Phylogenetic Scheme Research Articles

Characterization of the West Siberian lineage of zokors (Mammalia, Rodentia, Spalacidae, Myospalacinae) and divergence in molar development

AbstractZokors (Myospalacinae) continue to be the center of systematics discussions. Phylogenetic schemes based on molecular data do not always agree with each other, nor can phylogenetic schemes based on paleontological material be complete due to the only-partial description of West Siberian zokors. This paper tries to fill this gap and presents a description of the West Siberian lineage from the late early Pleistocene to the present, together with an analysis of molar development in other zokor lineages. We describe two new species and one subspecies (Myospalax myospalax krukoveri n. ssp., Myospalax convexus n. sp., Prosiphneus razdoleanensis n. sp.) ancestral to the extant Myospalax myospalax Laxmann, 1769. We also reveal differences in the ontogeny of molars of modern species that were not previously detailed. These differences, together with paleontological data, indicate that in the West Siberian lineage, peramorphosis occurred in the structure of the chewing surface (with the exception of the lower m1), whereas in all other zokor lineages, there was pedomorphosis. On the basis of these results, we suggest a new view on the systematics of Myospalacinae.UUID: http://zoobank.org/b06d6c99-1648-454b-9b95-4d869bfe8bdc

Phylogeny and Biogeography of Morus (Moraceae)

The mulberry genus, Morus L. (Moraceae), has long been taxonomically difficult, and its species circumscription has only been defined recently. This genus comprises ca. 16 species distributed across Asia and the Americas, yet its biogeographic history remains poorly understood. In this study, we reconstructed the phylogeny and explored the biogeographic history of Morus using a combination of newly generated and previously published Hyb-Seq data. Our nuclear phylogeny recovered three well-supported geographic clades of Morus and showed that M. notabilis (China) is sister to the American clade plus the Asian clade. Multiple reticulation events among species of Morus and extensive incomplete lineage sorting (ILS) likely explain the difficulties in inferring phylogenetic relationships within the genus. Divergence time estimation indicated that Morus originated at the Eocene–Oligocene boundary, and current lineages started to diverge during the early Miocene, there is ambiguity surrounding the ancestral area with the two most likely regions being Sino-Himalaya or the Americas. Biogeographic inference and the fossil record suggest that Morus might have experienced extensive local extinction events during the Tertiary. Morus has expanded its distributional range through two dispersals from the Sino-Himalayan and Sino-Japanese regions to Southeast Asia. In summary, our new phylogenetic scheme and the biogeographic history presented here provide an essential foundation for understanding species relationships and the evolutionary history of Morus.

A Phylogenetic Classification of Grusonia, Opuntioideae, Cactaceae

A new classification proposal for the genus Grusonia is discussed and described. Three new sectional names are advanced following a recently published phylogenetic scheme derived from a five-plastid time-calibrated phylogeny. Two subgenera, Corynopuntia and Grusonia, and four sections, Radicaulenta, Xylocaulis, Grusonia and Spinicarpa are recognized, described, and discussed.

Microplate tectonics and environmental factors as distribution drivers in Western Mediterranean freshwater planarians

