A morphometric assessment of geographical variation and subspecies in impala

The single species of Aepyceros, Aepyceros melampus (impala), is native to central and southern Africa, from Uganda to South Africa. It inhabits open woodlands, sandy bush country and acacia savannah. This study tested the morphological and geographical variation among specimens of impala and their possible relation with described subspecies. Nineteen skull and horn measurements were taken. A multivariate analysis was used and size and shape were explored. Facial coat patterns were also coded. The results supported four out of five traditionally described subspecies: Aepyceros melampus petersi from Angola/Namibia, Aepyceros melampus melampus from South Africa, Aepyceros melampus suara from East Africa and Aepyceros melampus johnstoni from Zambia and Malawi. We consider Aepyceros melampus rendilis to be a synonym of suara . A revised synopsis is suggested, with comments on the geographical ranges of the subspecies. Skull dimensions also allowed us to estimate the geographical origin and subspecies of some individuals of unknown provenance. Coat patterns showed no clear relation with subspecies or geographic location, with the exception of A. m. petersi .     

Computational geometry assessment for morphometric analysis of the mandible

This paper presents a fully automated algorithm for geometry assessment of the mandible. Anatomical landmarks could be reliably detected and distances were statistically evaluated with principal component analysis. The method allows for the first time to generate a mean mandible shape with statistically valid geometrical variations based on a large set of 497 CT-scans of human mandibles. The data may be used in bioengineering for designing novel oral implants, for planning of computer-guided surgery, and for the improvement of biomechanical models, as it is shown that commercially available mandible replicas differ significantly from the mean of the investigated population.     

Geometric morphometric assessment of sexually dimorphic characteristics of the distal humerus

A number of recent studies investigated the use of morphological characteristics of the distal humerus to estimate the sex of unknown individuals. Using visual assessment, accuracies ranging from 74% to more than 90% were reported. The aim of this study was to assess these traits with geometric morphometrics, in order to determine if they corroborate the findings described with pure visual assessment. A total sample of 155 female and 175 male humeri of South Africans were used. All humeri were photographed in standardized positions from a posterior and inferior view, and homologous landmarks assigned. Olecranon fossa shape, angle of the medial epicondyle and trochlear symmetry were assessed. Males and females could be separated with accuracies ranging from 78% to 91%. The results of this study confirm the existence of these traits and their usability in assessment of sex from skeletal remains, and the observed anatomical characteristics largely agree with what have been described by visual assessment.     

Cultural learning and the Clovis colonization of North America

The timing of the earliest colonization of North America is debatable, but what is not at issue is the point of origin of the early colonists: Humans entered the continent from Beringia and then made their way south along or near the Pacific Coast and/or through a corridor that ran between the Cordilleran and Laurentide ice sheets in western North America. At some point, they abandoned their Arctic‐based tool complex for one more adapted to an entirely different environment. That new techno‐complex is termed “Clovis”; its dispersal allows us to examine, at a fine scale, how colonization processes played out across a vast continent that at the time had, at best, a very small resident population. Clovis has figured prominently in American archeology since the first Clovis points were identified in eastern New Mexico in the 1930s. However, the successful marriage of learning models grounded in evolutionary theory and modern analytical methods that began roughly a decade ago has begun to pay significant dividends in terms of what we know about the rapid spread of human groups across the last sizable landmass to witness human occupation.     

A geometric morphometric assessment of the effects of environment and cladogenesis on the evolution of the turtle shell

In the largest group of extant turtles, the Testudinoidea, the acquisition of an aquatic or terrestrial way of life has occurred within two clades, allowing the study of homoplasy linked to environment (commonly named convergence). Here we appraise the respective importance of two sources of morphological variation: a major cladogenetic event and a major environmental shift (aquatic vs. terrestrial). The repeatability of the same evolutionary process (environmental change) allows an assessment of the weights of both natural selection and phylogenetic constraints on several morphological features of the shell. These sources of morphological variance on the complex shell structure were studied using geometric morphometrics. We depict the morphological variation of three parts of the turtle shell: epidermal carapace, bony carapace, and plastron. In the three structures, we found that both phylogeny and environment were significant sources of morphological variation, and geometric morphometrics allowed the pattern of morphological variation due to each effect to be assessed. The assessment of the homoplasy due to environment and of the pattern of morphological variability suggests that the carapace has undergone similar morphological changes between aquatic and terrestrial environments within the two clades. The radiation of the Testudinoidea is interpreted as an adaptive radiation.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 485–501.     

