Allozyme Evidence for Cryptic Speciation in Sympatric Populations of Nassarius spp. (Mollusca: Gastropoda)

1997 ◽  
Vol 77 (3) ◽  
pp. 773-784 ◽  
Author(s):  
Andrés Sanjuan ◽  
Marcos Losada-Perez ◽  
Emilio Rolan
Keyword(s):  
Taxonomic Status ◽  
Sympatric Populations ◽  
Separate Species ◽  
Preliminary Screening ◽  
North West ◽  
Enzyme Loci ◽  
Nassarius Reticulatus ◽  
Considerable Debate ◽  
Ría De Vigo ◽  
The Subject

The Nassarius reticulatus complex (Mollusca: Gastropoda) is a common and morphologically variable organism of the Lusitanian marine province. The taxonomic status of the different morphs has been the subject of considerable debate for over a century. About 50 individuals of each N. nitidus and N. reticulatus morphs were collected in November 1994 from the same area (Ria de Vigo, north-west Iberian Peninsula). Preliminary screening by allozyme electrophoresis for 27 enzymes resolved 24 presumptive enzyme loci. There were no deviations from the Hardy-Weinberg expected proportions at most polymporphic loci for any morph. Five and two enzyme loci were completely and partially diagnostic loci, respectively, between the morphs. The genetic identity of morphs (1=0.658 ±0.095) was characteristic of congeneric species. The absence of electrophoretically recognizable hybrids in sympatric populations provides clear evidence that the two morphs are reproductively isolated within the study area. These genetic results corroborate other reported biochemical, morphological and behavioural differences between the morphs. Consequently, these data strongly suggest that the taxa N. nitidus and N. reticulatus must be considered as separate species.

Re-examination of the taxonomy of the Macrobrachium australiense Holthuis (Decapoda : Palaemonidae) species-complex: molecular evidence for a single species

2004 ◽  
Vol 18 (2) ◽  
pp. 227 ◽  
Author(s):  
Nicholas P. Murphy ◽  
John W. Short ◽  
Christopher M. Austin
Keyword(s):  
Genetic Relationships ◽  
Mitochondrial Gene ◽  
Taxonomic Status ◽  
Single Species ◽  
Gene Region ◽  
Molecular Evidence ◽  
Morphological Divergence ◽  
Separate Species ◽  
North West ◽  
North East

The freshwater shrimp Macrobrachium australiense is distributed throughout the majority of inland, north-west, north-east and eastern drainages. Owing to the large amount of morphological divergence, both between and within catchments, this species has proven to be taxonomically difficult and, until recently, consisted of three separate species, each with subsequent subspecies. This study uses nucleotide sequences from the 16S rRNA mitochondrial gene region to investigate the genetic relationships between populations and confirm the taxonomic status of M. australiense. The results from sequencing an approximately 450-bp fragment from this gene region from M. australiense sampled from 12 locations across inland, eastern and northern Australia identified very little variation. The variation found between 16S M. australiense haplotypes is much less than that found between Macrobrachium species, indicating that it is in fact a single species. The results are concordant with a recent morphological revision of Australian species in which nominal taxa of the M. australiense complex were synonymised.

scholarly journals Genetic differentiation in Gammarus fossarum and G. caparti (Crustacea, Amphipoda) with reference to G. pulex pulex in northwestern Europe

1989 ◽  
Vol 59 (3) ◽  
pp. 127-139 ◽  
Author(s):  
Maarten Scheepmaker ◽  
Jan van Dalfsen
Keyword(s):  
Genetic Differentiation ◽  
Taxonomic Status ◽  
Species Level ◽  
Gammarus Fossarum ◽  
Northern France ◽  
Enzyme Loci

Genetic differentiation among G. fossarum Koch, 1835 from different stations in Germany, Switzerland, Belgium and northern France, and the closely related Belgian form G. caparti Pètre-Stroobants, 1980 was investigated by electrophoresis at 20 enzyme loci. Although morphologically variable, geographically distant populations of G. cf. fossarum were hitherto considered conspecific. In the present study, populations of G. cf. fossarum and G. caparti were examined with reference to G. pulex pulex as an estimate for genetic differentiation at the species level. With G. p. pulex as a standard, genetic differentiation among geographically distant populations of G. cf. fossarum is occasionally observed at species level. The populations of G. caparti studied were shown to be genetically very similar to certain populations of G. fossarum. The taxonomic status of G. caparti and the genetically distinct forms of G. fossarum is discussed.