AbstractAimSpecies biogeography mainly focuses on palaeogeographical events, while environmental factors are generally overlooked despite their importance in species diversification. Here, we use an integrative approach to understand how palaeogeographical and environmental processes shape species distribution and focus on freshwater planarians as the model system.LocationWestern Mediterranean.TaxonDugesia.MethodsWe inferred the phylogenetic relationships of most known Dugesia species in the area using six molecular markers. We then estimated their divergence times and reconstructed their ancestral distribution ranges. We also performed environmental niche modelling analyses using Dugesia subtentaculata as a model to evaluate the effects of several hydro‐environmental variables and the likely existence of interspecific competition on Dugesia distributions.ResultsOur results provide a new phylogenetic scheme for Dugesia from the Western Mediterranean and show that the time splits between the lineages and their putative ancestral distribution ranges are correlated with microplate tectonic dynamics within the region during the Oligocene–Miocene period. Our environmental niche modelling analyses indicate that the type of land cover and the slope of the terrain are the most important abiotic factors driving the distribution of Dugesia from this region. Finally, we found a partial niche overlap between D. subtentaculata and two other common planarian species from the Iberian Peninsula.Main conclusionsThe microplate tectonic dynamics of the Western Mediterranean during the Oligocene–Miocene period, together with the position of the mountain ranges and posterior climate changes, may have played crucial roles in driving the biogeographical history of Dugesia in this region. Moreover, both interspecific competition and changes in fluvial characteristics driven by human activities may affect the current diversity and distribution of Dugesia in the Western Mediterranean. This study highlights the importance of integrating different types of information to study the biogeographical history of a species.

The evolution of hermit crabs (Crustacea, Decapoda, Anomura, Paguroidea) on the basis of carapace morphology: a state-of-the-art-report

In our ongoing studies of both extinct and extant hermit crabs (Paguroidea Latreille, 1802), we have observed and recorded a number of morphological changes that have taken place between Early Jurassic times (c. 185 million years ago) and the present day. Species compositions of paguroid assemblages from marine Upper Jurassic and Lower Cretaceous rocks in Europe are here compared with those of modern marine settings. Basal paguroids with cylindrical carapaces predominated in reefal environments during the Late Jurassic, but were gradually replaced by hermit crabs with non-cylindrical carapaces. The most basal paguroids reveal a branchial groove, but branchial condensation towards a single (i.e., cervical) groove is here shown to have occurred early in their evolutionary history. In several extant, genera remnants of a branchial groove, in combination with several other basal features, can be seen. For this reason, these are here considered to be the most primitive members amongst extant paguroids. In this study, we resurrect the family Probeebeidae and erect a new family, Paguropsidae n. fam, to accommodate extant basal hermit crabs such as Paguropsis Henderson, 1888, Eopaguropsis Fraaije, Krzemiński, Van Bakel, Krzemińska & Jagt, 2012 and Paguropsina Lemaitre, Rahayu & Komai, 2018. Described are also one pair of Early Jurassic (Pliensbachian) and two pairs of Middle Jurassic (Callovian) isochelous paguroid chelae, all collected recently. A new specimen of Schobertella reveals some important morphological traits of the shield that had not been observed previously. The earliest known example to date of clearly heterochelous chelae in the fossil record of hermit crabs originates from upper Kimmeridgian/Tithonian strata in the Boulonnais (northwestern France). For the first time, a phylogenetic scheme of marine Paguroidea, as based on morphological data of carapaces, is presented.

Loricate choanoflagellates (Acanthoecida) from warm water seas. VIII. Crinolina Thomsen and Diaphanoeca Ellis

The loricate choanoflagellate genera Diaphanoeca Ellis and Crinolina Thomsen encompass a total of ten species. The majority of these are recorded from the warm water regions reported on here. A distinct morphological dichotomy characterizes the genus Diaphanoeca as currently circumscribed. The species distribute themselves within a ‘D. grandis subgroup’ and a ‘D. pedicellata subgroup’ distinguished on e.g., the position of the protoplast inside the lorica chamber and the elaboration of the anterior projections. We are, while awaiting in particular further molecular evidence, taking a conservative approach and abstain from dealing with the subgroup issue at the generic level. The examination of material from the warm water regions of the world’s oceans has resulted in the description of D. sargassoensis sp.n., D. pseudoundulata sp.n., and D. throndsenii sp.n., and a thorough re-examination of D. undulata. Species of Crinolina share multiple features with in particular the D. grandis species subgroup. It is yet relevant, both in a morphological and molecular perspective, to retain the genus Crinolina which remains unambiguously defined based on the posteriorly open lorica. A high level of agreement is found when contrasting morphological and molecular based phylogenetic schemes.

