Constancy and change: taxonomic uncertainty in a probabilistic world

2000 ◽  
pp. 17-39
Keyword(s):  
Taxonomic Uncertainty

A history of Albertosaurus discoveries in Alberta, CanadaThis article is one of a series of papers published in this Special Issue on the theme Albertosaurus.

2010 ◽  
Vol 47 (9) ◽  
pp. 1197-1211 ◽  
Author(s):  
Darren H. Tanke ◽  
Philip J. Currie
Keyword(s):  
New Genus ◽  
Geographic Range ◽  
Special Issue ◽  
Southern Alberta ◽  
Considerable Confusion ◽  
Taxonomic Uncertainty ◽  
History Of ◽  
Information Politics ◽  
Horseshoe Canyon Formation

After many years of taxonomic uncertainty, Albertosaurus was established as a new genus in 1905, the year Alberta became a province of Canada. Gorgosaurus is a closely related tyrannosaurid from the Judithian beds of southern Alberta that was subsequently synonymized with Albertosaurus. Although most researchers consider the genera as distinct, there has been considerable confusion over the temporal and geographic range of Albertosaurus. Albertosaurus sarcophagus is only known from 13 skulls and (or) skeletons of varying completeness, and one (possibly two) bonebeds, all from the Horseshoe Canyon Formation (Campanian–Maastrichtian) of Alberta. Many of the major Albertosaurus specimens are scientifically compromised due to poor collection techniques, incomplete locality and stratigraphic information, politics, vandalism, accidents, gunplay, and landowner issues. The background of each specimen is discussed to eliminate some of the sources of confusion and to document how much of each specimen is preserved.

Taxonomy of Farrea (Porifera, Hexactinellida, Hexactinosida) from the southwestern Atlantic, with description of a new species and a discussion on the recognition of subspecies in Porifera

2011 ◽  
Vol 89 (3) ◽  
pp. 169-189 ◽  
Author(s):  
D. A. Lopes ◽  
E. Hajdu ◽  
H. M. Reiswig
Keyword(s):  
New Species ◽  
Comparative Analysis ◽  
Video Recording ◽  
First Record ◽  
Historical Overview ◽  
Southwestern Atlantic ◽  
Campos Basin ◽  
Taxonomic Uncertainty ◽  
Coral Banks ◽  
A New Species

The present study reports three species of Farrea Bowerbank, 1862 from Campos Basin (southwestern Atlantic): Farrea herdendorfi Duplessis and Reiswig, 2004, Farrea occa Bowerbank, 1862, and Farrea campossinus sp. nov. This is the first record of F. herdendorfi for the South Atlantic and only the second record of the species worldwide. Farrea occa is described and reported to form mass occurrences in the area’s sponge and coral banks, as seen in extensive video recording undertaken between 900 and 1100 m depth. The new species approaches Farrea foliascens Topsent, 1906 very closely, but differs in that its hooked anchorate clavules are much larger and the meshes of its dictyonal framework rather more irregular. Our thoughts on whether the proposed new species deserved species or subspecies rank led to an investigation on the usage of subspecies rank in Porifera. A historical overview, mainly contrasting Demospongiae and Hexactinellida is offered here. We concluded that no rule of thumb is readily made out from the comparative analysis of various authors’ taxonomic decisions. Until one such agreement is achieved, it appears to us that naming new subspecies should be objectively argued for, or better, totally avoided, as a useless further dimension to taxonomic uncertainty in poriferan classification.

scholarly journals Genetic structure and historical and contemporary gene flow of Astyanaxmexicanus in the Gulf of Mexico slope: a microsatellite-based analysis

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10784
Author(s):  
Rodolfo Pérez-Rodríguez ◽  
Sarai Esquivel-Bobadilla ◽  
Adonaji Madeleine Orozco-Ruíz ◽  
José Luis Olivas-Hernández ◽  
Francisco Javier García-De León
Keyword(s):  
Gene Flow ◽  
Gulf Of Mexico ◽  
Microsatellite Loci ◽  
Evolutionary History ◽  
Population Analysis ◽  
Morphological Variability ◽  
High Capacity ◽  
Genetic Population ◽  
Contemporary Gene Flow ◽  
Taxonomic Uncertainty