Electrophoretic characterization of Solomon Islands populations of Nyctimene and Rousettus (Chiroptera: Pteropodidae).

2003 ◽  
Vol 25 (1) ◽  
pp. 41 ◽  
Author(s):  
JM Macaranas ◽  
D Colgan ◽  
S Ingleby
Keyword(s):  
Papua New Guinea ◽  
Solomon Islands ◽  
Taxonomic Status ◽  
Genetic Distances ◽  
Allozyme Data ◽  
Separate Species ◽  
Bismarck Archipelago ◽  
A Minor ◽  
Two Populations

The taxonomic status of fruitbats belonging to the genera Nyctimene and Rousettus from the Solomon Islands was investigated using allozyme electrophoresis. Two populations from the Bismarck Archipelago (Papua New Guinea) were included as reference profiles. The allozyme data at 23 loci assigned all specimens into either Nyctimene albiventer or Nyctimene major. The N. albiventer specimens comprised two subspecies, N. a. papuanus from the Bismarck Archipelago and N. a. bougainville from the Solomon Islands. No support was evident for bougainville being a separate species, and indeed the data suggest that N. a. bougainville encompasses the previously described species N. malaita and subspecies N. a. minor. Genetic distances between populations of R. amplexicaudatus from the Bismarck Archipelago and the Solomon Islands were generally low, supporting recent morphological assessments that the subspecies hedigeri, from the majority of the Solomon Islands, should be considered synonymous with subspecies brachyotis. An individual from Choiseul (Solomon Islands) with a distinctive allozyme profile is the only evidence of taxonomic complexity in R. amplexicaudatus.

scholarly journals Origin of the eastern brownsnake, Pseudonaja textilis (Dumeril, Bibron and Dumeril) (Serpentes: Elapidae: Hydrophiinae) in New Guinea: evidence of multiple dispersals from Australia, and comments on the status of Pseudonaja textilis pughi Hoser 2003

Zootaxa ◽  
2008 ◽  
Vol 1703 (1) ◽  
pp. 47 ◽  
Author(s):  
DAVID J. WILLIAMS ◽  
MARK O'SHEA ◽  
ROLAND L. DAGUERRE ◽  
CATHARINE E. POOK ◽  
WOLFGANG WÜSTER ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Taxonomic Status ◽  
New Guinea ◽  
Physical Geography ◽  
Sea Level Changes ◽  
Migration Routes ◽  
Arnhem Land ◽  
The Status ◽  
The Subject ◽  
Western Migration

Pseudonaja textilis is a widespread and common snake in eastern parts of Australia, but its distribution in New Guinea is poorly understood, and the origin of the New Guinea populations and its timing have been the subject of much speculation. Phylogenetic analysis of mitochondrial DNA sequences from three New Guinea populations of P. textilis indicates that New Guinea was colonised from two independent eastern and western migration routes most likely in the Pleistocene. One dispersal event from northern Queensland led to the populations in eastern New Guinea (Milne Bay, Oro and Central Provinces, Papua New Guinea), whereas another, from Arnhem Land to central southern New Guinea, led to the populations from the Merauke area, Indonesian Papua. The results are consistent with the effects of Pleistocene sea level changes on the physical geography of Australasia, and are thus suggestive of a natural rather than anthropogenic origin of the New Guinea populations. The taxonomic status of the New Guinean populations is discussed.

Simulations of light effects on the human circadian pacemaker: implications for assessment of intrinsic period

1996 ◽  
Vol 270 (1) ◽  
pp. R271-R282 ◽  
Author(s):  
E. B. Klerman ◽  
D. J. Dijk ◽  
R. E. Kronauer ◽  
C. A. Czeisler
Keyword(s):  
Quantitative Model ◽  
Circadian System ◽  
Ambient Light ◽  
Circadian Pacemaker ◽  
Dark Cycle ◽  
Considerable Debate ◽  
Experimental Protocols ◽  
Light Effects ◽  
The Subject ◽  
Experimental Substantiation

The sensitivity of the human circadian system to light has been the subject of considerable debate. Using computer simulations of a recent quantitative model for the effects of light on the human circadian system, we investigated these effects of light during different experimental protocols. The results of the simulations indicate that the nonuniform distribution over the circadian cycle of exposure to ordinary room light seen in classical free-run studies, in which subjects select their exposure to light and darkness, can result in an observed period of approximately 25 h, even when the intrinsic period of the subject's endogenous circadian pacemaker is much closer to 24 h. Other simulation results suggest that accurate assessment of the true intrinsic period of the human circadian pacemaker requires low ambient light intensities (approximately 10-15 lx) during scheduled wake episodes, desynchrony of the imposed light-dark cycle from the endogenous circadian oscillator, and a study length of at least 20 days. Although these simulations await further experimental substantiation, they highlight the sensitivity to light of the human circadian system and the potential confounding influence of light on the assessment of the intrinsic period of the circadian pacemaker.