A new species of Omphalocyclus Bronn, O. omanensis sp. nov., from the upper Campanian of Oman: Phylogenetic and stratigraphic implications

The genus Omphalocyclus Bronn is a Late Cretaceous orbitoidal larger foraminifera, usually considered as a marker for the Maastrichtian. Herein we describe Omphalocyclus specimens from the upper part of the Qahlah Formation in North Oman, probably representing the most primitive developmental stage of the genus in the Tethys. The studied specimens are characterized by having delicate discoidal, biconcave tests with a notably small, ‘trilocular’ embryonic apparatus and a few (usually 2) epi-embryonic chamberlets. The embryonic wall in some specimens is thin and hardly discernible as a separate morphological entity compared to following chamberlets. Duplication of the annular series of chamberlets in the equatorial plane (equatorial layer), a characteristic morphological feature of the genus, is observed at a late ontogenetic stage. After comparison of these specimens with specimens of type-species O. macroporus (Lamarck) from the Simsima Formation in Oman and previously described species (e.g., O. anatoliensis Özcan, O. cideensis Özcan, O. maldonensis Gunter, Robinson, Mitchell), a new species, O. omanensis sp. nov. is established. The stratigraphic distribution of the genus is updated, and a tentative phylogenetic scheme is proposed. The upper part of the Qahlah Formation in the Buraymi region is assigned to the upper Campanian based on the recognition of calcareous nannofossils Zones CC22b and CC23a and the occurrence of Orbitoides medius (d’Archiac).

Philosophy of Evolutionary Biology

Cognition is not a process of mastering truths, i.e., grains of ultimate knowledge. Even in the details, cognition only allows us to get closer to the ultimate truth, not to reach it. Consequently, the real tool of knowledge is not a proof, but a presumption. The latter refers to a certain decision that was successfully established in the past in an appropriate context and therefore can be taken without additional proofs, though only in the absence of serious contradictory evidence. Two paradigms compete within the framework of modern evolutionary biology, i.e., the dominant cladistic paradigm and the often disregarded but indestructible phyletic paradigm, which grew from the traditional view on systematics and evolution. Cladistics corresponds to the genetic (=population-genetic, “synthetic”) theory of evolution, whereas phyletics corresponds to the holistic (=“epigenetic”) one. The cladistic paradigm seemingly offers a strict procedure of objective analysis, but its prerequisites, such as the mandatory dichotomy of a particular phylum combined with the simultaneous disappearance of an ancestor, which disregards the possibility of speciation without divergence, are hardly consistent with the real order of things, and unavoidable sources of subjectivity are also usually ignored. The holistic paradigm does not represent a less clear procedure, but a more complex protocol of analysis, since it not only recognizes the unavoidable elements of subjectivity but also explicitly introduces them into the research protocol as a choice between the conflicting presumptions. Phyletics, as part of the holistic paradigm, provides taxonomic and phylogenetic schemes that are stabler in the long run, and the holistic theory of evolution, together with the adaptive compromise metaphor derived from it, can explain many evolutionary phenomena that are incompatible with the genetic (“synthetic”) theory of evolution, such as the discrete nature of biological diversity, the fundamental nonuniformity of the evolutionary process, and the paradox of the inverse correlation between the evolutionary rate and level of organization, e.g., the highest and lowest rates of the evolution of large mammals and microorganisms, respectively.