Cytomorphologic and morphometric limitations of the assessment of atypia in fibroadenoma of the breast

OBJECTIVE: To investigate the relevance of nuclear morphometry in separating the categories of "fibroadenoma" and "fibroadenoma with atypia." STUDY DESIGN: Thirty consecutive breast lumps, on which a fine needle aspiration (FNA) diagnosis of fibroadenoma was followed by excision and histopathologic confirmation of the diagnosis, were included. Atypia on cytology was based on cell overlap, nuclear enlargement and cell dyscohesion. Nuclear morphometric comparison was carried out between the categories of fibroadenoma, fibroadenoma with atypia and grade 1 ductal carcinoma cases that formed part of an earlier study. The parameters employed were area, roundness, diameter, perimeter and grey level. RESULTS: Among the 30 cases of fibroadenoma reported on FNA, an additional component of atypia was noted in 5. On subsequent histopathology, atypia was not confirmed in any of the cases. On morphometric analysis, a significant difference was noted between fibroadenoma and fibroadenoma with atypia categories, as between fibroadenoma and grade 1 ductal carcinoma cases. However, no significant difference was noted between fibroadenoma with atypia and grade 1 ductal carcinoma cases. CONCLUSION: FNA assessment of atypia in cases of fibroadenoma is difficult. Even conventional nuclear morphometry, though supporting the initial impression of atypia, does not help with this assessment. Also, based on morphometry alone, there may be difficulty separating fibroadenomas with atypia and grade 1 ductal carcinomas. Larger studies, employing other morphometric parameters, such as chromatin texture and fractal dimension, may shed further light on the subject.     

Investigation into the usability of geometric morphometric analysis in assessment of sexual dimorphism

Understanding sexual dimorphism is very important in studies of human evolution and skeletal biology. Sexual dimorphic characteristics can be studied morphologically and metrically, although morphologic studies pose several problems such as difficulties with quantification and interobserver error. Geometric morphometrics is a relatively new method that allows better assessment of morphologic characteristics. This paper aims to investigate the usability of this method by assessing three different morphologic characteristics in a sample of South African blacks: shape of the greater sciatic notch, mandibular ramus flexure, and shape of the orbits. Relative warps, thin-plate splines, and canonical variates analysis (CVA) analyses were performed. As expected, the shape of the greater sciatic notch provided the best separation between the sexes. Surprisingly, however, the shape of the orbits performed better that ramus flexure. Several possible explanations for this result are possible, which include the possibility that orbit shape is more sexually dimorphic than previously expected, or that biological reality is not reflected by this technique. More research is, however, needed.     

A method for the rapid automated assessment of olfactory function

We have developed a strategy for the rapid high-throughput screening of odor responsivity in genetically altered mice (in fact, any experimentally altered animal). Specifically, the report presents the development and validation of a fully automated procedure based on the evaluation of an animal's stimulus-induced reflexive breathing response (i.e. sniffing behavior) to both air and odorant stimuli. The method requires no training of the animal to be screened and the outcome of the evaluation yields an operationally defined measure. Briefly, using whole-body plethysmography, the procedure determines the numerical values for a set of 14 respiratory measures in response to the presentation of air and a well-above-threshold concentration of the odorant propanol. These measures of stimulus-induced sniffing are incorporated into a model that defines a single univariate measure of response behavior, or 'Sniffing Index', for each screened animal. The approach significantly discriminated between the reflexive sniffing response of a control group of mice and that of an experimentally defined manipulated group for which, a priori, we expected to observe a robust altered breathing response to odorant stimulation (i.e. non-odor-aversion-conditioned versus odor-aversion-conditioned C57BL/6J mice). Further, the procedure was able to significantly discriminate between a mutant phenotype with documented alterations in physiologic and behavioral function (namely, the OMP-null mutant), and their background strain. In addition, applying epidemiologic screening principles to the observed data, we established an operational procedure for the evaluation of unknown animals.     

