Living and fossil placentals

2004 ◽  
Author(s):  
T.S. Kemp
Keyword(s):  
Sequence Data ◽  
Sister Group ◽  
Morphological Characters ◽  
Molecular Data ◽  
Molecular Sequence Data ◽  
Minor Characters ◽  
Molecular Sequence ◽  
Large Sets ◽  
Anterior Teeth ◽  
Basal Group

The vast majority of living and fossil mammals are placentals. Today there are about 4,400 species, which are traditionally organised into 18 Orders, with an extra one if the Pinnipedia are separated from the Carnivora, and a twentieth if the recently extinct Malagasy order Bibymalagasia is recognised as such. There have been many attempts to discover supraordinal groupings from amongst these Orders based on morphological characters, though few proposals have been universally accepted. It is only with the advent of increasingly large sets of molecular sequence data in the last few years that a reasonably robust resolution looks imminent, although these contemporary analyses are remarkably and controversially at odds with the traditional ones. Novacek et al. (1988) summarised the then current situation regarding supraordinal classification of placentals, a time at which morphology was still dominant but molecular data was at the threshold of significance. They accepted a basal group Edentata that combined the Xenarthra of the New World with the Pholidota of the Old, based on a few cranial characters, loss of the anterior teeth, and reduction of the enamel of the remaining ones. This left the rest of the living placentals as a monophyletic group Epitheria, sharing such apparently minor characters as the shape of the stapes bone in the ear. They found very little resolution within the Epitheria, and concluded that there was a polychotomy of no less than nine lineages arranged as a ‘star’ phylogeny. No remnant of the previously recognised taxon Ferungulata, created by Simpson (1945) for the Carnivora plus the ungulate orders Artiodactyla, Perissodactyla, Proboscidea, Hyracoidea, Sirenia, and Tubulidentata remained. On the other hand, three supra ordinal taxa of earlier authors did survive. One was Gregory’s (1910) Archonta, consisting of generally conservative forms and by now composed of the Primates, Dermoptera, Scandentia, and Chiroptera, but excluding the Lipotyphla. The second was Glires, originating with Linnaeus (1758) and widely accepted ever since, for the Rodentia and Lagomorpha; Novacek et al. (1988) tentatively placed the Macroscelidea as the sister-group of the Glires. The third supraordinal taxon recognised was, like Glires, well-established if not universally accepted.

scholarly journals Investigating the Bivalve Tree of Life – an exemplar-based approach combining molecular and novel morphological characters

2014 ◽  
Vol 28 (1) ◽  
pp. 32 ◽  
Author(s):  
Rüdiger Bieler ◽  
Paula M. Mikkelsen ◽  
Timothy M. Collins ◽  
Emily A. Glover ◽  
Vanessa L. González ◽  
...  
Keyword(s):  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Analytical Framework ◽  
Morphological Characters ◽  
Molecular Data ◽  
Probabilistic Methods ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
Protein Encoding ◽  
Encoding Genes