Antimicrobial resistance patterns and phylogenetic analysis of Shiga toxin-producing Escherichia coli strains from goats using both Clermont phylogenetic schemes

Foodborne transmission of Shiga toxin-producing Escherichia coli (STEC) poses a threat to public health. The Clermont typing schemes (previous and revised) have been used widely to phylotype E. coli. The present study was conducted to compare the relationship of the Clermont phylogenet-ic schemes in STEC strains isolated from goats and antibiotic resistance patterns in the southeast of Iran. Overall 52 strains carrying the stx gene were used for subsequent analysis. All strains were determined by analysing the genomic DNA with a PCR-based method using the two Clermont et al. (2000, 2013) schemes. Extended spectrum beta-lactamase (ESBL) producing strains were con-firmed by the double disk-diffusion method. STEC strains were also tested for susceptibility to 20 antimicrobials agents. In the original Clermont method, the prevalent phylogroups were B1 (69.2%) and A (28.8%). The significant phylogenetic groups of strains according to the revised Clermont method were B1 (82.7%), A (13.5%) and unknown (3.8%). However, STEC strains underwent changes as noted from A to B1 (17.3%), B1 to unknown (3.8%), B1 to A (1.9%) and D to B1 (1.9%) groupings. Of the 52 stx-positive strains, two ESBL producing strains were detected. Susceptibility data showed that the most frequent resistance phenotype was related to cefazolin (90.4%), streptomycin (88.5%), ampicillin (86.5%) and oxytetracycline (82.7%) respectively. Alt-hough the overall frequency of the reassigned phylotypes was not significant, most changes oc-curred within the A phylotype. Therefore, implementation of the new method on isolates belong-ing to the A phylotype in the old method seems to be necessary to obtain accurate results.

Otolith Morphology and Relationships of Several Fish Species of the Suborder Scorpaenoidei

Otolith (sagitta) morphology is described in six tropical fish species belonged to different genera of the suborder Scorpaenoidei: Synanceia horrida, Inimicus sinensis, Parascorpaena picta, Sebastapistes cyanostigma, Scorpaenopsis papuensis, and Dendrochirus zebra. Based on otolith shape (six shape indices and elliptic Fourier analysis), S. horrida is similar to Sc. papuensis and I. sinensis is similar to D. zebra. A comparison of otolith shape in P. picta, D. zebra, and three species of the family Sebastidae (Helicolenus dactylopterus, Sebastes semicinctus, and S. hopkinsi) using elliptic Fourier and principal component analyses shows that the clusters of H. dactylopterus and S. semicinctus partly overlap with the cluster of D. zebra, and the cluster of S. hopkinsi partly overlaps with the cluster of P. picta. The data on otolith shape do not correspond with current phylogenetic schemes that indicates relative independence of the inner ear evolution.

Some Data on Reproductive Biology of Spotted Ghoul Inimicus sinensis (Synanceiidae)

Gonadal structure, cytological condition of oocytes, ultrastructure of egg envelope, and spermatozoa morphology are studied in the individuals of Inimicus sinensis 120–230 mm TL with the gonads mainly at maturity stage IV. The males possess hypertrophied urinary bladders. Based on oocytes’ size distribution in the ovaries, the oogenesis is continuous and the spawning is multiple. Oocytes of the maturation period are 600–700 µm in diameter. The batch fecundity is 15 380 oocytes on average. The zona radiata of oocytes that have completed growth is 10.2 µm in width on average and it consists of two layers. The narrow outermost layer of the egg envelope approximately 0.34 µm width is most likely chorion. Spermatozoon ultrastructure of I. sinensis does not notably differ from that in other representatives of the suborder Scorpaenoidei with external insemination. The centriolar complex is characterized by orthogonal position of centrioles. Based on ovarian structure, the representatives of the genus Inimicus do not differ from the majority of teleost fishes and viviparous species of the genera Sebastes and Sebastiscus. However, many representatives of the suborder Scorpaenoidei have unique ovarian structure with the central ovigerous stroma attached to the anterior part of the ovary. Based on the current phylogenetic schemes, this ovarian type evolved independently in several evolutionary lineages.

