Morphometric variation within and between populations of the pine aphid, Cinara nigra (Wilson) (Homoptera: Aphidoidea: Lachnidae), in western North America

1990 ◽  
Vol 68 (7) ◽  
pp. 1410-1419 ◽  
Author(s):  
R. G. Foottit ◽  
M. Mackauer
Keyword(s):  
North America ◽  
Morphological Variation ◽  
Pinus Contorta ◽  
Principal Component ◽  
Significant Loss ◽  
Population Variation ◽  
Species Discrimination ◽  
Western North America ◽  
Shape Variation ◽  
Morphometric Variation

Morphological variation in Cinara nigra (Wilson), found on Pinus contorta Dougl. ex Loud, throughout western North America, was characterized with the aid of univariate and multivariate statistical methods. Within-population variation in one sample collected near Edson, Alberta, was examined. Correlation and principal component analysis revealed patterns of interdependence among characters as well as patterns of size and size-related shape variation in 52 characters. To examine morphological variation between 19 geographic samples, this initial set was reduced in two steps to 49 and 32 characters, respectively; the reduction did not result in a significant loss of information content. No geographic pattern in clusters of samples was revealed either by the ordination of sample centroids or by UPGMA cluster analysis of the Mahalanobis D values. The taxonomic implications of this morphometric analysis are discussed, in particular the usefulness of various morphological attributes for species discrimination.

A morphometric study of geographic variation in the snowshoe hare (Lepus americanus)

1985 ◽  
Vol 63 (3) ◽  
pp. 567-579 ◽  
Author(s):  
David W. Nagorsen
Keyword(s):  
North America ◽  
Great Lakes ◽  
Geographic Variation ◽  
Principal Component ◽  
Lepus Americanus ◽  
Morphometric Study ◽  
Western North America ◽  
Environmental Selection ◽  
Local Selection ◽  
Central Canada

Geographic variation in Lepus americanus was studied by multivariate analyses of 15 cranial measurements. A total of 1494 specimens from the entire geographic range were grouped into 37 geographic samples of males and females. Principal component analyses demonstrated that hares are largest in eastern North America, Alaska, and northwestern Canada, and smallest in the Pacific Northwest. Size clines exist in the Appalachian Mountains and western North America but size is relatively uniform throughout central Canada and the Great Lakes. A multiple regression of size with 16 climatic variables factors demonstrated that size and climate are strongly correlated; the size trends may reflect environmental selection. The differentiation of hares from the western Cordillera and Pacific coast, the similarity of populations from central Canada and the Great Lakes, and the clines in the Appalachians and western North America were evident in discriminant analyses. These patterns of variation among populations can be attributed to both gene flow and local selection. There is no evidence from the morphometric analyses for classifying populations into the 15 subspecies currently recognized.

Distribution of the dwarf dog-faced bat Molossops temminckii (Chiroptera: Molossidae) in Colombia and comments on its morphometry

Mammalia ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Julio J. Chacón-Pacheco ◽  
Luis José Avendaño Maldonado ◽  
Carlos Agamez-López ◽  
Ingrith Yuliany Mejía-Fontecha ◽  
Daniela Velásquez-Guarín ◽  
...  
Keyword(s):  
South America ◽  
Morphological Variation ◽  
Principal Component ◽  
The Other ◽  
Cryptic Diversity ◽  
Vocal Plasticity ◽  
Morphometric Variation ◽  
Integrative Analyses ◽  
Principal Component Analyses

AbstractThe genus Molossops includes two species that are restricted to South America: Molossops neglectus and Molossops temminckii. The smaller dog-faced dwarf Molossops temminckii is distributed from Colombia to Argentina and has a wide morphological variation and vocal plasticity. In Colombia, this species remains poorly known. To fill distributional gaps, we present novel records from Arauca, Atlántico, Bolívar, Córdoba, and Huila departments. We also present an analysis of the morphometric variation in South America using Principal Component Analyses. These show an external and cranial difference of specimens of Colombia in respect of other and South America populations. In Colombian landscapes dominated by the floodplain savanna of the Orinoco region, Molossops temminckii is smaller than in the other regions of the country, and the previously suggested existence of cryptic diversity within the taxon should be evaluated. Therefore, we suggest further integrative analyses to investigate a possible subspecific status of some Colombian populations.