To re-evaluate the relationships of the major bivalve lineages, we amassed detailed morpho-anatomical, ultrastructural and molecular sequence data for a targeted selection of exemplar bivalves spanning the phylogenetic diversity of the class. We included molecular data for 103 bivalve species (up to five markers) and also analysed a subset of taxa with four additional nuclear protein-encoding genes. Novel as well as historically employed morphological characters were explored, and we systematically disassembled widely used descriptors such as gill and stomach ‘types’. Phylogenetic analyses, conducted using parsimony direct optimisation and probabilistic methods on static alignments (maximum likelihood and Bayesian inference) of the molecular data, both alone and in combination with morphological characters, offer a robust test of bivalve relationships. A calibrated phylogeny also provided insights into the tempo of bivalve evolution. Finally, an analysis of the informativeness of morphological characters showed that sperm ultrastructure characters are among the best morphological features to diagnose bivalve clades, followed by characters of the shell, including its microstructure. Our study found support for monophyly of most broadly recognised higher bivalve taxa, although support was not uniform for Protobranchia. However, monophyly of the bivalves with protobranchiate gills was the best-supported hypothesis with incremental morphological and/or molecular sequence data. Autobranchia, Pteriomorphia, Heteroconchia, Palaeoheterodonta, Archiheterodonta, Euheterodonta, Anomalodesmata and Imparidentia new clade ( = Euheterodonta excluding Anomalodesmata) were recovered across analyses, irrespective of data treatment or analytical framework. Another clade supported by our analyses but not formally recognised in the literature includes Palaeoheterodonta and Archiheterodonta, which emerged under multiple analytical conditions. The origin and diversification of each of these major clades is Cambrian or Ordovician, except for Archiheterodonta, which diverged from Palaeoheterodonta during the Cambrian, but diversified during the Mesozoic. Although the radiation of some lineages was shifted towards the Palaeozoic (Pteriomorphia, Anomalodesmata), or presented a gap between origin and diversification (Archiheterodonta, Unionida), Imparidentia showed steady diversification through the Palaeozoic and Mesozoic. Finally, a classification system with six major monophyletic lineages is proposed to comprise modern Bivalvia: Protobranchia, Pteriomorphia, Palaeoheterodonta, Archiheterodonta, Anomalodesmata and Imparidentia.

The Phylogeny of Rhizocephalan Parasites of the Genus Heterosaccus using Molecular and Larval Data (Cirripedia: Rhizocephala; Sacculinidae)

2008 ◽  
Vol 54 (2) ◽  
pp. 223-238 ◽  
Author(s):  
Henrik Glenner ◽  
Philip Francis Thomsen ◽  
Alexey V. Rybakov ◽  
Bella S. Galil ◽  
Jens T. Hoeg
Keyword(s):  
Sequence Data ◽  
Morphological Characters ◽  
Molecular Data ◽  
Sem Analysis ◽  
Accurate Identification ◽  
Generic Level ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
The Third ◽  
The Family

Within parasitic barnacles of the family Sacculinidae, the genus Heterosaccus is the third largest, with 12 species infesting various brachyuran hosts throughout the world. As part of an effort to reconstruct rhizocephalan phylogeny we performed an analysis of four species of Heterosaccus and of selected sacculinid and non-sacculinid rhizocephalans. We used both molecular sequence data (16s rDNA and 18s rDNA) and morphological characters from an SEM analysis of the cypris larvae. Using Bayesian methods we obtained a highly supported tree in which the four species of Heterosaccus form a monophylum, whereas both the genus Sacculina and the family Sacculinidae are polyphyletic. The sistergroup to Heterosaccus is a clade consisting of the sacculinids Loxothylacus panopaei and the "classical" rhizocephalan Sacculina carcini. The molecular results found support in cypris morphology, where we identified two distinct synapomorphies for Heterosaccus, both present in male cyprids only: A large flap extending posteriorly from the third antennular segment, and the male-specific aesthetasc on the third segment being reduced to a rudiment or lacking completely. Female cyprids didn't show generic level apomorphies but resembled those of other sacculinid species. No morphological synapomorphies were identified between Heterosaccus, L. panopaei and S. carcini. While larval characters proved to be informative, we conclude that future studies on rhizocephalan taxonomy must rely primarily on molecular data, both to provide an overall phylogenetic framework and to assure an accurate identification of species for biogeographical and other biological purposes.

scholarly journals Inferring the deep past from molecular data

2021 ◽  
Author(s):  
Tom A Williams ◽  
Dominik Schrempf ◽  
Gergely J Szöllősi ◽  
Cymon J Cox ◽  
Peter G Foster ◽  
...  
Keyword(s):  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Sister Group ◽  
Molecular Data ◽  
Sister Group Relationship ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
Phylogenetic Methods ◽  
Alternative Hypotheses ◽  
Correct Tree

