Morphological variation in Romanomermis culicivorax Ross and Smith, 1976 (Nematoda: Mermithidae)

1982 ◽  
Vol 60 (5) ◽  
pp. 1007-1011
Author(s):  
J. Curran
Keyword(s):  
Morphological Variation ◽  
Developmental Stages ◽  
Morphological Characters ◽  
Mating Pair ◽  
Species Diagnosis ◽  
Reliable Diagnosis ◽  
Single Mating

The morphological characters lateral chord structure, head, tail, vagina and spicule shape, which are those most frequently used in the diagnosis of mermithid species, were highly variable within the progeny of a single mating pair of Romanomermis culicivorax Ross and Smith, 1976. In the light of this variability the usefulness of these characters in species diagnosis is discussed and it is concluded that a series of specimens at various developmental stages are required for reliable diagnosis.

Morphometrics of Romanomermis culicivorax Ross and Smith, 1976 (Nematoda: Mermithidae)

1981 ◽  
Vol 59 (12) ◽  
pp. 2365-2374 ◽  
Author(s):  
J. Curran
Keyword(s):  
Discriminant Analysis ◽  
Environmental Factors ◽  
Host Species ◽  
Intraspecific Variability ◽  
Species Level ◽  
Mating Pair ◽  
Species Diagnosis ◽  
Single Mating

Intraspecific variability and the influence of environmental factors on the morphometrics of Romanomermis culicivorax Ross and Smith, 1976 were determined by rearing the progeny of a single mating pair under different parasite intensities, host species, and temperatures. Individual measurements were frequently affected by environment and discriminant analysis revealed differences in overall shape between sibling populations. These effects were not constant within or between sexes. The growth relationships between measurements were examined and because of allometry a number of ratios commonly used in mermithid taxonomy at the species level were rejected. This led to an evaluation of morphometrics in species diagnosis.

Further Observations on the Morphology of Heterodera schachtii, with Remarks on the Bionomics of a strain attacking Mangolds in Britain

1929 ◽  
Vol 7 (3) ◽  
pp. 119-140 ◽  
Author(s):  
Marjorie J. Triffitt
Keyword(s):  
Sugar Beet ◽  
Developmental Stages ◽  
Morphological Characters ◽  
Heterodera Schachtii ◽  
Adult Males ◽  
Morphological Variations ◽  
Size And Shape ◽  
Morphological Studies ◽  
Comparative Survey

In a previous publication the morphological characters of a strain of H. schachtii specialised on the potato in Lincolnshire were discussed. The size and shape of the brown cysts, size of the eggs and first stage larvæ and the general characters of the adult males of this strain were compared with those of a strain attacking potatoes in Rostock, Mecklenburg, for which the specific name H. rostochiensis was suggested by Wollenweber 1923.Considerable dimensional variations were found to exist in the Lincolnshire strain, and a study of the literature on the morphological characters of H. schachtii specialised on sugar-beet and oats, showed equally wide divergencies between the findings of different workers. A certain amount of preserved material of infected roots of beet and oats being available to the writer, as many developmental stages as possible were extracted from these, on which similar morphological studies were carried out. Thus a fairly complete comparative survey of H. schachtii specialised on beet, oats and potatoes was completed, and the morphological variations between the strains were found to be insufficient to justify the separation of the strain specialised on potato from those on beet and oats. The name H. rostochicnsis was, therefore, deemed a synonym for H. schachtii.

scholarly journals Variations in genetic structure and male genitalia suggest recent lineage diversification in the Neotropical dung beetle complex Canthon cyanellus (Scarabaeidae: Scarabaeinae)

2020 ◽  
Vol 131 (3) ◽  
pp. 505-520
Author(s):  
Janet Nolasco-Soto ◽  
Mario E Favila ◽  
Alejandro Espinosa De Los Monteros ◽  
Jorge González-Astorga ◽  
Gonzalo Halffter ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Morphological Variation ◽  
Male Genitalia ◽  
Morphological Variability ◽  
Dung Beetle ◽  
Morphological Characters ◽  
Taxonomic Assignment ◽  
Morphometric Variation ◽  
Evolutionary Forces ◽  
Significant Genetic Structure

Abstract We analysed the genetic divergence and morphology of the aedeagus (i.e. phallobase and parameres) in Canthon cyanellus at different geographical levels. The results from both approaches were compared with the current taxonomic assignment of the C. cyanellus complex, which includes three subspecies. We found a high variation in all the morphological characters of the aedeagus in the populations analysed; the morphometric variation was not geographically structured, either by population or by region. The genealogical analysis indicates a significant genetic structure that does not match either the morphological variation in the male genitalia or the previous subspecific taxonomic classification. Our results suggest that the morphological variation of the aedeagus is seemingly not an isolating reproductive barrier and that the intra- and interpopulation morphological variability of the aedeagus in the C. cyanellus complex does not permit the division into several species. We suggest that other evolutionary forces, such as genetic drift and sexual selection, have influenced the evolution of the male genitalia and the incipient differentiation of this species complex.