Clovis in context: New light on the peopling of the Americas

Until recently, the first Americans were thought to be fluted-point spear-hunters from the Siberian steppes. Near the end of the Ice Age, they followed big-game herds over the Bering land bridge into the open, upland habitats of the interior of North America about 12,000 years ago. Rapidly extinguishing the big game herds with their deadly hunting methods, they pressed southward in search of new herds and reached the tip of South America about a thousand years later. Today, nearly 70 years after the first excavations at Clovis, New Mexico, the type site for this culture, new sites and new dates from both North and South America are forcing a revision of the earlier picture of the migrations and adaptations of the first Americans. But despite recurring claims that human colonization of the Western Hemisphere began as early as 20,000 or more years ago with the arrival of generalized foragers lacking a projectile-point tradition, no definitive data gives empirical support for a human presence before c. 12,000 before the present (B.P.). All supposed pre-Clovis cultures except one in Alaska have failed to withstand careful scrutiny of their data. In addition, despite recent claims for cultural and biological links of the migrants to Europe or the Pacific Islands, the skeletons and cultural assemblages of Paleoindians throughout the hemisphere point consistently to a northeast Asian origin. According to new data, Paleoindian ancestors in Beringia c. 12,000 years ago were not specialized, fluted-point hunters of large game, but broad-spectrum hunter-gatherers using triangular or bipointed, lanceolates. Diverse cultures descended from these ancestors, not only the big-game hunting Clovis culture of the North American high plains. And just as Clovis did not set the cultural pattern for the hemisphere, it was not the earliest culture. Fully contemporary with the earliest possible Clovis dates of c. 11,200, in South America there already were maritime foragers on the Pacific coast, small-game hunters in the southern pampas, and tropical forest riverine foragers in the eastern tropical lowlands. The Clovis culture thus was just one of several regional cultures developed in the millennium after the initial migration. It could not have been the ancestor of the other early Paleoindian cultures. This new picture of Paleoindian cultures changes understanding of initial human adaptive radiation in the Americas and has implications for general theories of human evolution and behavioral ecology.     

A morphometric and taxonomic assessment of a hominine femur from the lower member,Koobi Fora,Lake Turkana

Previous research by this author and others has indicated that species-level differentiation within the hominines can be detected in the femur. The femoral shaft of Homo erectus, relative to H. sapiens, demonstrates small anteroposterior diameters, a distally placed point of minimum shaft breadth, and increased cortical thickness resulting in medullary stenosis. This pattern has been identified in specimens from Choukoutien (I and IV), Olduvai (OH 28), and Lake Turkana (KNM ER 737). Findings reported here include anatomical comparisons and univariate and multivariate analyses based on external and internal shaft morphology. These results indicate that the femoral pattern characteristic of H. erectus can be identified in KNM ER 1481a recovered at Lake Turkana below the KBS tuff. Recent dating of that tuff indicates a date of ca. 1.8 mya, thereby yielding a date for KNM ER 1481a of ? 2.0 mya. Known H. erectus femora extend over a broad span and yet show very low, variability; this pronounced stasis would strongly suggest that, at least in this portion of the postcranium, H. erectus was in a period of profound morphological stasis.     

Imaging system for morphometric assessment of absorption or fluorescence in stained cells

An image acquisition and processing system has been developed for quantitative microscopy of absorption or fluorescence in stained cells. Three different light transducers are used in the system to exploit the best characteristics of these sensors for different biological measurements. A digital scanner, in the form of a linear array charge-coupled device (CCD), acquires data with high spatial and photometric resolution. A color (RGB) camera is employed when spectral information is required for the segmentation of cellular subcomponents. An image-intensified charged-injection device (CID) camera provides for very low light intensity measurements, primarily for fluorescence-labeled cells. Properties of these transducers, such as contrast transfer function, linearity, and photo-response nonuniformity, have been measured. Two dedicated image processing units were incorporated into the system. The front-end processor, based on a digital signal processor, provides functions such as object detection, raw image calibration, compression, artifact removal, and filtering. The second image processor is associated with the frame memory and includes a histogram processor, a dedicated arithmetic logic unit for image processing functions, and a graphics module for one-bit overlay functions. An interactive program was developed to acquire cell images and to experiment with a range of segmentation algorithms, feature extractions, and other image processing functions. The results of any image operation are displayed on the video monitor. Once a desired processing sequence is determined, the sequence may be stored to become part of a command library and can be executed thereafter as a single instruction.     