Abstract There is an expectation that analyses of molecular sequences might be able to distinguish between alternative hypotheses for ancient relationships, but the phylogenetic methods used and types of data analyzed are of critical importance in any attempt to recover historical signal. Here we discuss some common issues that can influence the topology of trees obtained when using overly-simple models to analyze molecular data that often display complicated patterns of sequence heterogeneity. To illustrate our discussion, we have used three examples of inferred relationships which have changed radically as models and methods of analysis have improved. In two of these examples, the sister-group relationship between thermophilic Thermus and mesophilic Deinococcus, and the position of long-branch Microsporidia among eukaryotes, we show that recovering what is now generally considered to be the correct tree is critically dependent on the fit between model and data. In the third example, the position of eukaryotes in the tree of life, the hypothesis that is currently supported by the best available methods is fundamentally different from the classical view of relationships between major cellular domains. Since heterogeneity appears to be pervasive and varied among all molecular sequence data, and even the best available models can still struggle to deal with some problems, the issues we discuss are generally relevant to phylogenetic analyses. It remains essential to maintain a critical attitude to all trees as hypotheses of relationship that may change with more data and better methods.

The status of Myriangiaceae (Dothideomycetes)

Phytotaxa ◽  
2014 ◽  
Vol 176 (1) ◽  
pp. 219 ◽  
Author(s):  
ASHA J. DISSANAYAKE ◽  
RUVISHIKA S. JAYAWARDENA ◽  
SARANYAPHAT BOONMEE ◽  
KASUN M. THAMBUGALA ◽  
QING TIAN ◽  
...  
Keyword(s):  
Sequence Data ◽  
Molecular Data ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
The Family ◽  
The Status ◽  
Sexual State ◽  
Morphological And Molecular Data ◽  
Asexual State ◽  
Molecular Characters

The family Myriangiaceae is relatively poorly known amongst the Dothideomycetes and includes genera which are saprobic, epiphytic and parasitic on the bark, leaves and branches of various plants. The family has not undergone any recent revision, however, molecular data has shown it to be a well-resolved family closely linked to Elsinoaceae in Myriangiales. Both morphological and molecular characters indicate that Elsinoaceae differs from Myriangiaceae. In Elsinoaceae, small numbers of asci form in locules in light coloured pseudostromata, which form typical scab-like blemishes on leaf or fruit surfaces. The coelomycetous, “Sphaceloma”-like asexual state of Elsinoaceae, form more frequently than the sexual state; conidiogenesis is phialidic and conidia are 1-celled and hyaline. In Myriangiaceae, locules with single asci are scattered in a superficial, coriaceous to sub-carbonaceous, black ascostromata and do not form scab-like blemishes. No asexual state is known. In this study, we revisit the family Myriangiaceae, and accept ten genera, providing descriptions and discussion on the generic types of Anhellia, Ascostratum, Butleria, Dictyocyclus, Diplotheca, Eurytheca, Hemimyriangium, Micularia, Myriangium and Zukaliopsis. The genera of Myriangiaceae are compared and contrasted. Myriangium duriaei is the type species of the family, while Diplotheca is similar and may possibly be congeneric. The placement of Anhellia in Myriangiaceae is supported by morphological and molecular data. Because of similarities with Myriangium, Ascostratum (A. insigne), Butleria (B. inaghatahani), Dictyocyclus (D. hydrangea), Eurytheca (E. trinitensis), Hemimyriangium (H. betulae), Micularia (M. merremiae) and Zukaliopsis (Z. amazonica) are placed in Myriangiaceae. Molecular sequence data from fresh collections is required to confirm the relationships and placement of the genera in this family.