New Data on the Bajocian–Bathonian Parkinsoniidae (Ammonoidea, Perisphinctoidea)

Some structural features of the suture line of adult representatives of the family Parkinsoniidae are analyzed. It has been established that in the genera Caumontisphinctes, Pseudocosmoceras, Sokurella and most Rarecostites, the ventral lobe (V) is deeper than the first lateral lobe (U). On the contrary, in the microconchs of the later Rarecostites, as well as in the genera Parkinsonia and Oraniceras, lobe V is smaller than lobe U; in macroconchs they can be of approximately equal depth. Based on data on shell morphogenesis, ornamentation, and the chronostratigraphic succession of taxa, a phylogenetic scheme for the Parkinsoniidae, including Parkinsoniinae Buckman (genera Caumontisphinctes, Rarecostites, Parkinsonia, and Oraniceras), and Pseudocosmoceratinae Sasonov (genera Pseudocosmoceras and Sokurella), is proposed. The assignment of the genus Djanaliparkinsonia to the subfamily Garantianinae (Stephanoceratidae), based on similarity of the sutural outline, is confirmed.

Spermatozoa Morphology of Goatfishes (Mullidae): Upeneus sulphureus

Spermatozoa morphology of sulphur goatfish Upeneus sulphureus is studied by the methods of scanning and transmission electron microscopy. The shapes of spermatozoon heads are compared in U. sulphureus, U. tragula, U. margarethae, and Parupeneus multifasciatus. The U. sulphureus spermatozoon is characterized by the oval head flattened on a side, a nucleus with a deep U-shaped fossa, coaxially located centrioles, and two mitochondrial sections in the midpiece. On the flattened side of the head, its apical end is slightly pointed and bent. Based on the spermatozoon head shape, U. tragula and U. margarethae differ from all representatives of the family Mullidae with described sperm morphology in strongly bent and pointed apical end of the spermatozoon head and a single mitochondrial section in the midpiece. The data on comparative spermatozoa morphology are discussed in connection with current phylogenetic schemes.

Phylogenomic interrogation resolves the backbone of the Pseudoscorpiones tree of life

Pseudoscorpiones, with nearly 3700 described species, are an ancient and globally distributed group of arachnids with a fossil record dating back to the Middle Devonian. Previous attempts to reconstruct their phylogenetic history have used morphology or a few amplicons, mostly of rRNAs and mitochondrial genes, which have not been able to completely resolve family-level relationships nor the earliest nodes in the pseudoscorpion tree—those which are most informative about the origins of key characters like venoms and silk. Here we undertake a phylogenetic approach using 41 pseudoscorpion transcriptomes and a series of analyses that account for many of the common pitfalls faced in large phylogenomic analyses. All analyses, using concatenation methods and coalescent approaches, supported monophyly of Iocheirata (the venomous pseudoscorpions), which diversified mostly during the Mesozoic, but paraphyly of Epiocheirata, with a sister group relationship of Feaelloidea to Iocheirata, with Chthonioidea as their sister group. These three main lineages were established during the mid-to-late Paleozoic. Our phylogenetic scheme is consistent with the prior hypothesis that the lack of venom in Pseudoscorpiones is plesiomorphic and not a synapomorphy of Epiocheirata. Based on the results of this study, a new classification is proposed for Pseudoscorpiones including the following new nomenclatural and taxonomic acts: the new suborders Palaeosphyronida Harvey and Atoposphyronida Harvey for Dracochelidae and Feaelloidea, respectively; the newly recognized superfamily Garypinoidea for Garypinidae and Larcidae; the revised rank for Lechytiidae and Tridenchthoniidae, which are regarded as subfamilies of Chthoniidae; the revised rank for Tridenchthoniini and Verrucadithini which are regarded as tribes of Tridenchthoniinae; and the elevation of Hesperolpiinae as a distinct family, Hesperolpiidae.