Analytic taxonomy and notes on marine, brackish-water and estuarine Gastrotricha

Zootaxa ◽  
2010 ◽  
Vol 2392 (1) ◽  
pp. 1 ◽  
Author(s):  
WILLIAM D. HUMMON ◽  
M. ANTONIO TODARO
Keyword(s):  
Taxonomic Status ◽  
Species Group ◽  
Zoological Nomenclature ◽  
New Name ◽  
New Family ◽  
Analytic Review ◽  
The Family ◽  
Species Inquirenda ◽  
The Subject ◽  
Species Inquirendae

Marine Gastrotricha, both Macrodasyida and Chaetonotida, are the subject of an analytic review, citing taxonomic status of names, authorships of taxa, and those responsible for changes, in accordance with the International Code of Zoological Nomenclature, 4 th ed. (1999). Notes are included with regard to taxonomic usage so as to guide workers in the future. Among the proposed novelties are: within Macrodasyida, to restrict the family Lepidodasyidae Remane, 1927 to the genus Lepidodasys Remane, 1926, and to establish a new family, Cephalodasyidae with Cephalodasys Remane, 1926 as its type-species to house the remaining genera and species that have been contained in the polyphyletic family Lepidodasyidae. Hemidasys agaso Claparède, 1867 is considered extinct, and the new name Tetranchyroderma antenniphorum is proposed for Tetranchyroderma antennatum Luporini, Magagnini & Tongiorgi, 1973; in addition, five species are here considered to be species inquirendae: Dactylopodola weilli d'Hondt, 1965, Paradasys nipponensis Sudzuki, 1976, Macrodasys indicus Kutty & Nair, 1969. Tetranchyroderma forceps d’Hondt & Balsamo, 2009 and Turbanella plana (Giard, 1904b). Among Chaetonotida: the Xenotrichula velox-species group Ruppert, 1979 and the Xenotrichula intermedia-species group Ruppert, 1979 were given each the rank of subgenus. Chaetonotus pleuracanthus Remane, 1926 is rejected as a synonym for Chaetonotus marinus Giard, 1904; Chaetonotus somniculosus Mock, 1979 is transferred to the genus Halichaetonotus, the new name Halichaetonotus euromarinus is proposed for Halichaetonotus spinosus Mock, 1979, and Xenotrichula carolinensis Ruppert, 1979 is re-established. Heteroxenotrichula variocirrata d'Hondt, 1966 is here considered to be species inquirenda.

scholarly journals Genetic diversity and structure of the binturong Arctictis binturong (Carnivora: Viverridae) – status of the elusive Palawan binturong and implications for conservation

2019 ◽  
Author(s):  
Géraldine Veron ◽  
Agathe Debruille ◽  
Pauline Kayser ◽  
Desamarie Antonette P Fernandez ◽  
Aude Bourgeois
Keyword(s):  
Taxonomic Status ◽  
The Philippines ◽  
The Other ◽  
Restricted Range ◽  
Crucial Importance ◽  
Separate Species ◽  
Mitochondrial Markers ◽  
Molecular Approaches ◽  
Captive Populations ◽  
Genetic Diversity And Structure

Abstract The binturong or bearcat is a forest mesocarnivore ranging from Nepal to Indonesia and the Philippines. Several subspecies of binturongs are recognized but a revision is needed. The binturong from Palawan was described as a species and is now considered a subspecies, but its status has never been checked using molecular approaches. Owing to its restricted range and the pressure on its habitat, the Palawan binturong may be endangered. It is, therefore, of crucial importance to clarify its taxonomic status, particularly for the management of captive populations. We sequenced one nuclear and two mitochondrial markers for binturongs from locations across the species range and from zoos. Our results provide an assessment of the genetic polymorphism and structure within the binturong, resulting in two groups, corresponding to the Indochinese and the Sundaic regions. Within the latter were found the Palawan binturongs on one side, and an individual from Sulu archipelago (a locality not reported before) on the other side. The Palawan binturongs form a monophyletic group, genetically close to Bornean binturongs, which suggests that they may have dispersed from Borneo, and represents a lineage worth preserving, but which is not a separate species nor a separate subspecies.

