Delimiting species boundaries within the Bothriochloa saccharoides complex (Poaceae) through morphometric analysis

Phytotaxa ◽  
2013 ◽  
Vol 89 (1) ◽  
pp. 24
Author(s):  
LIDIA R. SCRIVANTI ◽  
GUILLERMO A. NORRMANN ◽  
ANA M. ANTON
Keyword(s):  
Discriminant Analysis ◽  
Morphometric Analysis ◽  
Principal Components ◽  
Morphological Variation ◽  
Species Complex ◽  
Morphological Characters ◽  
Chemical Data ◽  
Species Boundaries ◽  
Herbarium Specimens ◽  
Components Analysis

The Bothriochloa saccharoides complex is one of the most interesting groups within the genus Bothriochloa (Poaceae). The plants inhabit grasslands of tropical and subtropical regions from the Americas. Principal components analysis (PCA) and discriminant analysis (DA) were employed to evaluate the morphological variation among 60 herbarium specimens tentatively identified as B. imperatoides, B. laguroides, B. longipaniculata, B. saccharoides and B. torreyana. Twenty-three morphological characters were included in the analysis in order to clarify problematic species boundaries. Chemical data was incorporated to improve the resolution on delimitation of the species complex. Taxa were delimited according to the observed clustering of specimens in the PCA plots and discriminant analysis, and diagnostic characters were identified. The results showed that five taxa could be distinguished on the basis of morphological characters and chemical data. Two new subspecies are described: B. saccharoides subsp. americana and B. saccharoides subsp. australis. An identification key and a taxonomic synopsis are provided.

Revision of the Calceolaria tripartita s. l. species complex (Calceolariaceae) using multivariate analyses of morphological characters

Phytotaxa ◽  
2014 ◽  
Vol 167 (1) ◽  
pp. 61
Author(s):  
PAMELA PUPPO
Keyword(s):  
Morphological Variation ◽  
Species Complex ◽  
Population Level ◽  
Morphological Characters ◽  
Herbarium Specimens ◽  
Key To Species ◽  
Quantitative Characters ◽  
Components Analysis ◽  
Morphological Differences ◽  
Floral Characters

The morphological variation of the Calceolaria tripartita species complex was evaluated using Principal Components Analysis (PCA) of morphological characters. Fourteen quantitative characters were measured on more than 250 herbarium specimens. The results suggest the recognition of three entities based on floral characters, especially stamen morphology. The distinction between C. mandoniana, C. chelidonioides and C. tripartita s.s. is not supported. The morphological differences between the closely related C. tripartita s.s. and C. chelidonioides were also analyzed using two characters previously used to differentiate them. Finally, the morphological variation of C. tripartita s.s. throughout its geographical range and at an intra-population level was also surveyed. Even though this species is highly variable, no further subdivision is supported morphologically. A taxonomic synopsis and a key to species of the Calceolaria tripartita species complex are provided.

scholarly journals The taxonomic status of Tilia dasystyla in Crimea, Ukraine

1999 ◽  
Vol 56 (2) ◽  
pp. 161-173 ◽  
Author(s):  
C. D. Pigott ◽  
B. Francis
Keyword(s):  
Logistic Regression ◽  
Principal Components ◽  
Taxonomic Status ◽  
Single Species ◽  
Morphological Characters ◽  
Herbarium Specimens ◽  
Chromosome Counts ◽  
The Caucasus ◽  
Fresh Material ◽  
Components Analysis

Nine populations of Tilia dasystyla Steven (Tiliaceae) in the Crimean mountains (Krymskiye Gory), including the type locality at Kastel Dag, were studied in the field and sampled by collection of herbarium specimens. This material was compared with specimens referred to Tilia hegonifolia Steven collected in Crimea, the Caucasus and Iran. Measurements or scores of 21 morphological characters made on the dried material were analysed by principal components analysis and logistic regression. These analyses demonstrated that the majority of trees could be correctly allocated to either Crimea or the Caucasus and Iran on the basis of the shape of their leaves and the area of their bracts. In addition there are differences of leaf and bract texture and bract colour which can be observed in fresh material. Chromosome counts showed that Crimean trees and one Caucasian tree are tetraploid (2n = 164). It is proposed that the Crimean, Caucasian and Iranian trees be treated as a single species with at least two subspecies: Tilia dasystyla Steven subsp. dasystyla from Crimea and T. dasystyla Steven subsp. caucasica (V. Engl.) Pigott from the Caucasus and Iran.