A widespread distribution for Arostrilepis tenuicirrosa (Eucestoda: Hymenolepididae) in Myodes voles (Cricetidae: Arvicolinae) from the Palearctic based on molecular and morphological evidence: historical and biogeographic implications

2013 ◽  
Vol 58 (4) ◽  
Author(s):  
Kurt Galbreath ◽  
Kristina Ragaliauskaite ◽  
Leonas Kontrimavichus ◽  
Arseny Makarikov ◽  
Eric Hoberg
Keyword(s):  
Sequence Data ◽  
Molecular Data ◽  
Intraspecific Diversity ◽  
Myodes Glareolus ◽  
Morphological Evidence ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
Biogeographic History ◽  
Mitochondrial Cytochrome B ◽  
The Republic

AbstractHymenolepidid cestodes in Myodes glareolus from Lithuania and additional specimens originally attributed to Arostrilepis horrida from the Republic of Belarus are now referred to A. tenuicirrosa. Our study includes the first records of A. tenuicirrosa from the European (western) region of the Palearctic, and contributes to the recognition of A. horrida (sensu lato) as a complex of cryptic species distributed broadly across the Holarctic. Specimens of A. tenuicirrosa from Lithuania were compared to cestodes representing apparently disjunct populations in the eastern Palearctic based on structural characters of adult parasites and molecular sequence data from nuclear (ITS2) and mitochondrial (cytochrome b) genes. Morphological and molecular data revealed low levels of divergence between eastern and western populations. Phylogeographic relationships among populations and host biogeographic history suggests that limited intraspecific diversity within A. tenuicirrosa may reflect a Late Pleistocene transcontinental range expansion from an East Asian point of origin.

Homoplasy: from detecting pattern to determining process in evolution, but with a secondary role for morphology?

Zootaxa ◽  
2011 ◽  
Vol 2984 (1) ◽  
pp. 67 ◽  
Author(s):  
LEANDRO C. S. ASSIS ◽  
MARCELO R. DE CARVALHO ◽  
QUENTIN D. WHEELER
Keyword(s):  
Sequence Data ◽  
Morphological Characters ◽  
Flow Chart ◽  
Molecular Topology ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
Secondary Role ◽  
Molecular Phylogenetic ◽  
Phylogenetic Framework

David Wake and colleagues provided a thought-provoking review of the concept of homoplasy through the integration, within a phylogenetic framework, of genetic and developmental data (Wake et al. 2011). According to them (p. 1032) “Molecular sequence data have greatly increased our ability to identify homoplastic traits.” This is made clear, for example, in their flow chart for homoplasy detection (Figure 2, p. 1034), wherein homoplasy is discovered through the mapping of “traits of interest” onto a phylogram, a practice common in the molecular phylogenetic paradigm. The “mapping” is usually of morphological characters that are employed to support the chosen (molecular) topology, but which, as a consequence, do not themselves contribute to the formation of those topologies (Assis & Carvalho 2010).

scholarly journals Mitochondrial Genomes Provide Insights into the Phylogeny of Culicomorpha (Insecta: Diptera)

2019 ◽  
Vol 20 (3) ◽  
pp. 747 ◽  
Author(s):  
Xiao Zhang ◽  
Zehui Kang ◽  
Shuangmei Ding ◽  
Yuyu Wang ◽  
Chris Borkent ◽  
...  
Keyword(s):  
Phylogenetic Relationships ◽  
Sequence Data ◽  
Sister Group ◽  
Monophyletic Group ◽  
Phylogenomic Analysis ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
Genome Data ◽  
New Family ◽  
Mt Genome

Culicomorpha is a monophyletic group containing most bloodsucking lower dipterans, including many important vectors of pathogens. However, the higher-level phylogenetic relationships within Culicomorpha are largely unresolved, with multiple competing hypotheses based on molecular sequence data. Here we sequenced four nearly complete mitochondrial (mt) genomes representing four culicomorph families, and combined these new data with published mt genomes to reconstruct the phylogenetic relationships of all eight extant culicomorph families. We estimated phylogenies using four datasets and three methods. We also used four-cluster likelihood mapping to study potential incongruent topologies supported by the different datasets and phylogenetic questions generated by the previous studies. The results showed that a clade containing Ceratopogonidae, Thaumaleidae and Simuliidae was the sister group to all other Culicomorpha; in another clade, the Dixidae was basal to the remaining four families; Chaoboridae, Corethrellidae and Culicidae formed a monophyletic group and the Chironomidae was the sister group to this clade; Culicidae and Corethrellidae were sister groups in all trees. Our study provides novel mt genome data in Culicomorpha for three new family representatives, and the resulting mt phylogenomic analysis helps to resolve the phylogeny and taxonomy of Culicomorpha.