A TAXONOMIC REVISION OF FOSSIL FRESHWATER PEARL MUSSELS (BIVALVIA: UNIONOIDA: MARGARITIFERIDAE) FROM PLIOCENE AND PLEISTOCENE DEPOSITS OF SOUTHEASTERN EUROPE

Margaritiferidae is an ancient freshwater bivalve family originated in the Jurassic in East Asia. Here, we revise several nominal taxa of fossil freshwater pearl mussels that were recovered from the Upper Pliocene and Pleistocene deposits of the Dniester and Prut river valleys. Based on morphological and stratigraphic data, we found that these nominal taxa belong to the genus Pseudunio and are junior synonyms of P. flabellatiformis (Grigorowitch-Beresowski, 1915). The new synonymy is proposed as follows: Margaritifera (Pseudunio) moldavica Chepalyga, 1964 syn. nov., Margaritifera (Pseudunio) robusta robusta Chepalyga, 1964 syn. nov., Margaritifera (Pseudunio) robusta speensis Chepalyga, 1964 syn. nov., and Margaritifera (Pseudunio) robusta tirassica Chepalyga, 1964 syn. nov. All these fossil nominal taxa were described based on minor differences in the shell shape and size, hinge structure, and stratigraphic position. Finally, we suggest an updated phylogenetic scheme of the genus Pseudunio, which contains five valid species: P. marocanus (Pallary, 1918) [Eocene – Recent, Morocco], P. auricularius (Spengler, 1793) [Pliocene – Recent, Southern and Western Europe], P. homsensis (Lea, 1865) [Pliocene – Recent, Orontes and Nahr al-Kabir basins], P. flabellatiformis (Grigorowitch-Beresowski, 1915) comb. rev. [Pliocene – Late Pleistocene, paleo-Dniester and paleo-Danube basins, an extinct lineage related to P. auricularius and P. homsensis], and P. flabellatus (Goldfuss, 1837) comb. rev. [Miocene, paleo-Danube Basin, a stem lineage, MRCA of P. auricularius - P. homsensis clade].

Paravian Phylogeny and the Dinosaur-Bird Transition: An Overview

Fil: Agnolin, Federico. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales Bernardino Rivadavia; Argentina. Fundacion de Historia Natural Felix de Azara; Argentina

Internal cranial anatomy of Early Triassic species of \u2020Saurichthys (Actinopterygii: \u2020Saurichthyiformes): implications for the phylogenetic placement of \u2020saurichthyiforms

Background†Saurichthyiformes were a successful group of latest Permian–Middle Jurassic predatory actinopterygian fishes and constituted important, widely-distributed components of Triassic marine and freshwater faunas. Their systematic affinities have long been debated, with †saurichthyiforms often being aligned with chondrosteans, a group today comprising sturgeons and paddlefishes. However, their character-rich endocranial anatomy has not been investigated in detail since the first half of the 20th century. Since then, major advances have occurred in terms of our understanding of early actinopterygian anatomy, as well as techniques for extracting morphological data from fossils.ResultsWe used μCT to study the internal cranial anatomy of two of the stratigraphically oldest representatives of †Saurichthys, from the Early Triassic of East Greenland and Nepal. Our work revealed numerous previously unknown characters (e.g., cryptic oticooccipital fissure; intramural diverticula of braincase; nasobasal canals; lateral cranial canal; fused dermohyal), and permitted the reevalution of features relating to the structure of cranial fossae, basicranial circulation and opercular anatomy of the genus. Critically, we reinterpret the former †saurichthyiform opercle as an expanded subopercle. For comparison, we also produced the first digital models of a braincase and endocast of a sturgeon (A. brevirostrum). New information from these taxa was included in a broad phylogenetic analysis of Actinopterygii. †Saurichthyiforms are resolved as close relatives of †Birgeria, forming a clade that constitutes the immediate sister group of crown actinopterygians. However, these and other divergences near the actinopterygian crown node are weakly supported.ConclusionsOur phylogeny disagrees with the historically prevalent hypothesis favoring the chondrostean affinities of †saurichthyiforms. Previously-proposed synapomorphies uniting the two clades, such as the closure of the oticooccipital fissure, the posterior extension of the parasphenoid, and the absence of an opercular process, are all widespread amongst actinopterygians. Others, like those relating to basicranial circulation, are found to be based on erroneous interpretations. Our work renders the †saurichthyiform character complex adequately understood, and permits detailed comparisons with other stem and crown actinopterygians. Our phylogenetic scheme highlights outstanding questions concerning the affinity of many early actinopterygians, such as the Paleozoic–early Mesozoic deep-bodied forms, which are largely caused by lack of endoskeletal data.