Morphological variation in relation to the taxonomy of the destructor group of the genus Cherax

1988 ◽  
Vol 2 (1) ◽  
pp. 55 ◽  
Author(s):  
A Sokol
Keyword(s):  
Principal Components Analysis ◽  
Principal Components ◽  
Morphological Variation ◽  
Analysis Of Covariance ◽  
Bivariate Analysis ◽  
Morphological Divergence ◽  
Analysis Techniques ◽  
Late Tertiary ◽  
Outgroup Species ◽  
Components Analysis

The present study was directed at clarifying the taxonomy of the destructor group of the genus Cherax. This group was defined by Riek (1969) to include four species: C. destructor Clark, C. albidus Clark, C. davisi Clark and C. esculus Riek. Approximately 1600 specimens representing over 80 localities were examined, including specimens from three outgroup species; C. rotundus, C. punctatus and C. dispar. Variation in 16 metric and 30 multistate characters was analysed by bivariate (analysis of covariance) and multivariate (principal components analysis) techniques. None of the taxonomic analyses supported the distinction of C. davisi or C. esculus from C. destructor, which suggests that the two former species be synonymised with the last. By contrast, C. albidus was found to be morphologically distinct. The pattern and timing of speciation of C. albidus and C. destructor are unclear but may relate to the increase in aridity in inland Australia during the late Tertiary. The analyses also indicated that heterochrony may underly the morphological divergence of these two species.

Amphibian Distribution with Respect to Pond Water Chemistry near Sudbury, Ontario

1992 ◽  
Vol 49 (S1) ◽  
pp. 114-121 ◽  
Author(s):  
V. Glooschenko ◽  
W. F. Weller ◽  
P. G. R. Smith ◽  
R. Alvo ◽  
J. H. G. Archbold
Keyword(s):  
Discriminant Analysis ◽  
Water Chemistry ◽  
Principal Components ◽  
Rana Sylvatica ◽  
Pond Water ◽  
Bufo Americanus ◽  
Breeding Sites ◽  
Metal Levels ◽  
Components Analysis ◽  
Detailed Chemical

Amphibians were present in 118 potential breeding sites 9–66 km northeast and southwest of Sudbury, Ontario. Detailed chemical analyses were done for 38 ponds, and 23 variables were subjected to principal components analysis to summarize the main gradients in pond chemistry. Discriminant analysis using scores of the first three principal components showed that the presence of Rana pipiens, R. clamitans and Hyla crucifer was positively related to buffering status (alkalinity, pH, and other correlated variables); the presence of H. crucifer was also negatively related to atmospheric deposition status (cadmium, nickel, other correlated metals, and sulphate). Discriminant analysis using the original water chemistry variables confirms these general patterns. Two species show relationships with buffering status variables: Rana sylvatica with conductivity and R. clamitans with alkalinity. Three species also show negative correlation with metal levels in pond water: Bufo americanus with nickel, R. clamitans with aluminum, and R. pipiens with zinc. Although most of the species expected do occur in the Sudbury area, the distributions of several species appear related to buffering status and metals present in their immediate environemnt. There were only two observations of Ambystoma maculatum, and low numbers of egg masses were noted for R. sylvatica.

A re-evaluation of species limits in Canadian Arctic Island Puccinellia (Poaceae): resolving key characters

2001 ◽  
Vol 79 (8) ◽  
pp. 927-956 ◽  
Author(s):  
L L Consaul ◽  
L J Gillespie
Keyword(s):  
Principal Components ◽  
Canadian Arctic ◽  
Small Degree ◽  
Species Boundaries ◽  
Key To Species ◽  
Species Complexes ◽  
Morphometric Analyses ◽  
Species Groups ◽  
Components Analysis ◽  
Variation Explained

