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.

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.

scholarly journals Determination of species boundaries of Selais fish from Arut River, Central Kalimantan based on 16S mitochondrial gene using Bayesian approach

2020 ◽  
Vol 28 ◽  
pp. 01003
Author(s):  
Tuty Arisuryanti ◽  
Bella Ulin Nikmah ◽  
Tomi Kasayev ◽  
Lukman Hakim
Keyword(s):  
Bayesian Approach ◽  
Genetic Relationships ◽  
Mitochondrial Gene ◽  
Single Species ◽  
Morphological Characters ◽  
Valid Species ◽  
Species Boundaries ◽  
Phylogenetic Study ◽  
Central Kalimantan ◽  
Molecular Phylogenetic

Selais fish is difficult to discriminate with other Silurid fish species based on morphological characters. As a result, the valid species of selais fish is uncertain. Therefore, a molecular phylogenetic study was needed to clarify species boundaries and to addresses genetic relationships of the selais fish. In this study, 16S mitochondrial gene of ten selais samples collected from Arut River (Central Kalimantan) were sequenced, from which a Bayesian trees was generated. Result revealed monophyletic of selais fish which is revealed as a single species. The Bayesian inference showed that the selais fish clade is distinguished with two other genus, Kryptopterus and Ompok, by its sequence differences. This finding can address species boundaries of selais fish using Bayesian approach, but the name of the selais species has not been clarified.

Genetic Divergence Between South African Helcion Species and North-East Atlantic H. Pellucidum (Mollusca: Patellogastropoda)

1997 ◽  
Vol 77 (4) ◽  
pp. 1139-1150 ◽  
Author(s):  
L.I. Weber ◽  
D.R. Gray ◽  
A.N. Hodgson ◽  
S.J. Hawkins
Keyword(s):  
South African ◽  
Genetic Divergence ◽  
Genetic Relationships ◽  
Taxonomic Status ◽  
Genetic Distances ◽  
Group Method ◽  
Congeneric Species ◽  
East Atlantic ◽  
North East ◽  
The North

Allozyme electrophoresis was used to estimate the genetic divergence between three species of South African Helcion and the north-east Atlantic H. pellucidum (Patellidae). At a finer level the genetic relationships among South African Helcion were explored. Twenty-one loci were resolved for all the species. High values of expected heterozygosities (0·202–0·341) were found for the genus. Phenetic analysis (UPGMA (unweighted pair-group method with artihmetic averaging) and Distance Wagner Procedure) and cladistic parsimony methods (alleles as binary characters and loci as multistate unordered characters) agreed in showing the same topology for the tree which represents the genetic relationships among Helcion species. The north-east Atlantic H. pellucidum was the most divergent species showing high values of Nei's genetic distances (1·423–1·654) with its South African congeners. In the literature such values of genetic divergence have been associated with non-congeneric species. The degree of genetic divergence (0·351–0·615) found within the South African branch was characteristic for congeneric species. The results of this study supported the monophyletic condition of this branch, and showed H. pectunculus and H. pruinosus to be more closely related to each other than to H. dunkeri. Nevertheless, the monophyly of the genus Helcion is uncertain and therefore its taxonomic status was questioned. A possible independent origin for northern and southern hemisphere species of Helcion is considered.

scholarly journals High genetic diversity and presence of genetic structure characterise the Corso-Sardinian endemics Ruta corsica and Ruta lamarmorae (Rutaceae)

2018 ◽  
Author(s):  
Marilena Meloni ◽  
Caterina Angela Dettori ◽  
Andrea Reid ◽  
Gianluigi Bacchetta ◽  
Laetitia Hugot ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Biological Diversity ◽  
Taxonomic Status ◽  
Single Species ◽  
Dispersal Ability ◽  
Separate Species ◽  
High Genetic Diversity ◽  
History Of

SummaryCorsica and Sardinia form one of the ten areas with highest biodiversity in the Mediterranean and are considered one of the priority regions for conservation in Europe. In order to preserve the high levels of endemism and biological diversity at different hierarchical levels, knowledge of the evolutionary history and current genetic structure of Corso-Sardinian endemics is instrumental. Microsatellite markers were newly developed and used to study the genetic structure and taxonomic status of Ruta corsica and Ruta lamarmorae, rare endemics of Corsica and Sardinia, respectively, and previously considered a single species. Our analyses identified high levels of genetic variation within each species (P=0.883, He=0.543 for R. corsica; P=0.972, He=0.627 for R. lamarmorae). Intrinsic traits of the species (hermaphroditism, proterandry and polyploidy) and island-dependent factors (i.e. age, origin and history of the islands) might explain the detected high levels of genetic variation. We discovered differentiation between R. corsica and R. lamarmorae, and genetic structure within each species, which are consistent with the observation of low dispersal ability for both species. Our genetic results support the recent taxonomic classification of R. corsica and R. lamarmorae as separate species and suggest that they diverge at only few loci. One R. corsica population (SA) strongly differed from all other studied populations and appeared to be the product of hybridization between the two species in STRUCTURE analyses. Our results provide important insights for the conservation of the two rare endemics. Further genetic analyses are recommended for R. lamarmorae and for population SA (R. corsica).

scholarly journals Fritzolenellus lapworthi (Peach and Horne, 1892) from the lower Cambrian(Cambrian Series 2) Bastion Formation of North-East Greenland.