scholarly journals Genetic consequences of a century of protection: serial founder events and survival of the little spotted kiwi ( Apteryx owenii )

2013 ◽  
Vol 280 (1762) ◽  
pp. 20130576 ◽  
Author(s):  
Kristina M. Ramstad ◽  
Rogan M. Colbourne ◽  
Hugh A. Robertson ◽  
Fred W. Allendorf ◽  
Charles H. Daugherty
Keyword(s):  
Genetic Variation ◽  
Long Island ◽  
Genetic Bottleneck ◽  
Island Population ◽  
Mating Pair ◽  
Terrestrial Vertebrates ◽  
Census Size ◽  
Single Mating ◽  
Genetic Bottlenecks ◽  
Founder Events

We present the outcome of a century of post-bottleneck isolation of a long-lived species, the little spotted kiwi ( Apteryx owenii , LSK) and demonstrate that profound genetic consequences can result from protecting few individuals in isolation. LSK were saved from extinction by translocation of five birds from South Island, New Zealand to Kapiti Island 100 years ago. The Kapiti population now numbers some 1200 birds and provides founders for new populations. We used 15 microsatellite loci to compare genetic variation among Kapiti LSK and the populations of Red Mercury, Tiritiri Matangi and Long Islands that were founded with birds from Kapiti. Two LSK native to D'Urville Island were also placed on Long Island. We found extremely low genetic variation and signatures of acute and recent genetic bottleneck effects in all four populations, indicating that LSK have survived multiple genetic bottlenecks. The Long Island population appears to have arisen from a single mating pair from Kapiti, suggesting there is no genetic contribution from D'Urville birds among extant LSK. The N e / N C ratio of Kapiti Island LSK (0.03) is exceptionally low for terrestrial vertebrates and suggests that genetic diversity might still be eroding in this population, despite its large census size.

Morphological variation in the genus Juliomys (Rodentia: Cricetidae: Sigmodontinae) and taxonomic status of Juliomys anoblepas (Winge 1887) from the Quaternary of Southeast Brazil

Zootaxa ◽  
2020 ◽  
Vol 4861 (3) ◽  
pp. 429-443
Author(s):  
CAROLINA PIRES ◽  
MARCELO WEKSLER ◽  
CIBELE R. BONVICINO
Keyword(s):  
Principal Component Analysis ◽  
Morphological Variation ◽  
Morphological Analysis ◽  
Principal Component ◽  
Taxonomic Status ◽  
Morphological Characters ◽  
The Other ◽  
Anterior Portion ◽  
Living Species ◽  
Qualitative Characters

The region of Lagoa Santa, Minas Gerais, Brazil, is one of the most important karstic areas of the Brazilian Quaternary due to the faunistic diversity of living and extinct forms. Among them, some taxa remain poorly studied, as is the case of Calomys anoblepas Winge 1887. Despite the recent allocation of the taxon within Juliomys, its description and morphological analysis are condensed, based on comparative few specimens and on few informative characters. In this study, we investigate characters proposed to distinguish species of Juliomys, and reevaluate the taxonomic status of the fossil Juliomys anoblepas. We analyzed 80 cranio-dental morphological characters in 233 specimens represented by the four species currently recognized: J. pictipes (Osgood 1933), J. rimofrons Oliveira & Bonvicino 2002, J. ossitenuis Costa, Pavan, Leite & Fagundes 2007, and J. ximenezi Christoff, Vieira, Oliveira, Gonçalves, Valiati & Tomasi 2016. We also performed principal component analysis on eight craniodental measurements available for the J. anoblepas hypodigm. The review of morphological systems and the evaluation of the characters used in the literature revealed that there are no diagnostic characters in the anterior portion of the skull and in the molar series of Juliomys, being difficult to differentiate the fossil from the other living species. Only six qualitative characters were variable and applicable to the hypodigm of J. anoblepas. Characters are polymorphic, invariable, or the fossil is not sufficiently complete to determinate its states. The taxon could not be morphometrically differentiated from J. pictipes and J. ossitenuis. Based on the results presented herein, we consider J. anoblepas as a nomen dubium and restrict its name to the taxon’s hypodigm. 

