being the sister group of the clade composed by T. inermis and T. subulata . T. subulata is considered to be of high morphological variability, for which ITS sequences did not resolve the internal relationships.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 333–350.     

A phylogenetic analysis of the evolution of moult strategies in Western Palearctic warblers (Aves: Sylviidae)

Adult birds replace their flight feathers (moult) at least once per year, either in summer after termination of breeding or (in the case of some long-distance migratory species) in the winter quarters. We reconstructed the evolutionary pathways leading to summer and winter moult using recently published molecular phylogenetic information on the relationships of the Western Palearctic warblers (Aves: Sylviidae). Our phylogenetic analysis indicates that summer moult is the ancestral pattern and that winter moult has evolved 7–10 times in this clade. As taxa increased their migratory distance and colonized northern breeding areas, summer moult disappeared and winter moult evolved. Our data also allows us to trace the historical origins of unusual moult patterns such as the split-moult and biannual moult strategies: the most parsimonous explanations for their origins is that they evolved from ancestral states of summer moult. We briefly discuss our results in the light of recent criticisms against phylogenetic comparative methods and the utility of historical versus functional definitions of adapation.     

Phylogeny of drepanosiphine aphids sensu lato (Hemiptera,Aphidoidea) inferred from molecular and morphological data

As the second largest and most diverse group in the superfamily Aphidoidea, the phylogeny of drepanosiphine aphids sensu lato (s.l.) is critical for discussing the evolution of aphids. However, the taxa composition and phylogenetic relationships of drepanosiphine aphids s.l. have not been fully elucidated to date. In this study, based on total-evidence analyses combining 4 molecular genes (3 mitochondrial, COI, tRNA-Leu/COII, and CytB; 1 nuclear, EF-1ɑ) and 64 morphological and biological characteristics, the phylogeny of this group was reconstructed for the first time at the subfamily level using different datasets, parsimonies and model-based methods. All of our phylogenetic inferences clearly indicated that the drepanosiphine aphids s.l. was not a monophyletic group and seemed to support the division of the drepanosiphine aphids s.l. into different groups classified at the subfamily level. Calaphidinae was also not a monophyletic group, and Saltusaphidinae was nested within this subfamily. Drepanosiphinae was not clustered with Chaitophorinae, which was inconsistent with the previous hypothesis of a close relationship between them, illustrating that their phylogeny remains controversial. Overall, some groups of drepanosiphine aphids s.l., including Phyllaphidinae, Macropodaphidinae, Pterastheniinae, Lizeriinae, Drepanosiphinae, Spicaphidinae, Saltusaphidinae, and Calaphidinae, clustered together and might constitute the actual drepanosiphine aphids s.l. To a certain extent, our results clarified the phylogenetic relationships among drepanosiphine aphids s.l. and confirmed their taxonomic status as subfamilies.     

Genetc divergence and phylogeny of the Salmoninae based on allozyme data

The data on 31–37 allozyme loci in 21 species of nine salmonid genera are used for phylogenetic analysis by seven distance methods and several variants of cladistic analysis. Monophyletic origin for all genera and three sub-families of the Salmonidae is corroborated. The closest phylogenetic relationships are characteristic of Parasalmo and Oncorhynchus (bootstrap support is 88–99%), Brachymystax and Hucho (68–97%), and the clade ( Brachymystax + Hucho )+ Salmo (up to 85%). The patterns of phylogenetic relationships in the group Salmo-Parasalmo-Oncorhynchus are analogous to those in the group Parahucho-Hucho-Brachymystax. The position of Parahucho in phylogenetic trees of the Salmoninae is extremely unstable, although it is most likely associated with the clade ( Brachymystax + Hucho)+Salmo ) or Salvelinus. When using the out group analysis, Salvelinus appears as the earliest branch of the Salmoninae tree, whereas if the molecular clock is assumed, the basal position is occupied by Oncorhynchus. However, the latter genus is probably characterized by a substantially increased rate of molecular evolution.