What Is an “Arachnid”? Consensus, Consilience, and Confirmation Bias in the Phylogenetics of Chelicerata

The basal phylogeny of Chelicerata is one of the opaquest parts of the animal Tree of Life, defying resolution despite application of thousands of loci and millions of sites. At the forefront of the debate over chelicerate relationships is the monophyly of Arachnida, which has been refuted by most analyses of molecular sequence data. A number of phylogenomic datasets have suggested that Xiphosura (horseshoe crabs) are derived arachnids, refuting the traditional understanding of arachnid monophyly. This result is regarded as controversial, not least by paleontologists and morphologists, due to the widespread perception that arachnid monophyly is unambiguously supported by morphological data. Moreover, some molecular datasets have been able to recover arachnid monophyly, galvanizing the belief that any result that challenges arachnid monophyly is artefactual. Here, we explore the problems of distinguishing phylogenetic signal from noise through a series of in silico experiments, focusing on datasets that have recently supported arachnid monophyly. We assess the claim that filtering by saturation rate is a valid criterion for recovering Arachnida. We demonstrate that neither saturation rate, nor the ability to assemble a molecular phylogenetic dataset supporting a given outcome with maximal nodal support, is a guarantor of phylogenetic accuracy. Separately, we review empirical morphological phylogenetic datasets to examine characters supporting Arachnida and the downstream implication of a single colonization of terrestrial habitats. We show that morphological support of arachnid monophyly is contingent upon a small number of ambiguous or incorrectly coded characters, most of these tautologically linked to adaptation to terrestrial habitats.

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The primary divisions of life: a phylogenomic approach employing composition-heterogeneous methods

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2009.0034 ◽

2009 ◽

Vol 364 (1527) ◽

pp. 2197-2207 ◽

Cited By ~ 82

Author(s):

Peter G. Foster ◽

Cymon J. Cox ◽

T. Martin Embley

Keyword(s):

Sequence Data ◽

Phylogenetic Signal ◽

Amino Acid Sequences ◽

Rate Variation ◽

Molecular Sequence Data ◽

Protein Coding ◽

Molecular Sequence ◽

Heterogeneous Models ◽

Matrix Heterogeneity ◽

Rna Genes

The three-domains tree, which depicts eukaryotes and archaebacteria as monophyletic sister groups, is the dominant model for early eukaryotic evolution. By contrast, the ‘eocyte hypothesis’, where eukaryotes are proposed to have originated from within the archaebacteria as sister to the Crenarchaeota (also called the eocytes), has been largely neglected in the literature. We have investigated support for these two competing hypotheses from molecular sequence data using methods that attempt to accommodate the across-site compositional heterogeneity and across-tree compositional and rate matrix heterogeneity that are manifest features of these data. When ribosomal RNA genes were analysed using standard methods that do not adequately model these kinds of heterogeneity, the three-domains tree was supported. However, this support was eroded or lost when composition-heterogeneous models were used, with concomitant increase in support for the eocyte tree for eukaryotic origins. Analysis of combined amino acid sequences from 41 protein-coding genes supported the eocyte tree, whether or not composition-heterogeneous models were used. The possible effects of substitutional saturation of our data were examined using simulation; these results suggested that saturation is delayed by among-site rate variation in the sequences, and that phylogenetic signal for ancient relationships is plausibly present in these data.

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Noteworthy record of the Ethiopian genet, Genetta abyssinica, (Carnivora, Viverridae) from Djibouti informs its phylogenetic position within Genetta

Mammalia ◽

10.1515/mammalia-2017-0081 ◽

2019 ◽

Vol 83 (2) ◽

pp. 180-189 ◽

Cited By ~ 2

Author(s):

Adam W. Ferguson ◽

Houssein R. Roble ◽

Molly M. McDonough

Keyword(s):