Geometric morphometric analysis discriminates native and non-native species of Caprellidae in western North America

2008 ◽  
Vol 89 (3) ◽  
pp. 535-542 ◽  
Author(s):  
Eva I. Riedlecker ◽  
Gail V. Ashton ◽  
Gregory M. Ruiz
Keyword(s):  
North America ◽  
Geometric Morphometrics ◽  
Native Species ◽  
Spline Method ◽  
Western North America ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Geographical Regions ◽  
Geometric Morphometric Analysis ◽  
Caprella Mutica

Characteristics of the second gnathopod are traditionally used to distinguish between species of caprellid amphipods. However, these distinctions are often subjective and can be variable within a species. Geometric morphometrics were used to quantitatively assess shape variation of the second gnathopod propodus of three species of caprellids in North America, including the non-native Caprella mutica. Gnathopod shapes of C. mutica specimens from different latitudes revealed distinct morphologies; the factors responsible for the shape variations are unknown. Allometric change of propodus shape was observed in C. mutica. Larger individuals showed a wide array of possible propodus morphologies. Despite this variability, there were clear differences between large specimens of C. mutica and two species native to North America: C. alaskana and C. kennerlyi. The use of geometric morphometrics and the thin-plate spline method can serve to both complement descriptions using traditional keys and aid in identification of non-native species in novel geographical regions.

scholarly journals Changes toward Earlier Streamflow Timing across Western North America

2005 ◽  
Vol 18 (8) ◽  
pp. 1136-1155 ◽  
Author(s):  
Iris T. Stewart ◽  
Daniel R. Cayan ◽  
Michael D. Dettinger
Keyword(s):  
North America ◽  
Large Scale ◽  
Center Of Mass ◽  
Principal Component ◽  
Warming Trend ◽  
Western North America ◽  
Climate Fluctuations ◽  
Climate Indicators ◽  
Decadal Scale ◽  
Streamflow Timing

Abstract The highly variable timing of streamflow in snowmelt-dominated basins across western North America is an important consequence, and indicator, of climate fluctuations. Changes in the timing of snowmelt-derived streamflow from 1948 to 2002 were investigated in a network of 302 western North America gauges by examining the center of mass for flow, spring pulse onset dates, and seasonal fractional flows through trend and principal component analyses. Statistical analysis of the streamflow timing measures with Pacific climate indicators identified local and key large-scale processes that govern the regionally coherent parts of the changes and their relative importance. Widespread and regionally coherent trends toward earlier onsets of springtime snowmelt and streamflow have taken place across most of western North America, affecting an area that is much larger than previously recognized. These timing changes have resulted in increasing fractions of annual flow occurring earlier in the water year by 1–4 weeks. The immediate (or proximal) forcings for the spatially coherent parts of the year-to-year fluctuations and longer-term trends of streamflow timing have been higher winter and spring temperatures. Although these temperature changes are partly controlled by the decadal-scale Pacific climate mode [Pacific decadal oscillation (PDO)], a separate and significant part of the variance is associated with a springtime warming trend that spans the PDO phases.

Morphological and chromosomal variation in Dodecatheon pulchellum (Primulaceae)

1992 ◽  
Vol 70 (12) ◽  
pp. 2476-2483 ◽  
Author(s):  
Terri A. Suttill ◽  
Geraldine A. Allen
Keyword(s):  
North America ◽  
Morphological Variation ◽  
Genetic Basis ◽  
Common Garden ◽  
Chromosomal Variation ◽  
Western North America ◽  
Chromosome Counts ◽  
Alpine Habitats ◽  
Variable Species ◽  
Ecological Differences

Dodecatheon pulchellum (Raf.) Merr. is a widespread and morphologically variable species of western North America. Analysis of morphological variation, combined with chromosome counts and evidence from a transplant study, showed this species to consist of two subspecies. Subspecies cusickii is pubescent, mainly diploid, and occurs in the drier parts of the species range. The more variable ssp. pulchellum is glabrous to sparsely pubescent, mainly polyploid, and is widely distributed. Within ssp. pulchellum, three varieties can be recognized: the tall, many-flowered var. alaskanum, of wet, low-elevation habitats; the diminutive var. watsonii, generally of alpine habitats; and the intermediate and widely distributed var. pulchellum. Common garden studies indicate that size differences among these varieties have a genetic basis and that ecological differences exist in D. pulchellum even among morphologically similar forms. Key words: Dodecatheon, Primulaceae, systematics, morphology, chromosome numbers, common garden studies.

scholarly journals Identifying planktonic foraminiferal morphospecies: which are the important images?

