scholarly journals The First Insight into the Patterns of Size and Shape Variation of a Microcerberid Isopod

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 515
Author(s):  
Jeongho Kim ◽  
Jaehyun Kim ◽  
Wonchoel Lee ◽  
Ivana Karanovic
Keyword(s):  
Cryptic Species ◽  
Size Variation ◽  
Shape Variation ◽  
Morphological Pattern ◽  
Size And Shape ◽  
Taxonomic Methods ◽  
Morphological Differences ◽  
High Degree ◽  
Insight Into ◽  
Genetic Species

Cryptic species are a biological phenomenon only recently recognized due to progress in molecular studies. They pose a significant challenge to conventional taxonomic work since these species manifest low morphological differences, but considerable genetic disparity. New taxonomic methods are in development but have yet to be tested for many animal groups. Isopods belonging to the suborder Microcerberidea are one such group. The Asian microcerberid isopod, Coxicerberus fukudai (Ito, 1974), is a major component of marine interstitial fauna with suspected cryptic species inhabiting Japan and Korea. We chose six Korean populations with high molecular interpopulations divergence and applied 2D landmark-based geometric morphometrics to cephalic sensilla, pleonal points, and male pleopod II. This quantitative approach allowed us to study interpopulation size and shape variations, morphospace structure, and whether the morphological pattern mirrored the genetic species. We determined that a high degree of interpopulation size variation significantly influences shape changes. Once we removed the allometric effect, the size-corrected male pleopod II shape variations yielded a new species, C. jangsaensis sp. nov. At the same time, we were able to resolve the C. fukadai species complex.

scholarly journals Size and shape variation in the calcareous nannoplankton genus Braarudosphaera following the Cretaceous/Paleogene (K/Pg) mass extinction: clues as to its evolutionary success

Paleobiology ◽  
2021 ◽  
pp. 1-24
Author(s):  
Heather L. Jones ◽  
Zachary Scrobola ◽  
Timothy J. Bralower
Keyword(s):  
Cryptic Species ◽  
Mass Extinction ◽  
Evolutionary History ◽  
Late Triassic ◽  
Shape Variation ◽  
Calcareous Nannoplankton ◽  
Size And Shape ◽  
Water Column Stratification ◽  
Early Paleocene ◽  
Tethys Ocean

Abstract Calcareous nannoplankton have been one of the dominant primary producers in the surface oceans since the late Triassic. The bolide impact at the Cretaceous/Paleogene (K/Pg) boundary ~66.0 Ma, led to the elimination of >90% of nannoplankton species: the largest extinction event in their evolutionary history. One of the few nannoplankton genera to survive the K/Pg mass extinction and even thrive in its aftermath was Braarudosphaera, which precipitates pentagonal calcite plates (pentaliths). The only Braarudosphaera species to span the K/Pg boundary (B. bigelowii) is extant and has formed geographically and temporally restricted “blooms” throughout geologic time. Four morphologically and genetically distinct cryptic species of B. bigelowii have been identified in the modern ocean. However, it is uncertain whether these cryptic species have disparate ecophysiological tolerances that have allowed them to adapt to varying environmental conditions. For the first time, we assess changes in the size and shape of Braarudosphaera pentaliths following the K/Pg mass extinction at three geographically and environmentally disparate sites that have early Paleocene Braarudosphaera blooms. Our results show that different Braarudosphaera morphotypes were dominant in the Gulf of Mexico compared with the Tethys Ocean, likely due to regional environmental differences. In addition, we provide evidence that the dominant Braarudosphaera morphotypes shifted in response to changes in upper water column stratification. This ability to rapidly adapt to unstable environments likely helped Braarudosphaera thrive in the aftermath of the K/Pg extinction and explains why this lineage has enjoyed such a long evolutionary history.