The Taxonomic Status of Littorina Neglecta: A Comment to Grahame, Mill, Double and Hull

1993 ◽  
Vol 73 (1) ◽  
pp. 249-249 ◽  
Author(s):  
K. Johannesson ◽  
B. Johannesson
Keyword(s):  
Western Europe ◽  
Short Communication ◽  
Taxonomic Status ◽  
Morphological Characters ◽  
Littorina Saxatilis ◽  
Separate Species ◽  
Close Coupling ◽  
Allozyme Loci ◽  
North Western ◽  
High Shore

In a short communication Grahame et al. (1992) argue against our finding that Littorina neglecta Bean is an ecotype of Littorina saxatilis (Olivi) rather than a separate species (Johannesson & Johannesson, 1990b). Unfortunately, Grahame et al. (1992) have miss-represented our earlier paper, and we feel the need to refute their arguments.In populations from north-western Europe we studied morphological characters used to separate Littorina neglecta from L. saxatilis. We found that intermediate shapes were common and, furthermore, we found no close coupling among characters used to define L. neglecta (Johannesson & Johannesson, 1990a). We further analysed the genetic variation in five strongly polymorphic allozyme loci. In four loci we found a pattern that indicated that L. neglecta is not reproductively isolated from L. saxatilis. In the fifth locus, Aat-1, we found consistent differences between populations of L. neglecta (from the low shore) and L. saxatilis (from the high shore). Similar differences were observed between low and high shore populations in Sweden where, however, no snails of neglecta-type were present.

scholarly journals Taxonomic status of the intracellular bacterium Wolbachia pipientis

2007 ◽  
Vol 57 (3) ◽  
pp. 654-657 ◽  
Author(s):  
N. Lo ◽  
C. Paraskevopoulos ◽  
K. Bourtzis ◽  
S. L. O'Neill ◽  
J. H. Werren ◽  
...  
Keyword(s):  
Biological Control ◽  
Culex Pipiens ◽  
Type Strain ◽  
Taxonomic Status ◽  
Intracellular Bacterium ◽  
Wolbachia Pipientis ◽  
Molecular Sequence ◽  
Filarial Nematodes ◽  
The Subject ◽  
Medical Importance

Wolbachia pipientis is a maternally inherited, intracellular bacterium found in more than 20 % of all insects, as well as numerous other arthropods and filarial nematodes. It has been the subject of a growing number of studies in recent decades, because of the remarkable effects it has on its arthropod hosts, its potential as a tool for biological control of arthropods of agricultural and medical importance and its use as a target for treatment of filariasis. W. pipientis was originally discovered in cells of the mosquito Culex pipiens and is the only formally described member of the genus. Molecular sequence-based studies have revealed a number of phylogenetically diverse strains of W. pipientis. Owing to uncertainty about whether W. pipientis comprises more than one species, researchers in the field now commonly refer to W. pipientis simply as Wolbachia. In this note, we briefly review higher-level phylogenetic and recombination studies of W. pipientis and propose that all the intracellular symbionts known to cluster closely with the type strain of W. pipientis, including those in the currently recognized supergroups (A–H), are officially given this name.

Waiting for Bobos: Displacement and Impeded Gentrification in a Midwestern City

2017 ◽  
Vol 16 (2) ◽  
pp. 145-168 ◽  
Author(s):  
Chase M. Billingham
Keyword(s):  
Historical Case Study ◽  
Lower Income ◽  
Archival Research ◽  
Skid Row ◽  
Historical Case ◽  
Considerable Debate ◽  
The Subject ◽  
Midwestern City

The degree to which lower–income residents are displaced by the process of gentrification has been the subject of considerable debate. Displacement is generally framed as a possible, and potentially remediable, outcome of gentrification. This portrayal of the link between gentrification and displacement is problematic, though, because gentrification can proceed without substantial displacement, while displacement frequently occurs in the absence of gentrification. In this article, I use a historical case study to examine the link between displacement and gentrification. Drawing on archival research and media accounts of redevelopment over the course of 50 years in Wichita, Kansas, I demonstrate how a displacement–first strategy has characterized all attempts to transform the city's “skid row” into the hub of a gentrified downtown core, and I describe how, despite widespread displacement, the gentrification of downtown Wichita has been largely unsuccessful. I discuss the implications of these findings for sociological theories of gentrification and displacement.

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