2021 ◽  
Author(s):  
George H. Scott
Keyword(s):  
Standard Deviation ◽  
Planktonic Foraminifera ◽  
Principal Component ◽  
Population Variation ◽  
Shape Variation ◽  
Equatorial Atlantic ◽  
Accurate Identification ◽  
Reliable Identification ◽  
Pacific Population ◽  
Selection Of

AbstractSelection of imagery that promotes accurate identification of morphotaxa is viewed as a significant problem in the taxonomy of planktonic foraminifera. Currently, imagery of taxa is sparse, apparently selected by visual judgement, and presented without information about its typicality. What is required are impartially selected images which embrace population variation to serve as training sets for reliable identification of taxa. Outlined here is a simple morphometrically-based solution, applied to the shape of shells in two orientations, in which shape variation is resolved onto three principal component axes. On the premise that the best-adapted shells are the commonest, specimens within 1 standard deviation (sd) of the trivariate mean are recognized as population exemplars suitable for use as trainers. Specimens which project at ≥2 sd onto at least one axis are mapped as boundary specimens whose identity might be questioned. This procedure is trialled on samples of Truncorotalia crassaformis. Exemplars from the Equatorial Atlantic and Caribbean compare closely; they partially overlap with those from a Holocene Southwest Pacific population provisionally interpreted as a subtaxon, Truncorotalia crassaformis hessi.

scholarly journals Morphometric variation of Middle-American cichlids: Theraps– Paraneetroplus clade (Actinopterygii: Cichliformes: Cichlidae)

2021 ◽  
Vol 51 (4) ◽  
pp. 403-412
Author(s):  
Yanet Elizabeth Aguilar-Contreras ◽  
Alfonso A. González-Díaz ◽  
Omar Mejía ◽  
Rocío Rodiles-Hernández
Keyword(s):  
Body Shape ◽  
Phylogenetic Signal ◽  
Principal Component ◽  
The Body ◽  
Cranial Morphology ◽  
Group Method ◽  
Morphological Similarity ◽  
Shape Variation ◽  
Morphometric Variation ◽  
Mean Values

This study assesses the patterns of variation in body shape, and relations of morphological similarity among species of the Theraps–Paraneetroplus clade in order to determine whether body shape may be a trait in phylogenetic relations. A total of 208 specimens belonging to 10 species of the Theraps–Paraneetroplus clade were examined. The left side of each specimen was photographed; in each photograph, 27 fixed landmarks were placed to identify patterns in body shape variation. Images were processed by using geometric morphometrics, followed by a phylogenetic principal component analysis. The phylogenetic signal for body shape was then calculated. To determine the relations in morphological similarity, a dendrogram was created using the unweighted pair group method and arithmetic mean values, while a Procrustes ANOVA and post-hoc test were used to evaluate significant differences between species and habitats. We found three morphological groups that differed in body length and depth, head size, and the position of the mouth and eyes. The body shape analysis recovered the morphotypes of seven species, and statistical differences were demonstrated in eight species. Based on traits associated with cranial morphology, Wajpamheros nourissati (Allgayer, 1989) differed the most among the species examined. No phylogenetic signal was found for body shape; this trait shows independence from ancestral relatedness, indicating that there is little congruence between morphological and genetic interspecific patterns. As evidenced by the consistently convergent morphology of the species in the Theraps–Paraneetroplus clade, the diversification of the group is related to an ecological opportunity for habitat use and the exploitation of food resources. Although no phylogenetic signal was detected for body shape, there appears to be an order associated with cranial morphology-based phylogeny. However, it is important to evaluate the intraspecific morphologic plasticity produced by ecological segregation or partitioning of resources. Therefore, future morphological evolutionary studies should consider cranial structures related to the capture and processing of food.