Background Astyanax mexicanus from the river basins of the Gulf of Mexico slope are small freshwater fish that usually live in large groups in different freshwater environments. The group is considered successful due to its high capacity for dispersal and adaptation to different habitats, and the species present high morphological variability throughout their distribution in Mexico. This has produced the most extreme morphotype of the group; the hypogeous or troglobite, which has no eyes or coloration, and is probably the cause of taxonomic uncertainty in the recognition of species across the entire range. Most studies of A. mexicanus have mainly focused on cave individuals, as well as their adjacent surface locations, providing an incomplete evolutionary history, particularly in terms of factors related to dispersal and the potential corridors used, barriers to gene flow, and distribution of genetic variability. The aim of the present study is to determine the population structure and the degree and direction of genetic flow in this complex taxonomic group, incorporating geographic locations not previously included in analyses using microsatellite loci. Our aim is to contribute to the knowledge of the intricate evolutionary history of A. mexicanus throughout most of its range. Methods The present study included a set of several cave and surface locations of A. mexicanus, which have been widely sampled along the Gulf of Mexico slope, in a genetic population analysis using 10 microsatellite loci. Results Ten genetic populations or lineages were identified. In these populations, gene flow was recorded at two time periods. Historical gene flow, both inter and intra-basin, was observed among surface populations, from surface to cave populations, and among cave populations, whereas recording of contemporary gene flow was limited to intra-basin exchanges and observed among surface populations, surface to cave populations, and cave populations.

scholarly journals Taxonomic Uncertainty and the Anomaly Zone: Phylogenomics Disentangle a Rapid Radiation to Resolve Contentious Species (Gila robusta complex) in the Colorado River

2019 ◽  
Author(s):  
Tyler K. Chafin ◽  
Marlis R. Douglas ◽  
Max R. Bangs ◽  
Bradley T. Martin ◽  
Steven M. Mussmann ◽  
...  
Keyword(s):  
Colorado River ◽  
Nominal Species ◽  
Rapid Radiation ◽  
Evolutionary Mechanisms ◽  
Phylogenetic Discordance ◽  
The Status ◽  
Taxonomic Uncertainty ◽  
Morphological Differences ◽  
Phylogenetic Models ◽  
Methodological Difficulties

AbstractSpecies is an indisputable unit for biodiversity conservation, yet their delimitation is fraught with both conceptual and methodological difficulties. A classic example is the taxonomic controversy surrounding the Gila robusta complex in the lower Colorado River of southwestern North America. Nominal species designations were originally defined according to weakly diagnostic morphological differences that conflicted with traditional genetic analyses. Consequently, the complex was re-defined as a single polytypic unit, with the proposed ‘threatened’ status of two being withdrawn at the federal level. Here, we utilized dense spatial and genomic sampling (N=387 and >22k loci) to re-evaluate the status of the complex, based on SNP-based coalescent and polymorphism-aware phylogenetic models. In doing so, all three species were supported as evolutionarily independent lineages, despite widespread phylogenetic discordance. To understand this discrepancy with past studies, we categorized evolutionary mechanisms driving discordance. We tested (and subsequently rejected) prior hypotheses suggesting that phylogenetic discord in the complex was hybridization-driven. Instead, we found the G. robusta complex to have diverged within the ‘anomaly zone’ of tree space and, as such, have accumulated inconsistent patterns of diversity which have confounded prior studies. After extending these analyses with phylogeographic modeling, we propose that this is reflective of a rapid radiation promoted by Plio-Pleistocene tectonism. Our results not only support resurrection of the three species as distinct entities, but also offer an empirical example of how phylogenetic discordance can be categorized in other recalcitrant taxa where variation is primarily partitioned at the species-level.