Averaging v. outlier removal. Decrypting variance among cryptic Lejeunea species (Lejeuneaceae: Jungermanniopsida) using geometric morphometrics

2013 ◽  
Vol 26 (1) ◽  
pp. 13 ◽  
Author(s):  
Matt A. M. Renner ◽  
Elizabeth A. Brown ◽  
Glenda M. Wardle
Keyword(s):  
Cryptic Species ◽  
Individual Variation ◽  
Species Difference ◽  
Molecular Data ◽  
Species Variation ◽  
Shape Variation ◽  
Outlier Removal ◽  
Geometric Morphometric ◽  
Size And Shape ◽  
Developmental Capacity

Molecular data have revealed many morphologically cryptic species. More surprising than lack of difference, however, is that morphological variation and complex patterns of overlapping features can mask cryptic species. We employ geometric morphometric methods (GMM) to explore patterns of variation within four liverwort species, three of which were previously attributed to Lejeunea tumida Mitt. Each species exhibited considerable variation within, and overlap among, species in size and shape, independent of degree of relatedness. Most variation was expressed within individuals, suggesting that the observed breadth of variation was within the developmental capacity of single genotypes. Size and shape variation within, and consequently overlap among, individuals resulted primarily from variance in growth of shoots. Inter-specific differences were swamped by intra- and inter-individual variation. We coupled GMM with multivariate methods for outlier removal, and simple averaging of individuals to explore whether intra-individual variation could be reconciled to maximise the inter-species difference, facilitating resolution of cryptic species despite extensive morphological continuity and overlap. Unfortunately, outlier removal did not achieve separation among species, because removing extremes failed to eliminate overlap resulting from within-species variation. Individual averaging was partially successful in extracting L. tumida as a discrete entity but did not segregate the remaining three species. Although the challenges for morphology-based identification of cryptic species are significant, GMM provide one of the best sets of methods for identifying and communicating any subtle morphological differences that may exist.

scholarly journals The Bostrychia tenella species complex: Morphospecies and genetic cryptic species with resurrection of B. binderi

2021 ◽  
Author(s):  
Giuseppe Zuccarello ◽  
N Muangmai ◽  
Maren Preuss ◽  
LB Sanchez ◽  
SL De Göer ◽  
...  
Keyword(s):  
Cryptic Species ◽  
Morphological Variation ◽  
Species Complex ◽  
Type Specimen ◽  
Molecular Data ◽  
Molecular Evidence ◽  
Variable Species ◽  
Morphological Differences ◽  
Multiple Species ◽  
Genetic Species

© 2015 International Phycological Society. The question of whether morphological differences observed in specimens is due to multiple species or one variable species has always caused problems for taxonomists. The most recent taxonomic treatment of the 'Bostrychia tenella species complex' suggested that much of the morphological variation represented a single highly variable entity. We used molecular data from all three genomes to clarify the phylogeny, species status and phylogeography of samples collected worldwide and also in sympatry of this complex. Our data strongly support five genetic species in this complex, but only three morphological entities were recognized. The first, divided into two genetic species, fits characters associated with B. binderi, occasionally possessing short monosiphonous determinate laterals but lacking them most of the time. We therefore resurrect B. binderi, even though we could not assign a name to either of the two genetic species, as we are missing molecular evidence from the type specimen. One genetic species was morphologically recognized as B. montagnei. Another lineage consisted of the two genetic species that fall into a new circumscription of B. tenella, with long monosiphonous determinate laterals. Again we were unable to assign either of these two lineages to a type, nor could we find morphological differences between the two lineages. Many of the genetic species have worldwide distributions, except for B. montagnei, which appears to be restricted to the Americas. Our molecular-assisted taxonomy has helped clarify some of the morphological variation within the B. tenella species complex into three named species, but two cryptic species were still recognized that remain morphologically cryptic. This is an Accepted Manuscript of an article published by Taylor & Francis in 'Phycologia' on 2015-05-01, available online: https://www.tandfonline.com/10.2216/15-005.1.

scholarly journals The Bostrychia tenella species complex: Morphospecies and genetic cryptic species with resurrection of B. binderi

2021 ◽  
Author(s):  
Giuseppe Zuccarello ◽  
N Muangmai ◽  
Maren Preuss ◽  
LB Sanchez ◽  
SL De Göer ◽  
...  
Keyword(s):  
Cryptic Species ◽  
Morphological Variation ◽  
Species Complex ◽  
Type Specimen ◽  
Molecular Data ◽  
Molecular Evidence ◽  
Variable Species ◽  
Morphological Differences ◽  
Multiple Species ◽  
Genetic Species