Phylogenetic relationships among nassariid gastropods

2000 ◽  
Vol 74 (5) ◽  
pp. 839-852 ◽  
Author(s):  
D. M. Haasl
Keyword(s):  
Phylogenetic Analysis ◽  
Phylogenetic Relationships ◽  
Sequence Data ◽  
Sister Group ◽  
Range Data ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
The Poor ◽  
The Family ◽  
Stratigraphic Position

Phylogenetic relationships within the neogastropod family Nassariidae are poorly understood as are relationships between the Nassariidae and other fossil and extant buccinid taxa. The poor resolution of nassariid and buccinoidean relationships is due to: 1) the complex distribution among these gastropods of characters commonly used in classification; 2) a number of Mesozoic and Paleogene genera whose relationships to extant buccinoidean lineages are poorly constrained; and 3) a lack of previous efforts to address these problems on a rigorous, phylogenetic basis.The results of a phylogenetic analysis of nassariid genera did not decisively support the monophyly of the family. The buccinid subfamily Photinae was an extant sister group to the Nassariinae in a phylogenetic analysis of extant taxa and on many cladograms from an analysis combining fossil and extant taxa. In addition, Buccitriton (representing the Paleogene Tritiaria group) was a sister taxon to the Nassariinae in all analyses in which it was included, regardless of the identity of the extant nassariine sister group. This suggests that the photines, which likely arose from a Tritiaria ancestor, are the closest living relatives to the Nassariinae. Many Paleogene fossil “buccinoid” taxa appear to be more distantly related to the Nassariinae and possibly to the rest of the nassariids as well. Stratigraphic range data combined with the results of this study suggest that the Nassariinae diversified rapidly in the early Miocene and achieved a cosmopolitan distribution early in their history. A largely Indo-Pacific subclade was consistently deeply-nested within the Nassariinae, suggesting that nassariines invaded the Indo-Pacific region most recently. The timing of this invasion is difficult to estimate but had occurred by the end of the Miocene. Further analyses using molecular sequence data, relative stratigraphic position, or focusing in more detail on the Paleogene taxa are required to resolve the identity of the sister group to the Nassariinae with greater confidence.

Molecular phylogenetics of snailfishes (Cottoidei: Liparidae) based on MtDNA and RADseq genomic analyses, with comments on selected morphological characters

Zootaxa ◽  
2019 ◽  
Vol 4642 (1) ◽  
pp. 1-79 ◽  
Author(s):  
JAMES WILDER ORR ◽  
INGRID SPIES ◽  
DUANE E. STEVENSON ◽  
GARY C. LONGO ◽  
YOSHIAKI KAI ◽  
...  
Keyword(s):  
Molecular Phylogenetics ◽  
Sequence Data ◽  
Morphological Characters ◽  
Molecular Sequence Data ◽  
Molecular Sequence ◽  
Genome Wide ◽  
The Pacific ◽  
The Family ◽  
Genomic Analyses ◽  
Gene Coi

Phylogenetic relationships of snailfishes of the family Liparidae were analyzed on the basis of two sets of molecular sequence data: one from the mitochondrial DNA cytochrome c oxidase subunit one gene (COI) and another from restriction-site associated genome-wide sequences (RADseq). The analysis of COI sequence data from at least 122 species of 18 genera from the Pacific, Atlantic, and Southern oceans resulted in a moderately well-resolved phylogeny among the major clades, albeit with significant polytomy among central clades. Nectoliparis was the sister of all other members of the family, followed by Liparis. Liparis, Careproctus, and Paraliparis were paraphyletic. Liparis was recovered in two closely related clades, with L. fucensis sister of all other liparids except Nectoliparis, and both Careproctus and Paraliparis were each recovered among at least three widely separated clades. The RADseq analysis of 26 species of 11 genera from the eastern North Pacific strongly confirmed the overall results of the COI analysis, with the exception of the paraphyly of Liparis due to the absence of L. fucensis. Our results show that the pelvic disc has been independently lost multiple times and the pectoral-fin girdle has been independently reduced in multiple lineages. 