scholarly journals The curse of taxonomic uncertainty in biogeographical studies of free-living terrestrial protists: a case study of testate amoebae from Amsterdam Island

2009 ◽  
Vol 36 (8) ◽  
pp. 1551-1560 ◽  
Author(s):  
T. J. Heger ◽  
E. A. D. Mitchell ◽  
P. Ledeganck ◽  
S. Vincke ◽  
B. Van de Vijver ◽  
...  
Keyword(s):  
Testate Amoebae ◽  
Free Living ◽  
Taxonomic Uncertainty

scholarly journals Pre-Ediacaran multicellular life: harbinger of a Phanerozoic radiation

1992 ◽  
Vol 6 ◽  
pp. 47-47
Author(s):  
Nicholas J. Butterfield
Keyword(s):  
Cell Division ◽  
Cell Types ◽  
Cambrian Explosion ◽  
Taxonomic Resolution ◽  
Wall Structure ◽  
Molecular Evidence ◽  
Eukaryote Evolution ◽  
Taxonomic Uncertainty ◽  
Phylogenetic Hypotheses ◽  
Somerset Island

Multicellular organisms must have had a substantial pre-Ediacaran history, but the fossil evidence is sparse and often equivocal. The taxonomic resolution necessary to constrain phylogenetic hypotheses is limited largely to Lagerstätte-grade fossils that retain evidence of diagnostic cell division patterns. Uniseriate and multiseriate filaments in the 1267-723 Ma Hunting Formation, Somerset Island, derive from transverse and longitudinal intercalary cell division programs indistinguishable from those of the modern red alga Bangia, and establish a significantly pre-Ediacaran datum point for the Rhodophyta. Likewise, on the basis of a distinctive “segregative cell division”, three taxa of siphonocladalean green algae (Chlorophyta) are identified in the ca. 750 Ma Svanbergfjellet Formation, Spitsbergen. Process-bearing vesicles in the Svanbergfjellet sequence further compare with the germinating zoospores of the modern chromophyte alga Vaucheria, while convincing Vaucheria-like thalli are reported from ca. 900 Ma deposits in Siberia. The broad co-occurrence of multicellular Rhodophyta, Chlorophyta, and Chromophyta by at least 750 Ma ago accords well with molecular evidence that suggests the three principal algal clades diverged from a common ancestor during a brief but marked radiation relatively late in eukaryote evolution.Complex multicellularity featuring cellular and tissue(?) differentiation is also encountered in the pre-Ediacaran fossil record. A large ornate form in the Svanbergfjellet succession preserves at least six readily distinguishable cell types and, despite its taxonomic uncertainty, can be characterized as at least as complex as the most complex modern algae or fungi. No cellularity is preserved in the late Proterozoic macrofossil Tawuia; however, SEM and light microscopy of its isolated wall reveal a complex histology suggestive of a relatively advanced grade of multicellularity. Another Svanbergfjellet macrofossil has a distinct wall structure and bears a terminal pair of large reniform structures; if these prove to be truly bilaterally symmetrical, this fossil represents a grade of organization otherwise not recognized until the Ediacaran. Further analysis of these and other pre-Ediacaran ‘problematica’ may clarify their taxonomic relationships and promises to resolve at least some of the ‘Cambrian explosion’ into a meaningful sequence of evolutionary change.

Taxonomic uncertainty of a highly endangered brook damselfly, Copera tokyoensis Asahina, 1948 (Odonata: Platycnemididae), revealed by the mitochondrial gene genealogy

2011 ◽  
Vol 12 (3) ◽  
pp. 845-849 ◽  
Author(s):  
Takuya Kiyoshi ◽  
Jun-ichi Takahashi ◽  
Takehiko Yamanaka ◽  
Koichi Tanaka ◽  
Kenji Hamasaki ◽  
...  
Keyword(s):  
Mitochondrial Gene ◽  
Gene Genealogy ◽  
Taxonomic Uncertainty