This study examined morphological variation for species of Puccinellia that have traditionally posed problems of identification in the Canadian Arctic Archipelago. The first part of the study involved a re-examination of several characters that were difficult to define or describe. Microscopic examination of lemma and glume apices revealed that the characters "erose-ciliolate" lemma and glume apex margins are more accurately divided into two characters: degree to which they are erose, and presence of trichomes. These trichomes consist of acute or acuminate cells that protrude 15–35 µm from the margin, sometimes with a spinulose tip up to 10 µm long. The term "thickened pedicel" is clarified to mean thickened below the apex in relation to the apex. The second part of the study involved preliminary morphometric analyses on the above-mentioned revised characters, plus other characters previously shown to have low plasticity in this genus, for 10 recognized species that are difficult to distinguish. Many species or species complexes resolved to a small degree, but no taxa formed distinct groups. Correlations among many characters were low, accounting for a low percentage of variation explained by the first few principal components. Hypotheses of species boundaries and a preliminary revised key to species and species groups, incorporating findings from this study, are presented.Key words: Puccinellia, Canadian Arctic, morphology, trichomes, principal components analysis, cluster analysis.

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.

Morphological Variation in the Dentition and Skull of the Australian Ghost Bat, Macroderma-Gigas (Microchiroptera, Megadermatidae)

1990 ◽  
Vol 38 (3) ◽  
pp. 263 ◽  
Author(s):  
S Hand ◽  
A York
Keyword(s):  
Principal Components Analysis ◽  
Principal Components ◽  
Morphological Variation ◽  
Univariate Analysis ◽  
South Australia ◽  
Clinal Variation ◽  
Clear Cut ◽  
Cranial Measurements ◽  
Southern Central ◽  
Components Analysis

Morphological variation in the dentition and some cranial characters of the Australian ghost bat, Macroderma gigas, is reviewed by means of univariate and multivariate analyses. Specimens examined are drawn from existing populations across northern Australia; also included for parts of this study are mummified remains from southern central South Australia and late Pleistocene subfossil specimens from south-western Western Australia. No clear-cut geographic pattern in morphological variation in M. gigas is indicated by multivariate anlysis (i.e. principal components analysis), although there is some evidence for clinal variation from univariate analysis (i.e. Scheffe's multiple-comparions procedure). Northern Australian ghost bats (with the exception of north-eastern Australian indiv~duals) tend to be smaller than their southern counterparts. Sexual dimorphism appears to be low. Independent patterns of covariation among characters are extracted by principal components analysis: cheek tooth widths cluster separately from lengths; lengths and widths of the same teeth cluster separately from those of occluding teeth; and cranial measurements cluster separately from tooth measurements. Patterns in the data suggest that the number of characters needed to be examined in future morphometric studies of the vulnerable ghost bat can be significantly reduced.

scholarly journals Implications of measurement error structure on the visualization of multivariate chemical data: hazards and alternatives

2018 ◽  
Vol 96 (7) ◽  
pp. 738-748 ◽  
Author(s):  
Peter D. Wentzell ◽  
Chelsi C. Wicks ◽  
Jez W.B. Braga ◽  
Liz F. Soares ◽  
Tereza C.M. Pastore ◽  
...  
Keyword(s):  
Data Analysis ◽  
Measurement Error ◽  
Principal Components Analysis ◽  
Principal Components ◽  
Measurement Errors ◽  
Alternative Methods ◽  
Chemical Data ◽  
Multidimensional Data ◽  
Chemical Information ◽  
Components Analysis

The analysis of multivariate chemical data is commonplace in fields ranging from metabolomics to forensic classification. Many of these studies rely on exploratory visualization methods that represent the multidimensional data in spaces of lower dimensionality, such as hierarchical cluster analysis (HCA) or principal components analysis (PCA). However, such methods rely on assumptions of independent measurement errors with uniform variance and can fail to reveal important information when these assumptions are violated, as they often are for chemical data. This work demonstrates how two alternative methods, maximum likelihood principal components analysis (MLPCA) and projection pursuit analysis (PPA), can reveal chemical information hidden from more traditional techniques. Experimental data to compare different methods consists of near-infrared (NIR) reflectance spectra from 108 samples of wood that are derived from four different species of Brazilian trees. The measurement error characteristics of the spectra are examined and it is shown that, by incorporating measurement error information into the data analysis (through MLPCA) or using alternative projection criteria (i.e., PPA), samples can be separated by species. These techniques are proposed as powerful tools for multivariate data analysis in chemistry.

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