A taxonomic reevaluation of North American Daphnia (Crustacea: Cladocera). I. The D. similis complex

1993 ◽  
Vol 71 (5) ◽  
pp. 908-925 ◽  
Author(s):  
Paul D. N. Hebert ◽  
Terrie L. Finston
Keyword(s):  
Species Recognition ◽  
Distinct Species ◽  
The Other ◽  
Allozyme Analysis ◽  
Distance Analysis ◽  
Daphnia Similis ◽  
Cyclic Parthenogenesis ◽  
Morphological Differences ◽  
Genetic Distance Analysis

Allozyme analysis of 28 populations of Daphnia similis s.l. from the western United States and Canada indicated the presence of three different species. One taxon, D. salina, is newly described and a second species, D. exilis, previously synonymized with D. similis, is also shown to be distinct. Species recognition is not solely reliant on allozyme analysis, as morphological differences among the species are conspicuous. Daphnia salina is a halophile, while the other two species occur in habitats of lower but variable salinity. All three taxa appear to reproduce by cyclic parthenogenesis, although levels of genetic diversity were so low in D. salina that determination of its breeding system was tentative. Genetic distance analysis suggested that D. salina diverged from the other two species some 27 million years ago, whereas D. exilis and D. similis separated 9 million years ago.

scholarly journals IX. Remarks concerning the Natural-Historical Determination of Diallage

1826 ◽  
Vol 10 (1) ◽  
pp. 127-147
Author(s):  
W. Haidinger
Keyword(s):  
Fixed Point ◽  
Natural History ◽  
Distinct Species ◽  
The Other ◽  
Accurate Information ◽  
External Appearance ◽  
Slight Degree ◽  
The One

The following paper contains the results of a series of inquiries, which lead to the conclusion, that the mineral called Smaragdite by Saussure, does not form a species of its own; but that this name has been given to a compound of certain varieties of two distinct species, Augite and Hornblende, the natural-historical species of paratomous and hemiprismatic Augite-spar.Owing in part to the slight degree of resemblance prevailing among its varieties, the authors who have described them differ so essentially in opinion, that I am obliged to go into various details, both respecting the external appearance of the mineral itself, and of the opinions of mineralogists, in order to afford a correct view of the natural-historical species, to which these varieties belong, since this is the basis upon which every system, and, indeed, all accurate information in natural history, is founded, and the fixed point to which the one and the other must be referred.

CYTOTAXONOMY AND SEX DETERMINATION OF RUMEX PAUCIFOLIUS

1956 ◽  
Vol 34 (2) ◽  
pp. 261-268 ◽  
Author(s):  
Áskell Löve ◽  
Nina Sarkar
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
The Other ◽  
Large Chromosome ◽  
Dioecious Species ◽  
The Third ◽  
Male Sex ◽  
Morphological Differences

The western North American dioecious species Rumex paucifolius is shown to be a tetraploid with 2n = 28 chromosomes. It is the third tetraploid known within the subgenus Acetosa, and the first polyploid dioecious taxon of that group, the others having either 2n = 14 ♂, 15 ♀ (R. Acetosa and relatives), or 2n = 8 ♂, 9 ♀ (R. hastatulus). The sex chromosomes of R. paucifolius are of the XX:XY type, the male sex being heterogametic. The X is a large chromosome, while the Y is the smallest chromosome of the complement. The mechanism of sex determination of R. paucifolius follows the Melandrium–Acetosella scheme with strongly epistatic male determinants in the Y–chromosome. Other dioecious Acetosae follow the Drosophila–Acetosa scheme of sex determination with a balance between the number of X and autosome complements, the Y being sexually inert. It is concluded from the observed cytogenetical and morphological differences that R. paucifolius should constitute a section of its own, Paucifoliae, which should be placed as far as possible from the section Acetosa, though within the same subgenus. The other American dioecious endemic, R. hastatulus, is placed in a subsection of the section Acetosa.

A cytotaxonomic study of Australian Cardamine

1968 ◽  
Vol 16 (3) ◽  
pp. 515 ◽  
Author(s):  
N Thurling
Keyword(s):  
Reproductive Isolation ◽  
Native Species ◽  
Cytogenetic Study ◽  
Morphological Differentiation ◽  
Distinct Species ◽  
The Other ◽  
F1 Hybrids ◽  
Altitudinal Distribution ◽  
South Wales ◽  
Morphological Differences