Phylogenetic Relationships ◽

Sequence Data ◽

Alternative Hypothesis ◽

Phylogenetic Analyses ◽

Phylogenetic Position ◽

Sister Relationship ◽

Molecular Sequence Data ◽

Molecular Sequence ◽

Molecular Phylogenetic ◽

Relationship Of

AbstractThe molecular phylogeny of extant genets (Carnivora, Viverridae,Genetta) was generated using all species with the exception of the Ethiopian genetGenetta abyssinica. Herein, we provide the first molecular phylogenetic assessment ofG. abyssinicausing molecular sequence data from multiple mitochondrial genes generated from a recent record of this species from the Forêt du Day (the Day Forest) in Djibouti. This record represents the first verified museum specimen ofG. abyssinicacollected in over 60 years and the first specimen with a specific locality for the country of Djibouti. Multiple phylogenetic analyses revealed conflicting results as to the exact relationship ofG. abyssinicato otherGenettaspecies, providing statistical support for a sister relationship to all other extant genets for only a subset of mitochondrial analyses. Despite the inclusion of this species for the first time, phylogenetic relationships amongGenettaspecies remain unclear, with limited nodal support for many species. In addition to providing an alternative hypothesis of the phylogenetic relationships among extant genets, this recent record provides the first complete skeleton of this species to our knowledge and helps to shed light on the distribution and habitat use of this understudied African small carnivore.

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

Zootaxa ◽

10.11646/zootaxa.2984.1.3 ◽

2011 ◽

Vol 2984 (1) ◽

pp. 67 ◽

Cited By ~ 4

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).

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Across Lydekker's Line - first report of mite harvestmen (Opiliones : Cyphophthalmi : Stylocellidae) from New Guinea

Invertebrate Systematics ◽

10.1071/is06046 ◽

2007 ◽

Vol 21 (3) ◽

pp. 207 ◽

Cited By ~ 28

Author(s):

Ronald M. Clouse ◽

Gonzalo Giribet

Keyword(s):

Sequence Data ◽

Phylogenetic Analyses ◽

New Guinea ◽

Single Male ◽

Molecular Sequence Data ◽

Molecular Sequence ◽

The Family ◽

Biogeographic Region ◽

Molecular Phylogenetic ◽

History Of

Opiliones (harvestmen) in the suborder Cyphophthalmi are not known to disperse across oceans and each family in the suborder is restricted to a clear biogeographic region. While undertaking a revisionary study of the South-east Asian family Stylocellidae, two collections of stylocellids from New Guinea were noted. This was a surprising find, since the island appears never to have had a land connection with Eurasia, where the rest of the family members are found. Here, 21 New Guinean specimens collected from the westernmost end of the island (Manokwari Province, Indonesia) are described and their relationships to other cyphophthalmids are analysed using molecular sequence data. The specimens represent three species, Stylocellus lydekkeri, sp. nov., S. novaguinea, sp. nov. and undescribed females of a probable third species, which are described and illustrated using scanning electron microscope and stereomicroscope photographs. Stylocellus novaguinea, sp. nov. is described from a single male and it was collected with a juvenile and the three females of the apparent third species. Molecular phylogenetic analyses indicate that the new species are indeed in the family Stylocellidae and they therefore reached western New Guinea by dispersing through Lydekker’s line – the easternmost limit of poor dispersers from Eurasia. The New Guinean species may indicate at least two episodes of oceanic dispersal by Cyphophthalmi, a phenomenon here described for the first time. Alternatively, the presence in New Guinea of poor dispersers from Eurasia may suggest novel hypotheses about the history of the island.

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Phylogenomic resolution of scorpions reveals multilevel discordance with morphological phylogenetic signal

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.2953 ◽

2015 ◽

Vol 282 (1804) ◽

pp. 20142953 ◽

Cited By ~ 63

Author(s):

Prashant P. Sharma ◽

Rosa Fernández ◽

Lauren A. Esposito ◽

Edmundo González-Santillán ◽

Lionel Monod

Keyword(s):