Phenotypical variation and taxonomic correlates of five closely related Andean species of Poa (Poaceae) along geographic and climatic gradients

Phytotaxa ◽  
2014 ◽  
Vol 183 (3) ◽  
pp. 121 ◽  
Author(s):  
Lidia Raquel Scrivanti ◽  
Luciana Mestre ◽  
Ana Maria Anton
Keyword(s):  
Morphological Variation ◽  
Climatic Factors ◽  
Environmental Gradients ◽  
Morphological Characters ◽  
Herbarium Specimens ◽  
Similar Species ◽  
Geographical Distance ◽  
Temperature And Precipitation ◽  
Longitudinal Gradients ◽  
Reproductive Phenotype

Poa anfamensis, P. jujuyensis, P.lilloi, P. parviceps and P. scaberula (Poaceae) are a group of morphologically similar species. These species inhabit cool grasslands and mesic puna. They are highly polymorphic and their circumscriptions are uncertain, especially the entities around P. scaberula. Univariate and multivariate analyses (PCA and DA) were conducted to evaluate the morphological variation among 150 herbarium specimens identified as P. anfamensis, P. jujuyensis, P. lilloi, P. parviceps and P. scaberula. Forty morphological characters were included and their patterns of variation were analyzed among specimens, together with their relationship with environmental variables, using correlation analysis. The relationships between morphological variation and geographical distance, and climatic variables among specimens, were compared with Mantel permutation tests. Taxa were delimited according to the observed clustering of specimens in the PCA plots and DA, and diagnostic characters were identified. The five taxa showed continuous morphological variation. Morphological variation is explained by geographical and climatic factors such as elevation, geographical distance, latitudinal and longitudinal gradients, temperature and precipitation in the different sites in the Andes. Altitudinal and geographical distance are apparently more decisive factors in phenotypic differentiation and could have played a large role in interspecific differentiation among Poa entities, as shown by the stronger and significant association between vegetative and reproductive phenotype and altitudinal distance, and between vegetative and reproductive phenotype and geographical distance. In addition, we observed uncoupling among vegetative and floral characters in Poa specimens that grow along environmental gradients; these characters are responding independently to different abiotic forces promoting genetic divergence and speciation. Based on the results, P. anfamensis and P. parviceps are synonymised with P. scaberula, and P. jujuyensis is synonymised with P. lilloi.

Cytogenetic and sequence comparison of adultPhyllodistomum(Digenea: Gorgoderidae) from the three-spined stickleback with larvae from two bivalves

Parasitology ◽  
2004 ◽  
Vol 129 (6) ◽  
pp. 771-778 ◽  
Author(s):  
R. PETKEVIČIŪTĖ ◽  
V. STUNŽĖNAS ◽  
G. STANEVIČIŪTĖ
Keyword(s):  
Developmental Stages ◽  
Its Region ◽  
Morphological Characters ◽  
Molecular Data ◽  
Chromosome Morphology ◽  
Published Data ◽  
Larval Stages ◽  
Rdna Sequences ◽  
Rdna Sequencing ◽  
High Level

Due to the low informative value of available morphological characters, cytogenetic and molecular methods, based on rDNA sequencing, were used to characterize adult and larval stages ofPhyllodistomumspp. Species studied have 18 chromosomes with comparable absolute and relative lengths. Conventional Giemsa staining and karyometric analysis revealed clear differences in chromosome morphology of larvalPhyllodistomumspp. infecting two bivalve host species,Sphaerium corneumandPisidium amnicum. However, karyotypes of adultP. foliumfrom three-spined sticklebacks and larval stages fromS. corneumappear almost identical both with respect to the relative lengths and centromeric indices of the corresponding chromosome pairs. The entire internal transcribed spacer (ITS) region (ITS-1, 5.8S and ITS-2) and the D1-D3 region of 28S gene were sequenced and compared. Again, sufficient differences were observed between larvalPhyllodistomumspp., while adultP. foliumand larvae fromS. corneumshowed a high level of similarity. So, both cytogenetic and molecular data support the suggestion that they represent developmental stages of the same species. The results were compared with published data obtained by cytogenetic and molecular studies on the otherPhyllodistomumspecies. Differences revealed in karyotype and rDNA sequences leads to the conclusion that the cercariaeum ofP. foliumsensu Sinitsin, 1905 could not be regarded as the larva of adultP. foliumfrom three-spined stickleback.

Chemical and morphological variation within a population of Eucalyptus radiata (Myrtaceae) exhibiting leaf volatile oil chemical forms

1992 ◽  
Vol 5 (1) ◽  
pp. 95 ◽  
Author(s):  
T Whiffin ◽  
A Bouchier
Keyword(s):  
Morphological Variation ◽  
Group Membership ◽  
Volatile Oil ◽  
Morphological Characters ◽  
Chemical Forms ◽  
Fruit Morphology ◽  
Oil Composition ◽  
Flavonoid Composition ◽  
Chemical Groups ◽  
Fruit Characters