© 2015 International Phycological Society. The question of whether morphological differences observed in specimens is due to multiple species or one variable species has always caused problems for taxonomists. The most recent taxonomic treatment of the 'Bostrychia tenella species complex' suggested that much of the morphological variation represented a single highly variable entity. We used molecular data from all three genomes to clarify the phylogeny, species status and phylogeography of samples collected worldwide and also in sympatry of this complex. Our data strongly support five genetic species in this complex, but only three morphological entities were recognized. The first, divided into two genetic species, fits characters associated with B. binderi, occasionally possessing short monosiphonous determinate laterals but lacking them most of the time. We therefore resurrect B. binderi, even though we could not assign a name to either of the two genetic species, as we are missing molecular evidence from the type specimen. One genetic species was morphologically recognized as B. montagnei. Another lineage consisted of the two genetic species that fall into a new circumscription of B. tenella, with long monosiphonous determinate laterals. Again we were unable to assign either of these two lineages to a type, nor could we find morphological differences between the two lineages. Many of the genetic species have worldwide distributions, except for B. montagnei, which appears to be restricted to the Americas. Our molecular-assisted taxonomy has helped clarify some of the morphological variation within the B. tenella species complex into three named species, but two cryptic species were still recognized that remain morphologically cryptic. This is an Accepted Manuscript of an article published by Taylor & Francis in 'Phycologia' on 2015-05-01, available online: https://www.tandfonline.com/10.2216/15-005.1.

scholarly journals Size and shape in Melipona quadrifasciata anthidioides Lepeletier, 1836 (Hymenoptera; Meliponini)

2013 ◽  
Vol 73 (4) ◽  
pp. 887-893 ◽  
Author(s):  
LA Nunes ◽  
GB Passos ◽  
CAL Carvalho ◽  
ED Araújo
Keyword(s):  
Size Variation ◽  
Mantel Test ◽  
Evolutionary Constraints ◽  
Partial Mantel Test ◽  
Wing Size ◽  
Shape Variation ◽  
Size And Shape ◽  
Melipona Quadrifasciata ◽  
Semi Arid Region ◽  
Shape And Size

This study aimed to identify differences in wing shape among populations of Melipona quadrifasciata anthidioides obtained in 23 locations in the semi-arid region of Bahia state (Brazil). Analysis of the Procrustes distances among mean wing shapes indicated that population structure did not determine shape variation. Instead, populations were structured geographically according to wing size. The Partial Mantel Test between morphometric (shape and size) distance matrices and altitude, taking geographic distances into account, was used for a more detailed understanding of size and shape determinants. A partial Mantel test between morphometris (shape and size) variation and altitude, taking geographic distances into account, revealed that size (but not shape) is largely influenced by altitude (r = 0.54 p < 0.01). These results indicate greater evolutionary constraints for the shape variation, which must be directly associated with aerodynamic issues in this structure. The size, however, indicates that the bees tend to have larger wings in populations located at higher altitudes.

scholarly journals Genetic and environmental correlates of morphological variation in a marine fish: the case of Baltic Sea herring (Clupea harengus)

2008 ◽  
Vol 65 (3) ◽  
pp. 389-400 ◽  
Author(s):  
Hanne B.H. Jørgensen ◽  
Cino Pertoldi ◽  
Michael M Hansen ◽  
Daniel E Ruzzante ◽  
Volker Loeschcke
Keyword(s):  
Baltic Sea ◽  
Morphological Variation ◽  
Size Variation ◽  
Clupea Harengus ◽  
Shape Variation ◽  
Skull Shape ◽  
Environmental Correlates ◽  
Fin Rays ◽  
Morphological Differences ◽  
The Baltic

Baltic Sea herring (Clupea harengus) have been shown to exhibit morphological differences across the marked salinity and temperature gradients in the region. Here we analyse genetic (nine microsatellite loci), morpho metric (skull shape), and meristic (pectoral fin rays and number of vertebrae) variations across seven samples of spawning herring collected from four spawning locations in the Baltic Sea to examine whether morphological variation correlates with genetic and (or) environmental factors. Results suggest that herring is adapting to its environment through a combination of selection and plastic responses. Skull shape, including and excluding size variation, differed significantly among samples, both temporally and spatially. Genetic and morphometric distances were correlated, especially when size variation was excluded from the analysis. When size variation was included, skull shape variation was more closely correlated with environmental distances among spawning locations. Vertebrate number differed among samples and was correlated with environmental distances, whereas the number of fin rays was not. Genetic and geographic distances among samples were not correlated.

scholarly journals Variation of the Three-Dimensional Femoral J-Curve in the Native Knee