A cytogenetic study of Cardamine, based on material collected in southern New South Wales and the Australian Capital Territory, indicated the presence of at least six distinct species in this area. Two species, the 16-chromosome C. hirsuta and the 32- chromosome C. flexuosa, were introduced with white settlement. The other four species are native to the area, occupying a variety of habitats between sea-level and 7200 ft. One species, with a somatic chromosome number of 64, is confined to altitudes below 4000 ft, whereas the other three species (2n = 48) are found only above 4000 ft. Of the 48-chromosome species, one comprises a single population found at Mt. Franklin and the remaining two are confined to particular altitudinal ranges, one between 4000 and 5400 ft and the other between 5200 and 7200 ft. All four native species are completely isolated from one another by the inviability of the F1 hybrids. Within species, however, all populations were fully interfertile and there was no evidence of any other form of reproductive isolation. Despite the magnitude of reproductive isolation there were no distinct morphological differences between the native species except in the case of the 48-chromosome form from Mt. Franklin, which had entire rather than pinnate leaves. The other three species were in fact more comparable to ecotypes in respect of their altitudinal distribution and the degree of morphological differentiation. Speciation mechanisms involved in the evolution of the native species of Cardamine are discussed.

Emended description and resurrection of Sciaphila tosaensis and S. megastyla (Triuridaceae)

Phytotaxa ◽  
2019 ◽  
Vol 413 (3) ◽  
pp. 231-243 ◽  
Author(s):  
KENJI SUETSUGU ◽  
AKIHIKO KINOSHITA ◽  
TIAN-CHUAN HSU
Keyword(s):  
Genetic Divergence ◽  
Taxonomic Status ◽  
Distinct Species ◽  
Molecular Data ◽  
Genetic Distances ◽  
The Other ◽  
Morphological Data ◽  
Flowering Stage ◽  
Emended Description ◽  
Morphological Differences

This paper presents a re-evaluation of the taxonomic status of Sciaphila tosaensis and S. megastyla (Triuridaceae) distributed in Japan and Taiwan. Based on the detailed morphological data, we concluded that these two species should both be treated as distinct species rather than synonyms of S. secundiflora. Sciaphila tosaensis differs from S. secundiflora and S. megastyla in having very narrow male perianth segments and female perianth segments distinctly shorter than male perianth segments. Sciaphila megastyla differs from the other two species in having very conspicuous style and stigma that is ca. 1.5 times as long as ovary in the flowering stage. Furthermore, a lectotype is designated of S. megastyla because its holotype has been lost. Molecular data also showed that there is considerable genetic divergence between S. tosaensis and S. megastyla, supporting that the morphological differences are mirrored by their genetic distances.

scholarly journals Integrative taxonomy resuscitates two species in the Lasioglossum villosulum complex (Kirby, 1802) (Hymenoptera: Apoidea: Halictidae)

2019 ◽  
Author(s):  
Alain Pauly ◽  
Grégoire Noël ◽  
Gontran Sonet ◽  
David G. Notton ◽  
Jean-Luc Boevé
Keyword(s):  
Bayesian Inference ◽  
Species Complex ◽  
Phylogenetic Trees ◽  
Dna Barcode ◽  
Distinct Species ◽  
Integrative Taxonomy ◽  
The Other ◽  
Candidate Species ◽  
Morphological Differences ◽  
Pseudocryptic Species

Morphological and allozyme analyses suggested the occurrence of a pseudocryptic species in the Lasioglossum villosulum (Kirby, 1802) species complex (Hymenoptera: Halictidae). We analysed the morphology of more than 1500 specimens and the DNA barcode fragment of the cytochrome c oxidase subunit I (COI) of 102 specimens of this species complex from several Palaearctic countries. Our phylogenetic tree reconstructions, based on maximum likelihood and Bayesian inference revealed one clade corresponding to all specimens morphologically identified as Lasioglossum medinai (Vachal, 1895) and one divergent specimen morphologically identified as Lasioglossum berberum (Benoist, 1941). The other specimens, morphologically identified as L. villosulum, aggregated into at least three other lineages in our phylogenetic trees. The tree-based species delineations methods based on the Generalized Mixed Yule Coalescent (GMYC) model and the Bayesian Poisson Tree Process (bPTP) identified five to ten candidate species within the L. villosulum species complex, with L. medinai and L. berberum consistently recognized as separated from all other candidate species. Diagnostic morphological differences were found among L. medinai, L. berberum and the remaining specimens identified as L. villosulum. No diagnostic morphological differences were found to distinguish the different phylogenetic candidate species or lineages found within L. villosulum and L. medinai. Thus, both genetic and morphological approaches support the existence of L. medinai and L. berberum as distinct species from L. villosulum.