A morphometric study of primary adenocarcinoma of the vagina

Primary adenocarcinoma of the vagina accounts for approximately 1% of all invasive carcinomas of the female genital tract. This paper reports on a study of four cases of primary adenocarcinoma (including one with in utero diethylstilbestrol exposure) of the vagina from the files of the Medical University of South Carolina. Both tissue sections and cytologic preparations from each case were evaluated in order to delineate the morphologic characteristics of the cells that compose the lesions. Histologically, the lesions primarily presented the tubular cystic pattern; solid and papillary growth patterns were also seen in one case. The constituent cells included clear cells, hobnail cells and secretory and nonsecretory tubular cystic cells. All specimens were examined for the following parameters: cell population, nuclear area, cytoplasmic area, nuclear/cytoplasmic (N/C) proportions, nuclear and cytoplasmic characteristics. While a fairly detailed profile of the morphologic criteria for hobnail cells was developed, the cellular profiles of the other malignant glandular cells originating in primary vaginal adenocarcinoma remain less certain.     

A new morphometric analysis of the hominid pelvic bone

This study is based upon a new morphometric technique providing both size and shape variables. It has been applied to 189 pelvic bones of extant humans and African apes as well as to 13 hominid pelvic bones of various taxonomic status. The main aim of this work is to include such fossil bones in the same study in order to set a synthetic comparison of their shape in the light of the yardstick given by the African ape/human pelvic bone comparison. To do so, ratio diagrams are chosen because they are simple and very expressive tools with which to present such comparisons. Shape differences are very well illustrated and quantified by this technique. The ilium appears to be the most different of the three parts of the pelvic bone. Compared to these differences, discrepancies between fossil hominid and extant human bones are of a totally different scale. This shows the architectural unity related to the acquisition of bipedalism by hominids. It is nonetheless possible to detect two levels of difference. The first separates Australopithecus from Homo and could be seen as reflecting locomotor differences between both genera. The second splits both Homo erectus and Neanderthal from modern human pelvic bones. It appears from the hominid fossil record of pelvic bones that two periods of stasis exist and are separated by a period of very rapid evolution corresponding to the emergence of the genus Homo. We are of the opinion that the same could be true for the split between African ape and hominid lineages at the end of the Miocene.     

A morphometric and comparative study of the malleus.

This study has attempted to research, in detail, the dimensions and form of the malleus, and to indicate possible differences with regard to race, sex and side of origin (left or right). The ossicles were obtained from 75 adult cadavers and the dimensions were determined with the aid of a reflection microscope. Clear statistically significant differences were found between the Negroid and Caucasoid races, as well as between the right and left ossicles. No meaningful differences were determined between male and female ossicles.     

A foliar morphometric approach to the study of salicaceae

An assemblage of leaves of four species of willows (Salix viminalis, S. alba, S. fragilis, andS. caprea), two of their hybrids (S. alba ×fragilis andS. caprea ×viminalis), two species of poplars (Populus alba andP. tremula), and two “external” species (Elaeagnus angustifolia andPyrus salicifolia) was analyzed. The study was designed to determine whether leaves that are very close in shape but belong to different species, particularly the elongated leaves ofS. viminalis, S. alba, S. fragilis, E. angustifolia, andP. salicifolia, could be discriminated by continuous foliar characters (that is, vegetative characters), despite both the great foliar polymorphism met in Salicaceae (especially in the genusPopulus) and hybridization problems. Our results show that multivariate analyses (principal component analysis [PCA] and cluster analysis) of an appropriate character set enable leaves to be classified in their own species at more than 98 %, even in these difficult conditions. It can be seen from this work that PCA is a good tool when it keeps a maximum of total variability; that is, when there are few taxa; on the other hand, cluster analysis is more appropriate with many taxa. One can then envisage the application of this morphometric approach to fossil-imprint determination, in which even fragmentary paleobotanical remains could be included. This would give access to real biodiversity of tertiary flora and to intraspecific variability.