2021 ◽  
Vol 11 (7) ◽  
pp. 592
Author(s):  
Sonja A. G. A. Grothues ◽  
Klaus Radermacher
Keyword(s):  
Geometric Parameter ◽  
Knee Kinematics ◽  
Size Variation ◽  
Principal Component ◽  
Parameter Analysis ◽  
Patient Specific ◽  
3D Analysis ◽  
Relative Location ◽  
Shape Variation ◽  
J Curve

The native femoral J-Curve is known to be a relevant determinant of knee biomechanics. Similarly, after total knee arthroplasty, the J-Curve of the femoral implant component is reported to have a high impact on knee kinematics. The shape of the native femoral J-Curve has previously been analyzed in 2D, however, the knee motion is not planar. In this study, we investigated the J-Curve in 3D by principal component analysis (PCA) and the resulting mean shapes and modes by geometric parameter analysis. Surface models of 90 cadaveric femora were available, 56 male, 32 female and two without respective information. After the translation to a bone-specific coordinate system, relevant contours of the femoral condyles were derived using virtual rotating cutting planes. For each derived contour, an extremum search was performed. The extremum points were used to define the 3D J-Curve of each condyle. Afterwards a PCA and a geometric parameter analysis were performed on the medial and lateral 3D J-Curves. The normalized measures of the mean shapes and the aspects of shape variation of the male and female 3D J-Curves were found to be similar. When considering both female and male J-Curves in a combined analysis, the first mode of the PCA primarily consisted of changes in size, highlighting size differences between female and male femora. Apart from changes in size, variation regarding aspect ratio, arc lengths, orientation, circularity, as well as regarding relative location of the 3D J-Curves was found. The results of this study are in agreement with those of previous 2D analyses on shape and shape variation of the femoral J-Curves. The presented 3D analysis highlights new aspects of shape variability, e.g., regarding curvature and relative location in the transversal plane. Finally, the analysis presented may support the design of (patient-specific) femoral implant components for TKA.

AN ANALYSIS OF INTERSPECIFIC AND INTRASPECIFIC MORPHOLOGICAL DIFFERENCES IN TWO CLOSELY RELATED SPECIES OF AMBLYSEIUS BERLESE USING METHODS OF NUMERICAL TAXONOMY (ACARINA: PHYTOSEHDAE)

1977 ◽  
Vol 109 (12) ◽  
pp. 1605-1618 ◽  
Author(s):  
D.A. Chant ◽  
R.I.C. Hansell ◽  
H.J. Rowell
Keyword(s):  
Host Plant ◽  
Morphological Variation ◽  
Related Species ◽  
Numerical Taxonomy ◽  
Valid Species ◽  
Closely Related Species ◽  
Multivariate Tests ◽  
Taxonomic Methods ◽  
Morphological Differences ◽  
Intraspecific Morphological Variation

AbstractMorphological variation between two closely related species in the genus Amblyseius Berlese was examined by numerical taxonomic methods. Multivariate tests indicated that A. canadensis Chant and Hansell and A. novaescotiae (Chant) represent two separate and distinct morphological groups. This supports their taxonomic retention as valid species. Intraspecific morphological variation was also examined and found to be correlated with climatic and host plant variables.

Oil Companies and Climate Change: Inconsistencies between Strategy Formulation and Implementation?

2007 ◽  
Vol 7 (3) ◽  
pp. 42-62 ◽  
Author(s):  
Ingvild Andreassen Sæverud ◽  
Jon Birger Skjærseth
Keyword(s):  
Climate Change ◽  
Strategy Formulation ◽  
Oil Companies ◽  
Corporate Strategies ◽  
International Climate ◽  
Framework Conditions ◽  
High Degree ◽  
The Relationship ◽  
Level 2 ◽  
Insight Into

This article examines major oil companies in terms of climate strategies and their implementation. More specifıcally, it takes a critical look at Shell, BP, and ExxonMobil, and the relationship between rhetoric and action regarding investments in climate-friendly activities. Empirical evidence indicates a generally high degree of consistency between what these companies say and what they do, but interesting differences are also found: ExxonMobil has done somewhat more than its climate strategy formulations would suggest; Shell has done somewhat less; whereas BP's activities are mainly in line with its statements. Factors at three levels contribute to explaining these differences: (1) the company level, 2) the political framework conditions in the various regions where the companies operate, 3) international climate cooperation. The fındings and explanations, although restricted to the three oil companies with regard to climate change, provide insight into the relationship between corporate strategies and implementation more generally. They offer understanding and analytical categories for assessing how well and why such multinational entities put into practice stated objectives.

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