Fossil Record ◽

Evolutionary History ◽

Digestive System ◽

Sequence Data ◽

Phylogenetic Signal ◽

Molecular Sequence Data ◽

Molecular Sequence ◽

Single Origin ◽

As Species ◽

First Time

Scorpions represent an iconic lineage of arthropods, historically renowned for their unique bauplan, ancient fossil record and venom potency. Yet, higher level relationships of scorpions, based exclusively on morphology, remain virtually untested, and no multilocus molecular phylogeny has been deployed heretofore towards assessing the basal tree topology. We applied a phylogenomic assessment to resolve scorpion phylogeny, for the first time, to our knowledge, sampling extensive molecular sequence data from all superfamilies and examining basal relationships with up to 5025 genes. Analyses of supermatrices as well as species tree approaches converged upon a robust basal topology of scorpions that is entirely at odds with traditional systematics and controverts previous understanding of scorpion evolutionary history. All analyses unanimously support a single origin of katoikogenic development, a form of parental investment wherein embryos are nurtured by direct connections to the parent's digestive system. Based on the phylogeny obtained herein, we propose the following systematic emendations: Caraboctonidae is transferred to Chactoidea new superfamilial assignment ; superfamily Bothriuroidea revalidated is resurrected and Bothriuridae transferred therein; and Chaerilida and Pseudochactida are synonymized with Buthida new parvordinal synonymies .

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Molecular phylogeny of Ceriantharia (Cnidaria: Anthozoa) reveals non-monophyly of traditionally accepted families

Zoological Journal of the Linnean Society ◽

10.1093/zoolinnean/zlz158 ◽

2019 ◽

Vol 190 (2) ◽

pp. 397-416 ◽

Cited By ~ 2

Author(s):

Anny C Forero Mejia ◽

Tina Molodtsova ◽

Carina Östman ◽

Giorgio Bavestrello ◽

Greg W Rouse

Keyword(s):

Sequence Data ◽

Alternative Hypothesis ◽

Phylogenetic Analyses ◽

Molecular Sequence Data ◽

Molecular Sequence ◽

Phylogenetic Reconstructions ◽

Molecular Phylogenetic ◽

Integrative Study ◽

Nuclear Loci ◽

Significant Support

Abstract We present an integrative study with molecular phylogenetic reconstructions and morphological assessment across the three Ceriantharia families: Arachnactidae, Botrucnidiferidae and Cerianthidae. The Arachnactidae specimens (Isarachnanthus spp.) form a well-supported clade, whereas Cerianthidae and Botrucnidiferidae are not recovered as monophyletic. Consequently, the validity of the suborder Spirularia is questioned. Cerianthus was recovered as polyphyletic and Ceriantheomorphe may prove to be a junior synonym of Cerianthus. The taxonomic position of Cerianthus cf. mortenseni is also discussed. All specimens identified on morphology as belonging to Pachycerianthus are recovered as a clade. Further revision of taxa within Ceriantharia is necessary. Molecular phylogenetic analyses based on six mitochondrial or nuclear loci place Ceriantharia as sister to Hexacorallia s.s., but with no significant support relative to an alternative hypothesis that it is the sister taxon to Octocorallia. Further molecular sequence data and taxon sampling will be needed to resolve the position of Ceriantharia.

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Was Gordon Robilliard right? Integrative systematics suggest that Dendronotus diversicolor (multicolor frond-aeolis) is a valid species

Canadian Journal of Zoology ◽

10.1139/cjz-2016-0096 ◽

2016 ◽

Vol 94 (11) ◽

pp. 793-799 ◽

Cited By ~ 7

Author(s):

I. Ekimova ◽

Á. Valdés ◽

D. Schepetov ◽

A. Chichvarkhin

Keyword(s):

Sequence Data ◽

Distinct Species ◽

External Morphology ◽

Morphological Data ◽

Valid Species ◽

Colour Pattern ◽

Molecular Sequence Data ◽

Molecular Sequence ◽

Wide Range ◽

Integrative Systematics

Nudibranch molluscs of the genus Dendronotus Alder and Hancock, 1845 are widely distributed in the Northern Hemisphere. Taxonomic studies on the genus Dendronotus have been problematic due to high variability in the colour pattern of many species, as well as in the external morphology and anatomy. In the present paper, we studied specimens of Dendronotus from northern Pacific presumably belonging to the species Dendronotus albus MacFarland, 1966 (white frond-aeolis). Molecular and morphological data revealed the existence of two distinct species among the material examined: D. albus, which has a wide range from Kamchatka and the Kurile Islands (from where we report this species for the first time) to California in North America, and the pseudocryptic species Dendronotus diversicolor Robilliard, 1970 (multicolor frond-aeolis), which has been previously considered a junior synonym of D. albus. Dendronotus diversicolor occurs from California, USA, to British Columbia, Canada, in sympatry with D. albus. Dendronotus albus and D. diversicolor can be clearly distinguished by colour pattern, internal and external morphology, and molecular sequence data. Despite some similarities in radular and external morphology between D. albus and D. diversicolor, these two species are phylogenetically distant and belong to different clades within the genus Dendronotus, which suggests convergent evolution.