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Résumé  Un assemblage de feuilles de quatre espèces de saules (Salix viminalis, S. alba, S. fragilis, etS. caprea), deux de leurs hybrides (S. alba ×fragilis etS. caprea ×viminalis), ainsi que deux espèces de peupliers (Populus alba etP. tremula), et deux espèces “externes” (Elaeagnus angustifolia etPyrus salicifolia) a été étudié. Le but était de savoir si des feuilles de forme très proche mais d’espèces différentes (en particulier les feuilles allongées deS. viminalis, S. alba, S. fragilis, E. angustifolia, etP. salicifolia) pouvaient être discriminées par des caractères foliaires (donc végétatifs) continus, et ce malgré le très grand polymorphisme foliaire existant chez les Salicacées (surtout chez le genrePopulus), et les problèmes d’hybridation. Il en a résulté que les analyses multivariées (ACP et analyse agrégative) associées à un jeu de caractères approprié, permettent à plus de 98% le classement des feuilles dans leur propre espèce, même dans ces conditions difficiles. Il ressort de ce travail que l’ACP n’est un bon outil que lorsqu’ elle conserve un maximum de la variabilité totale, c’est-à-dire ici, quand les taxa sont peu nombreux; en revanche, l’analyse agrégative exprime le maximum de ses capacités en présence d’un grand nombre de taxa. On peut alors envisager l’application de cette approche morphométrique à la détermination d’empreintes fossiles, dans le but d’inclure même les restes fragmentaires dans les études paléobotaniques, ce qui donnerait accès à la réelle biodiversité des flores tertiaires et à la variabilité existant au sein des espèces.

     

A morphometric study of the lungs of different sized bats: correlations between structure and function of the chiropteran lung.

1. The lungs of four species of bats, Phyllostomus hastatus (PH, mean body mass, 98 g), Pteropus lylei (PL, 456 g), Pteropus alecto (PA, 667 g), and Pteropus poliocephalus (PP, 928 g) were analysed by morphometric methods. These data increase fivefold the range of body masses for which bat lung data are available, and allow more representative allometric equations to be formulated for bats. 2. Lung volume ranged from 4.9 cm3 for PH to 39 cm3 for PP. The volume density of the lung parenchyma (i.e. the volume proportion of the parenchyma in the lung) ranged from 94% in PP to 89% in PH. Of the components of the parenchyma, the alveoli composed 89% and the blood capillaries about 5%. 3. The surface area of the alveoli exceeded that of the blood-gas (tissue) barrier and that of the capillary endothelium whereas the surface area of the red blood cells as well as that of the capillary endothelium was greater than that of the tissue barrier. PH had the thinnest tissue barrier (0.1204 microns) and PP had the thickest (0.3033 microns). 4. The body mass specific volume of the lung, that of the volume of pulmonary capillary blood, the surface area of the blood-gas (tissue) barrier, the diffusing capacity of the tissue barrier, and the total morphometric pulmonary diffusing capacity in PH all substantially exceeded the corresponding values of the pteropid species (i.e. PL, PA and PP). This conforms with the smaller body mass and hence higher unit mass oxygen consumption of PH, a feature reflected in the functionally superior gas exchange performance of its lungs. 5. Morphometrically, the lungs of different species of bats exhibit remarkable differences which cannot always be correlated with body mass, mode of flight and phylogeny. Conclusive explanations of these pulmonary structural disparities in different species of bats must await additional physiological and flight biomechanical studies. 6. While the slope, the scaling factor (b), of the allometric equation fitted to bat lung volume data (b = 0.82) exceeds the value for flight VO2max (b = 0.70), those for the surface area of the blood-gas (tissue) barrier (b = 0.74), the pulmonary capillary blood volume (b = 0.74), and the total morphometric lung diffusing capacity for oxygen (b = 0.69) all correspond closely to the VO2max value. 7. Allometric comparisons of the morphometric pulmonary parameters of bats, birds and non-flying mammals reveal that superiority of the bat lung over that of the non-flying mammal.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ecological correlates and evolutionary divergence in the skull of turtles: a geometric morphometric assessment

Resource use and phylogeny are often correlated with morphological variation. Moreover, because biological shapes are often complex and evolve depending on several internal constraints, they must be assessed using integrative methods. We analyzed the morphological variation of the turtle skull in the context of an adaptive radiation. Our focus are turtles of the superfamily Testudinoidea, which are remarkably diverse, both in number of species and in ecology. In this study, we depict morphological variation in the turtle skull in three dimensions with respect to diet, phylogeny, and habitat using modern geometric morphometrics. Our study revealed that morphological specialization was related to both diet and habitat. Morphological variation is decomposed in regard of both resource use (habitat and diet) and phylogeny. Feeding mode depending on environment was suggested as a key factor determining morphological evolution and diversification of turtle skulls. Diet (especially durophagy) leads to parallel morphologies in different clades. Phylogeny seemed to constrain only localized features of the skull and remained of minor influence, because overall morphotypes, closely correlated with ecological factors, occurred in both clades. In conclusion, the adaptive radiation of the Testudinoidea is revealed to demonstrate a clear relationship between the skull shape and life style.