Fifty trees were collected from a population of Eucalyptus radiata subsp. radiata known to contain leaf volatile oil chemical forms. These were studied for leaf volatile oil composition, flavonoid composition, and leaf and fruit morphology. Three distinct groups were detected on the basis of leaf volatile oil composition, representing low, medium and high percentages of piperitone, with 43, 3 and 4 plants in each respectively. The low piperitone group contained two subgroups differing in the inversely varying amounts of α-phellandrene and p-cymene. While there was variation in leaf and fruit morphological characters and in flavonoid composition, there was no correlation between any of these characters and the leaf volatile oil chemical groups. Groups could also be distinguished on the basis of morphological characters, especially fruit characters, but these morphological groups were not as distinct as those based on volatile oil characters. There was no association between the morphological groups and the chemical groups on the basis of group membership. The nature and importance of this variation within a Eucalyptus population are discussed.

scholarly journals Morphological variation among fifteen superior robusta coffee clones in Lampung Province, Indonesia

2018 ◽  
Vol 19 (4) ◽  
pp. 1475-1481 ◽  
Author(s):  
SRI RAMADIANA ◽  
DWI HAPSORO ◽  
YUSNITA YUSNITA
Keyword(s):  
Morphological Variation ◽  
Block Design ◽  
Tree Height ◽  
Morphological Characters ◽  
Fruit Shape ◽  
Leaf Length ◽  
Leaf Base ◽  
Ripe Fruit ◽  
Robusta Coffee ◽  
Randomized Complete Block Design

Ramadiana S, Hapsoro D, Yusnita Y. 2018. Morphological variation among fifteen superior robusta coffee clones inLampung Province, Indonesia. Biodiversitas 19: 1475-1481. This study aimed to characterize morphological variation among fifteensuperior robusta coffee clones in Lampung Province. The fifteen clones consisted of four clones released by the Indonesian Coffee andCocoa Research Institute (ICCRI), i.e. ‘BP 409’,‘BP936’, ‘BP939’, ‘SA 237’, together with eleven superior coffee clones selected byfarmers from Tanggamus District (‘Tugino’, ‘Wanto’, ‘Biyadi’, ‘Komari’, ‘Wardi’, ‘Wariso’) and from West Lampung District (‘TuguKuning’, ‘Tugu Hijau', ‘Tugu Biru', ‘Tugu Sari', ‘Lengkong'). Fifteen qualitative and seven quantitative morphological characters wereevaluated in a randomized complete block design with three replicates for each clone,each replication consisted of two plants. Fromeach plant, four samples were taken from four sides of the plant (north, south, west, and east). It was found that while somemorphological characters exhibited negligible variation among clones, there were significant differences between clones for othercharacters. The characters that did not differ significantly between clones were: shapes of leaf base and leaf tip; petiole color; leafvenation pattern; fruit disk shape; ripe-fruit color; and stipule shape. The characters that varied between clones were shape of leaf lamina(elliptical vs. lanceolate); fruit shape (round vs. oval); and shape of leaf margins. Morphological variation was also observed in somequantitative characters: canopy diameter; tree height; stem diameter; leaf length; leaf width; petiole length; stipule length; and number ofprimary branches.

scholarly journals Beyond the carapace: skull shape variation and morphological systematics of long-nosed armadillos (genus Dasypus)

2017 ◽  
Author(s):  
Lionel Hautier ◽  
Guillaume Billet ◽  
Benoit De Thoisy ◽  
Frédéric Delsuc
Keyword(s):  
Morphological Variation ◽  
Distinct Species ◽  
Morphological Characters ◽  
Molecular Data ◽  
Guiana Shield ◽  
Shape Variation ◽  
Skull Morphology ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Shape And Size

Background. The systematics of long-nosed armadillos (genus Dasypus) has been mainly based on a handful of external morphological characters and classical measurements. Here, we studied the pattern of morphological variation in the skull of long-nosed armadillos species, with a focus on the systematics of the widely distributed nine-banded armadillo (D. novemcinctus). Methods. We present the first exhaustive 3D comparison of the skull morphology within the genus Dasypus, based on µCT-scans. We used geometric morphometric approaches to explore the patterns of the intra- and interspecific morphological variation of the skull with regard to several factors such as taxonomy, geography, allometry, and sexual dimorphism. Results. We show that the shape and size of the skull vary greatly between Dasypus species, with D. pilosus representing a clear outlier compared to other long-nosed armadillos. The study of the cranial intraspecific variation in D. novemcinctus evidences clear links to the geographic distribution and argue in favour of a revision of past taxonomic delimitations. Our detailed morphometric comparisons detected previously overlooked morphotypes of nine-banded armadillo, especially a very distinctive unit circumscribed to the Guiana Shield. Discussion. As our results are congruent with recent molecular data and analyses of the structure of paranasal sinuses, we propose that D. novemcinctus should be regarded either as a polytypic species (with three to four subspecies) or as a complex of several distinct species.

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