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Molecular sequence data from populations of Bryoria fuscescens s. lat. in the mountains of central Spain indicates a mismatch between haplotypes and chemotypes

The Lichenologist ◽

10.1017/s0024282915000274 ◽

2015 ◽

Vol 47 (5) ◽

pp. 279-286 ◽

Cited By ~ 5

Author(s):

Carlos G. Boluda ◽

Víctor J. Rico ◽

Ana Crespo ◽

Pradeep K. Divakar ◽

David L. Hawksworth

Keyword(s):

Sequence Data ◽

Population Level ◽

Central Spain ◽

Molecular Sequence Data ◽

Short Branch ◽

Molecular Sequence ◽

Forest Sites ◽

Molecular Phylogenetic ◽

Taxonomic Changes ◽

Different Parts

AbstractIn order to confirm and investigate the extent of reported mismatches between chemotypes and molecular sequence data in Bryoria fuscescens s. lat., we examined 15 morphologically similar thalli from each of three Pinus forest sites in the Sistema Central of central Spain. Three thalli were rejected due to infections by Phacopsis huuskonenii (not previously published from Spain). The remaining 42 thalli represented nine ITS rDNA haplotypes and four chemotypes (by TLC): fumarprotocetraric and protocetraric acids; norstictic and connorstictic acids; psoromic acid; and fumarprotocetraric, protocetraric and psoromic acids. The molecular phylogenetic tree was characterized by extremely short branch lengths, often only with a single mutational difference, and a single haplotype could have different chemical products. In some cases, adjacent specimens represented different chemotypes, and three thalli appeared to be mixed individuals. Consistency of both molecular and chemical data within individual specimens was demonstrated by examining four different parts of each thallus, which showed only a difference in the location of psoromic acid in some. This is the first population-level study of this taxon, and so it is premature to propose taxonomic changes at this time. Further populations in different parts of the geographical range of this widespread complex now need to be analyzed, and more sensitive chemical analyses conducted, in order to understand the basis of the variability and determine the appropriate taxonomic treatment.

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The status of Myriangiaceae (Dothideomycetes)

Phytotaxa ◽

10.11646/phytotaxa.176.1.22 ◽

2014 ◽

Vol 176 (1) ◽

pp. 219 ◽

Cited By ~ 10

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.

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Apertochrysa (Neuroptera: Chrysopidae): A heterogeneric phantom?

Zootaxa ◽

10.11646/zootaxa.4238.1.4 ◽

2017 ◽

Vol 4238 (1) ◽

pp. 58 ◽

Cited By ~ 5

Author(s):

ATSUSHI MOCHIZUKI ◽

CHARLES S. HENRY ◽

PETER DUELLI

Keyword(s):

Type Species ◽

Morphological Traits ◽

New Genus ◽

Sequence Data ◽

New Combination ◽

Wing Venation ◽

Monophyletic Clade ◽

Molecular Sequence Data ◽

Molecular Sequence ◽

Group Relationships

The small lacewing genus Apertochrysa comprises species from Africa, Asia and Australia. All lack a tignum, but otherwise resemble distantly related genera. We show that Apertochrysa does not form a monophyletic clade, based on analyses of molecular sequence data and morphological traits such as the presence and shape of the male gonapsis, wing venation, and larval setae. Apertochrysa kichijoi forms a clade with Eremochrysa, Suarius and Chrysemosa, whereas A. albolineatoides belongs to a clade that includes Cunctochrysa. Apertochrysa albolineatoides should become a new combination as Cunctochrysa albolineatoides, while A. kichijoi will have to be transferred to a new genus. The Australian A. edwardsi, the African A. eurydera and the type species of the genus Apertochrysa, A. umbrosa, join the large Pseudomallada group. Relationships of A. umbrosa are less certain, because for it we could amplify only one of the three nuclear genes used in the overall analysis. However, in all morphological traits tested, that species strongly resembles A. edwardsi and A. eurydera and thus is very likely just another exceptional Pseudomallada lacking a tignum. The fate of the genus name Apertochrysa depends on additional molecular and morphological analyses of A. umbrosa.

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