Determination of the lattice translation across {110} APBs in GaAs

1988 ◽  
Vol 46 ◽  
pp. 600-601
Author(s):  
D.R. Rasmussen ◽  
N.-H. Cho ◽  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Lower Energy ◽  
Antiphase Boundary ◽  
The Other ◽  
Boundary Structure ◽  
Interface Plane ◽  
Inversion Symmetry ◽  
High Angle ◽  
Equilibrium Distance

Domains in GaAs can exist which are related to one another by the inversion symmetry, i.e., the sites of gallium and arsenic in one domain are interchanged in the other domain. The boundary between these two different domains is known as an antiphase boundary [1], In the terminology used to describe grain boundaries, the grains on either side of this boundary can be regarded as being Σ=1-related. For the {110} interface plane, in particular, there are equal numbers of GaGa and As-As anti-site bonds across the interface. The equilibrium distance between two atoms of the same kind crossing the boundary is expected to be different from the length of normal GaAs bonds in the bulk. Therefore, the relative position of each grain on either side of an APB may be translated such that the boundary can have a lower energy situation. This translation does not affect the perfect Σ=1 coincidence site relationship. Such a lattice translation is expected for all high-angle grain boundaries as a way of relaxation of the boundary structure.

Determination of the Burgers vector of a dislocation in a Fe-Mn alloy by weak-beam image in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 330-331
Author(s):  
Y. Ishida ◽  
H. Ishida ◽  
K. Kohra ◽  
H. Ichinose
Keyword(s):  
High Order ◽  
Simulation Technique ◽  
The Other ◽  
Image Simulation ◽  
Diffraction Vector ◽  
Burgers Vector ◽  
Weak Beam ◽  
Beam Image ◽  
Edge Component

IntroductionA simple and accurate technique to determine the Burgers vector of a dislocation has become feasible with the advent of HVEM. The conventional image vanishing technique(1) using Bragg conditions with the diffraction vector perpendicular to the Burgers vector suffers from various drawbacks; The dislocation image appears even when the g.b = 0 criterion is satisfied, if the edge component of the dislocation is large. On the other hand, the image disappears for certain high order diffractions even when g.b ≠ 0. Furthermore, the determination of the magnitude of the Burgers vector is not easy with the criterion. Recent image simulation technique is free from the ambiguities but require too many parameters for the computation. The weak-beam “fringe counting” technique investigated in the present study is immune from the problems. Even the magnitude of the Burgers vector is determined from the number of the terminating thickness fringes at the exit of the dislocation in wedge shaped foil surfaces.

A scanning electron microscopic study of the eggs of Culicoides variipennis (Diptera: Ceratopogonidae)

1987 ◽  
Vol 45 ◽  
pp. 884-885 ◽  
Author(s):  
R. A. Nunamaker ◽  
C. E. Nunamaker ◽  
B. C. Wick
Keyword(s):  
Distinct Species ◽  
Hemorrhagic Disease ◽  
Insect Vector ◽  
Electron Microscopic ◽  
Important Species ◽  
Scanning Electron Microscopic Study ◽  
Laboratory Colony ◽  
Culicoides Variipennis ◽  
Morphological Differences ◽  
Scanning Electron

Culicoides variipennis (Coquillett) is probably the most economically important species of biting midge in the U.S. due to its involvement in the transmission of bluetongue (BT) disease of sheep, cattle and ruminant wildlife, and epizootic hemorrhagic disease (EHD) of deer. Proposals have been made to recognize the eastern and western populations of this insect vector as distinct species. Others recommend use of the term “variipennis complex” until such time that the necessary biosystematic studies have been made to determine the genetic nature and/or minute morphological differences within the population structure over the entire geographic range of the species. Increasingly, students of ootaxonomy are relying on scanning electron microscopy (SEM) to assess chorionic features. This study was undertaken to provide comparative chorionic data for the C. variipennis complex.Culicoides variipennis eggs were collected from a laboratory colony maintained in Laramie, Wyoming.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

Procedures for the Quantitative Determination of Autoprothrombin C

1962 ◽  
Vol 08 (03) ◽  
pp. 434-441 ◽  
Author(s):  
Edmond R Cole ◽  
Ewa Marciniak ◽  
Walter H Seegers
Keyword(s):  
Quantitative Determination ◽  
Plasma Sample ◽  
Quantitative Measure ◽  
The Other ◽  
Clotting Time ◽  
Bovine Plasma ◽  
Autoprothrombin C

SummaryTwo quantitative procedures for autoprothrombin C are described. In one of these purified prothrombin is used as a substrate, and the activity of autoprothrombin C can be measured even if thrombin is in the preparation. In this procedure a reaction mixture is used wherein the thrombin titer which develops in 20 minutes is proportional to the autoprothrombin C in the reaction mixture. A unit is defined as the amount which will generate 70 units of thrombin in the standardized reaction mixture. In the other method thrombin interferes with the result, because a standard bovine plasma sample is recalcified and the clotting time is noted. Autoprothrombin C shortens the clotting time, and the extent of this is a quantitative measure of autoprothrombin C activity.

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