2008 ◽  
Vol 56 ◽  
pp. 1-10
Author(s):  
Martin Stein
Keyword(s):  
Lower Cambrian ◽  
Single Species ◽  
East Greenland ◽  
North West ◽  
North East ◽  
Stage 4

Fossil collections from the lower Cambrian (Cambrian Series 2) Bastion Formation at Albert Heim Bjerge in North-East Greenland acquired during 1950 and 1951 contain some 60 specimens of olenellid trilobites. Although morphologically variable, the material can be attributed to a single species, Fritzolenellus lapworthi (Peach and Horne, 1892), previously known from the ‘Fucoid’ Beds of north-west Scotland. Immature specimens allow a first, limited, description of the ontogeny of Fritzolenellus. The presence of F. lapworthi in North-East Greenland offers an important tie point for correlation of Olenellus-bearing strata (Cambrian Series 2, Stage 4) across eastern Laurentia.

A new volcanic province: evidence from glacial erratics in western North Greenland

2000 ◽  
pp. 35-41 ◽  
Author(s):  
Peter R. Dawes ◽  
Bjørn Thomassen ◽  
T.I. Hauge Andersson
Keyword(s):  
Volcanic Rocks ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Common Component ◽  
Volcanic Province ◽  
North West ◽  
North East ◽  
The North ◽  
Surficial Deposits ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Dawes, P. R., Thomassen, B., & Andersson, T. H. (2000). A new volcanic province: evidence from glacial erratics in western North Greenland. Geology of Greenland Survey Bulletin, 186, 35-41. https://doi.org/10.34194/ggub.v186.5213 _______________ Mapping and regional geological studies in northern Greenland were carried out during the project Kane Basin 1999 (see Dawes et al. 2000, this volume). During ore geological studies in Washington Land by one of us (B.T.), finds of erratics of banded iron formation (BIF) directed special attention to the till, glaciofluvial and fluvial sediments. This led to the discovery that in certain parts of Daugaard-Jensen Land and Washington Land volcanic rocks form a common component of the surficial deposits, with particularly colourful, red porphyries catching the eye. The presence of BIF is interesting but not altogether unexpected since BIF erratics have been reported from southern Hall Land just to the north-east (Kelly & Bennike 1992) and such rocks crop out in the Precambrian shield of North-West Greenland to the south (Fig. 1; Dawes 1991). On the other hand, the presence of volcanic erratics was unexpected and stimulated the work reported on here.

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

scholarly journals DISTRIBUTION AND RACE COMPOSITION OF DOWNY MILDEW (Plasmopara halstedii (Farl.) Berl. and de Toni) IN BULGARIA / EXTENSION Y RAZAS DEL MILDIU (Plasmopara halstedii (Farl.) Berl. y de Toni) EN BULGARIA / ÉTENDUE ET RACES DE LA ROUILLE (Plasmopara halstedii (Farl.) Berl. and de Toni) EN BULGARIE

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 25-32
Author(s):  
P.S. Shindrova
Keyword(s):  
Downy Mildew ◽  
Resistance Gene ◽  
The Other ◽  
Plasmopara Halstedii ◽  
North West ◽  
North East ◽  
Race 1 ◽  
Race 2 ◽  
Production Areas ◽  
Number Of Authors

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.

Excavations at Fishbourne, 1963. Third Interim Report

1964 ◽  
Vol 44 (1) ◽  
pp. 1-8
Keyword(s):  
Interim Report ◽  
The West ◽  
Civic Society ◽  
North West ◽  
The Third ◽  
North East ◽  
The North ◽  
The Future ◽  
Set Up

Early in 1963 much of the land occupied by the Roman building at Fishbourne was purchased by Mr. I. D. Margary, M.A., F.S.A., and was given to the Sussex Archaeological Trust. The Fishbourne Committee of the trust was set up to administer the future of the site. The third season's excavation, carried out at the desire of this committee, was again organized by the Chichester Civic Society.1 About fifty volunteers a day were employed from 24th July to 3rd September. Excavation concentrated upon three main areas; the orchard south of the east wing excavated in 1962, the west end of the north wing, and the west wing. In addition, trial trenches were dug at the north-east and north-west extremities of the building and in the area to the north of the north wing. The work of supervision was carried out by Miss F. Pierce, M.A., Mr. B. Morley, Mr. A. B. Norton, B.A., and Mr. J. P. Wild, B.A. Photography was organized by Mr. D. B. Baker and Mrs. F. A. Cunliffe took charge of the pottery and finds.

scholarly journals On tho proportions of the prevailing winds, the mean temperature, and depth of rain in the climate of London, computed through a cycle of Eighteen Years, or periods of the Moon’s declination

1843 ◽  
Vol 4 ◽  
pp. 300-300
Keyword(s):  
The Moon ◽  
Fair Weather ◽  
North West ◽  
West Wind ◽  
North East ◽  
East Wind ◽  
The North ◽  
The Common ◽  
The Mean ◽  
Solar Influence

In this paper the author investigates the periodical variations of the winds, rain and temperature, corresponding to the conditions of the moon’s declination, in a manner similar to that he has already followed in the case of the barometrical variations, on a period of years extending from 1815 to 1832 inclusive. In each case he gives tables of the average quantities for each week, at the middle of which the moon is in the equator, or else has either attained its maximum north or south declination. He thus finds that a north-east wind is most promoted by the constant solar influence which causes it, when the moon is about the equator, going from north to south; that a south-east wind, in like manner, prevails most when the moon is proceeding to acquire a southern declination ; that winds from the south and west blow more when the moon is in her mean degrees of declination, going either way, than with a full north or south declination ; and that a north-west wind, the common summer and fair weather wind of the climate, affects, in like manner, the mean declination, in either direction, in preference to the north or south, and most when the moon is coming north. He finds the average annual depth of rain, falling in the neighbourhood of London, is 25’17 inches.

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