Revision of Hyalopale (Chrysopetalidae; Phyllodocida; Annelida): an amphi-Atlantic Hyalopale bispinosa species complex and five new species from reefs of the Caribbean Sea and Indo-Pacific Oceans

Zootaxa ◽  
2019 ◽  
Vol 4671 (3) ◽  
pp. 339-368
Author(s):  
CHARLOTTE WATSON ◽  
EKIN TILIC ◽  
GREG W. ROUSE
Keyword(s):  
New Species ◽  
Indian Ocean ◽  
Species Complex ◽  
Sequence Data ◽  
Caribbean Sea ◽  
Sister Group ◽  
The Other ◽  
Western Pacific ◽  
Molecular Sequence Data ◽  
Molecular Sequence

The formerly monotypic taxon, Hyalopale bispinosa Perkins 1985 (Chrysopetalinae), is comprised of a cryptic species complex from predominantly tropical embayments and island reefs of the Western Atlantic and Indo-Pacific Oceans. Hyalopale species are of meiofaunal size (length: 1−2.8mm), but considered non-interstitial, with the majority of species inhabiting a singular habitat of shallow littoral zones among algae and epifauna overlying sediments in rubble. Hyalopale adults exhibit notochaetal fans characterized by the presence of lateral and midline notochaetal spines. Species of Hyalopale can be distinguished by the shape of glass-like notochaetal paleae and the number of densely stacked ribs. Hyalopale bispinosa forms a western and eastern Atlantic species complex, comprising the type species, Hyalopale bispinosa s.s., a comparatively larger form with the highest number of notochaetal paleael ribs from Florida, and Hyalopale cf. bispinosa, from the western and eastern Mediterranean, a smaller form with a similar notochaetal morphology to the latter. Unfortunately, no molecular sequence data is available for Hyalopale bispinosa s.s. Five new species are described, with molecular sequence data provided for three: Hyalopale leslieae sp. nov., a small form with a comparatively low number of paleal ribs, found from the Florida Keys to Belize, Caribbean Sea, H. zerofskii sp. nov. from southern California and Mexico, eastern Pacific and H. sapphiriglancyorum sp. nov., a distinctive species with the lowest number of paleael ribs, from Raja Ampat, Indonesia and the Great Barrier Reef, Queensland, western Pacific. Two other species are described from morphology alone: H. angeliensis sp. nov. from Dampier, Western Australia and Seychelle Islands, eastern Indian Ocean and H. furfuricula sp. nov. from the Red Sea and Mozambique, western Indian Ocean, possessing a unique paleal brow shape. While well supported as a clade, support for relationships within Hyalopale is low. Hyalopale cf. bispinosa (Mediterranean) was recovered as sister group to the remaining Hyalopale, with H. leslieae sp. nov. as sister to the Hyalopale Pacific clade, comprising H. zerofskii sp. nov. (eastern Pacific) and H. sapphiriglancyorum sp. nov. (western Pacific). Within Chrysopetalinae, Hyalopale and Paleanotus formed a clade that was the sister group to the other paleate chrysopetalids under maximum likelihood, though Paleanotus grouped with the other paleate forms under maximum parsimony. The adult morphology of Hyalopale species is compared with that exhibited in the larvae of Paleanotus species; based on these results, including possession of a shared notochaetal character, Hyalopale is considered to contain paedomorphic taxa. 

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