scholarly journals Shell shape variation of queen conch Strombus gigas (Mesograstropoda: Strombidae) from Southwest Caribbean

2016 ◽  
Vol 64 (4) ◽  
Author(s):  
Edna Judith Márquez ◽  
Natalia Restrepo-Escobar ◽  
Francisco Luis Montoya-Herrera
Keyword(s):  
Phenotypic Plasticity ◽  
Geometric Morphometrics ◽  
Genetic Background ◽  
Principal Component ◽  
Caribbean Region ◽  
Shell Shape ◽  
Shape Variation ◽  
Morphometric Variation ◽  
Strombus Gigas

The endangered species Strombus gigas is a marine gastropod of significant economic importance through the Greater Caribbean region. In contrast to phenotypic plasticity, the role of genetics on shell variations in S. gigas has not been addressed so far, despite its importance in evolution, management and conservation of this species. This work used geometric morphometrics to investigate the phenotypic variation of 219 shells of S. gigas from eight sites of the Colombian Southwest Caribbean. Differences in mean size between sexes and among sites were contrasted by analysis of variance. Allometry was tested by multivariate regression and the hypothesis of common slope was contrasted by covariance multivariate analysis. Differences in the shell shape among sites were analyzed by principal component analysis. Sexual size dimorphism was not significant, whereas sexual shape dimorphism was significant and variable across sites. Differences in the shell shape among sites were concordant with genetic differences based on microsatellite data, supporting its genetic background. Besides, differences in the shell shape between populations genetically similar suggest a role of phenotypic plasticity in the morphometric variation of the shell shape. These outcomes evidence the role of genetic background and phenotypic plasticity in the shell shape of S. gigas. Thus, geometric morphometrics of shell shape may constitute a complementary tool to explore the genetic diversity of this species.

Morphometrics and Redescription of Aphyllon fasciculatum and Aphyllon franciscanum, Two Widespread but Previously Conflated Species in Western North America

2021 ◽  
Vol 46 (2) ◽  
pp. 446-455
Author(s):  
Adam C. Schneider ◽  
Ben E. Benton
Keyword(s):  
North America ◽  
Principal Component ◽  
Calyx Lobe ◽  
Corolla Tube ◽  
Herbarium Specimens ◽  
Western North America ◽  
Widespread Species ◽  
Floral Color ◽  
Discriminant Analyses ◽  
Floral Characters

Abstract— We continue the taxonomic reevaluation of Aphyllon sect. Aphyllon by describing a widespread species throughout western North America previously recognized within a polyphyletic A. fasciculatum. To support our description and revised key, we analyzed fifteen continuous and discrete characters sampled from 186 herbarium specimens and iNaturalist observations representing the geographic and host ranges. Principal component and multiple correspondence analyses reveal clear variation in floral characters. Discriminant analyses show that three aspects of floral color, corolla lobe tip shape, the calyx cup to calyx lobe ratio, calyx lobe length, and degree of bend in the corolla tube are useful distinguishing features, but not diagnostic in every case.

Pinus contorta (lodgepole pine).

2021 ◽  
Author(s):  
Ana Jose Cobar
Keyword(s):  
Growth Rate ◽  
North America ◽  
Rapid Growth ◽  
Pinus Contorta ◽  
Stand Development ◽  
Western North America ◽  
Fast Growing ◽  
Ecological Amplitude ◽  
Rapid Growth Rate ◽  
The Usa

Abstract P. contorta is a fast-growing, short-lived and fire-adapted two-needled pine species with a very wide ecological amplitude and tolerance. It is an important and valuable timber trees in western North America, with forests dominated by P. contorta covering some 6 million ha in the USA and 20 million ha in Canada (Burns and Honkala, 1990). Because of its rapid growth rate, small taper and thin bark, it produces a higher volume of wood than many of its associates of the same diameter and height. It is a low nutrient-demanding species and easy to regenerate and grow. A common problem of regenerating P. contorta is overstocking which may result in growth stagnation during early stand development on water-deficient, nutrient-poor sites.

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