Comparative Analysis of Spermatozoa Morphology in Three Fish Species from the Suborder Scorpaenoidei

The methods of scanning and transmission electron microscopy are used for the investigation of external morphology and ultrastructure of spermatozoa in scorpaenoid fishes Parascorpaena picta, Dendrochirus zebra (Scorpaenidae), and Synanceia horrida (Synanceiidae). Based on the literature data, a comparison with other species of the genera Scorpaena, Sebastapistes, and Scorpaenopsis (Scorpaenidae) is conducted. In the studied species, the spermatozoon consists of the rounded head (its length is slightly smaller than its width), moderately developed midpiece, and flagellum. P. picta differs from the other species in the presence of the widening of the cytoplasmic channel surrounding the initial part of the flagellum, the largest numbers of mitochondrial sections, and the longest flagellum. S. horrida does not differ significantly from the representatives of the family Scorpaenidae. However, based on the contour of the head and midpiece (elliptic Fourier analysis), there is a trend to the separation of S. horrida from P. picta and D. zebra. The data on comparative spermatozoa morphology are discussed in relation to current phylogenetic schemes.

Combined phylogenetic analysis of the subclass Marchantiidae (Marchantiophyta): towards a robustly diagnosed classification.

The most extensive combined phylogenetic analyses of the subclass Marchantiidae yet undertaken was conducted on the basis of morphological and molecular data. The morphological data comprised 126 characters and 56 species. Taxonomic sampling included 35 ingroup species with all genera and orders of Marchantiidae sampled, and 21 outgroup species with two genera of Blasiidae (Marchantiopsida), 15 species of Jungermanniopsida (the three subclasses represented) and the three genera of Haplomitriopsida. Takakia ceratophylla (Bryophyta) was employed to root the trees. Character sampling involved 92 gametophytic and 34 sporophytic traits, supplemented with ten continuous characters. Molecular data included 11 molecular markers: one nuclear ribosomal (26S), three mitochondrial genes (nad1, nad5, rps3) and seven chloroplast regions (atpB, psbT-psbH, rbcL, ITS, rpoC1, rps4, psbA). Searches were performed under extended implied weighting, weighting the character blocks against the average homoplasy. Clade stability was assessed across three additional weighting schemes (implied weighting corrected for missing entries, standard implied weighting and equal weighting) in three datasets (molecular, morphological and combined). The contribution from different biological phases regarding node recovery and diagnosis was evaluated. Our results agree with many of the previous studies but cast doubt on some relationships, mainly at the family and interfamily level. The combined analyses underlined the fact that, by combining data, taxonomic enhancements could be achieved regarding taxon delimitation and quality of diagnosis. Support values for many clades of previous molecular studies were improved by the addition of morphological data. The long-held assumption that morphology may render spurious or low-quality results in this taxonomic group is challenged. The morphological trends previously proposed are re-evaluated in light of the new phylogenetic scheme.

Fish growth hormone genes: Divergence of coding sequences in salmonid fishes

Comparison of coding nucleotide sequences of the paralogous GH1 and GH2 genes, as well as of the growth hormone amino acid sequences, in the species of closely related salmonid genera Salvelinus, Oncorhynchus, and Salmo was performed. It was demonstrated that, in different groups of salmonids, the amino acid substitution rates were considerably different. In some cases, an obvious discrepancy between the divergence of growth hormone genes and phylogenetic schemes based on other methods and approaches was revealed. These findings suggest that the reason may be multidirectional selection at duplicated genes at different stages of evolution.