A century of taxonomic uncertainty: re-description of two species of tapeworms (Diphyllobothriidea) from Arctic seals

Polar Biology ◽  
2018 ◽  
Vol 41 (12) ◽  
pp. 2543-2559 ◽  
Author(s):  
Bjoern C. Schaeffner ◽  
Oleg Ditrich ◽  
Roman Kuchta
Keyword(s):  
Taxonomic Uncertainty

scholarly journals Molecular differentiation of the Murraya paniculata Complex (Rutaceae: Aurantioideae: Aurantieae)

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Chung Huy Nguyen ◽  
G. Andrew C. Beattie ◽  
Anthony M. Haigh ◽  
Inggit Puji Astuti ◽  
David J. Mabberley ◽  
...  
Keyword(s):  
Sequence Data ◽  
Its Region ◽  
Molecular Dating ◽  
Putative Hybrid ◽  
Citrus Industry ◽  
Morphological Studies ◽  
Murraya Paniculata ◽  
Taxonomic Uncertainty ◽  
Liberibacter Asiaticus ◽  
Cryptic Taxa

Abstract Background Orange jasmine has a complex nomenclatural history and is now known as Murraya paniculata (L.) Jack. Our interest in this common ornamental stemmed from the need to resolve its identity and the identities of closely related taxa as hosts of the pathogen ‘Candidatus Liberibacter asiaticus’ and its vector Diaphorina citri. Understanding these microbe-vector-plant relationships has been hampered by taxonomic confusion surrounding Murraya at both the generic and specific levels. Results To resolve the taxonomic uncertainty, six regions of the maternally-inherited chloroplastal genome and part of the nuclear-encoded ITS region were amplified from 85 accessions of Murraya and Merrillia using the polymerase chain reaction (PCR). Clustering used maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI). Chronograms were produced for molecular dating, and to test the monophyly of Murraya rigorously, using selected accessions of Murraya and 26 accessions of the Rutaceae and Simarubaceae. Sequence data from the ITS and chloroplastal regions suggest that Murraya paniculata (sensu (Swingle WT and Reece CR, The Citrus Industry, p. 190–430, 1967)) can be separated into four distinct but morphologically somewhat cryptic taxa: Murraya paniculata (sensu (Mabberley DJ, Taxon 65:366–371, 2016)), M. elongata, M. sumatrana and M. lucida. In addition, Murraya omphalocarpa was identified as a putative hybrid of M. paniculata and M. lucida with two geographically isolated nothovarieties representing reciprocal crosses. Murraya is monophyletic, and molecular dating suggests that it diverged from Merrillia during the Miocene (23–5 Ma) with this Murraya group speciating and dispersing during the Middle Miocene onwards. Conclusions The accessions from Asia and Australasia used in this study grouped into biogeographical regions that match herbarium specimen records for the taxa that suggest natural allopatric distributions with limited overlap and hybridity. Murraya paniculata has been distributed around the world as an ornamental plant. The division of the Murraya paniculata complex into four species with a rare hybrid also confirms morphological studies.

Motile Aeromonas as agent of infections of the foot

1995 ◽  
Vol 85 (9) ◽  
pp. 505-508 ◽  
Author(s):  
M Wakabongo
Keyword(s):  
Second Generation ◽  
Antimicrobial Agents ◽  
Third Generation ◽  
Beta Lactam ◽  
Beta Lactam Antibiotics ◽  
Taxonomic Uncertainty ◽  
Post Traumatic ◽  
Third Generation Cephalosporins

Motile Aeromonas infections of the foot are caused mostly by post-traumatic incidence, occurring mostly during summer months. Serious complications such as osteomyelitis and amputation can result if the infections go untreated or are inadequately treated. The role of each species of motile Aeromonas in pathogenesis and response to antimicrobial agents is not well understood because of taxonomic uncertainty. As a group, motile Aeromonas respond well to aminoglycosides, second-generation and third-generation cephalosporins, quinolones, and some beta-lactam antibiotics.

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