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Morphometric Approach (morphometric + approach)

Distribution by Scientific Domains
Life Sciences62%

Kinds of Morphometric Approach

  • geometric morphometric approach
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    Selected Abstracts

    A Geometric Morphometric Approach to Sex Determination of the Human Adult Os Coxa

    JOURNAL OF FORENSIC SCIENCES, Issue 4 2010
    Joan A. Bytheway Ph.D.
    Abstract:, Sex determination of the human skeleton is best assessed from the os coxa. The present study explored the possibility of using three-dimensional landmark coordinate data collected from various landmarks located over the entire bone to determine whether there were significant sex differences local to the landmarks. Thirty-six landmarks were digitized on 200 African American and European American male and female adult human os coxae. MANCOVA results show that sex and size have a significant effect on shape for both European Americans (Sex, F = 17.50, d.f. = 36, 63, p > F = 0.0001; Size, F = 2.56, d.f. = 36, 63, p > F = 0.0022) and African Americans (Sex, F = 21.18, d.f. = 36, 63, p > F = 0.0001; Size, F = 2.59, d.f. = 36, 63, p > F = 0.0005). The discriminant analysis shows that sexing accuracy for European Americans is 98% for both males and females, 98% for African American females, and 100% for African American males. [source]

    CONVERGENCE AND REMARKABLY CONSISTENT CONSTRAINT IN THE EVOLUTION OF CARNIVORE SKULL SHAPE

    EVOLUTION, Issue 5 2007
    Stephen Wroe
    Phenotypic similarities between distantly related marsupials and placentals are commonly presented as examples of convergence and support for the role of adaptive evolution in shaping morphological and ecological diversity. Here we compare skull shape in a wide range of carnivoran placentals (Carnivora) and nonherbivorous marsupials using a three-dimensional (3-D) geometric morphometric approach. Morphological and ecological diversity among extant carnivorans is considerably greater than is evident in the marsupial order Dasyuromorphia with which they have most commonly been compared. To examine convergence across a wider, but broadly comparable range of feeding ecologies, a dataset inclusive of nondasyuromorphian marsupials and extinct taxa representing morphotypes no longer present was assembled. We found support for the adaptive paradigm, with correlations between morphology, feeding behavior, and bite force, although skull shape better predicted feeding ecology in the phylogenetically diverse marsupial sample than in carnivorans. However, we also show that remarkably consistent but differing constraints have influenced the evolution of cranial shape in both groups. These differences between carnivorans and marsupials, which correlate with brain size and bite force, are maintained across the full gamut of morphologies and feeding categories, from small insectivores and omnivores to large meat-specialists. [source]

    A morphometric approach to the geographic variation of the terrestrial isopod species Armadillo tuberculatus (Isopoda: Oniscidea)

    JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2009
    M. Kamilari
    Abstract The terrestrial isopod species Armadillo tuberculatus Vogl, 1876 (Crustacea, Isopoda, Oniscidea) is a widely polymorphic species distributed in the south-central Aegean region (Greece) with a different morph on each island. Variation consists in coloration, size of cuticular tubercules, shape of telson and the shape of the male first pleopod exopodite (secondary sexual character of taxonomic importance). We studied the allometric growth of a cuticular tubercule in 17 populations (for both male and female individuals) and the shape variation of the first male pleopod exopodite in 10 populations using Elliptic Fourier Analysis, in order to test for patterns of intraspecific variation and possible relationships between morphs. In addition, Thin Plate Spline analysis was used for the calculation of the minimum bending energy between different exopodite shapes, which was then used for estimating the minimum spanning network (MSN) connecting them. The different allometric growth rates of the tubercule among island groups were significantly related to island latitude and climatic factors. On the other hand, the clustering of islands and the MSN based on male exopodite shape differences were not related to the palaeogeography of the Aegean region or to the present geographic distances of islands. These results are interpreted as evidence for non-adaptive radiation of the morphs. Resumen El isópodo terrestre Armadillo tuberculatus Vogl, 1876 (Crustacea, Isopoda, Oniscidea) es una especie extensamente polimórfica distribuida por la región sur-central del piélago Egéo (Grecia), con una forma distinta en cada isla. Se trata de variaciones en la coloración, el tamaño de los tubérculos cuticulares y en la forma del primer exopodio masculino del pleopodo (carácter sexual secundario de importancia taxonómica). Estudiamos el crecimiento alométrico del tubérculo cuticular en 17 poblaciones (en individuos de ambos sexos) y la variación de la forma del primer exopodio masculino del pleopodo en 10 poblaciones según el análisis de Fourier elíptico (Elliptic Fourier Analysis) para detectar patrones de variación intraespecifica y relaciones posibles entre las formas de la especie. Además, el análisis Thin Plate Spline fue utilizado para el cálculo de la Energía de Flexión Mínima (Minimum Bending Energy) entre diversas formas del exopodio, que entonces fue utilizada para estimar la Mínima Red de Distancias (Minimum Spanning Network, MSN) que las conectaba. Detectamos una correlación significativa entre las diversas tasas de crecimiento alométrico del tubérculo entre los grupos de islas y la latitud de la isla. Por otro lado, la agrupación de las islas y la MSN, basada en las diferencias de la forma del exopodio, no fueron relacionados con la paleogeografía de la región del piélago Egéo ni con las actuales distancias geográficas de las islas. Estos resultados se interpretan como evidencia para la radiación non-adaptativa de las diversas formas de la especie. [source]

    A quantitative comparison of the ontogeny of two closely-related Upper Devonian phacopid trilobites

    LETHAIA, Issue 2 2005
    CATHERINE CRÔNIER
    The best insight into the development of Devonian phacopids has been obtained from Trimerocephalus lelievrei Crônier & Feist, 1997, a Famennian phacopine from Morocco, where changes in size and shape have been quantified. In this study, a morphometric approach has been used: (1) to retrodeform and then establish patterns of morphological variation in a well preserved but tectonically deformed assemblage belonging to another phacopine species Weyerites ensae (Richter & Richter, 1926), a Famennian phacopine from Thuringia, and (2) to establish patterns of developmental and evolutionary changes within two closely related species: Weyerites ensae and Trimerocephalus lelievrei. The method of retrodeformation using a set of discrete points presumed to be homologous on all studied individuals, has demonstrated that the next analyses are possible on the retrodeformed material as compared to the undeformed material. Morphometric analysis based on outline analysis has permitted demonstration of progressive shape change in agreement with ontogenetic ordination and a comparison of changes in size and shape in Weyerites ensae. The main changes in shape appear to occur in the meraspid period, whereas increase in size takes place mainly in the holaspid period. This pattern, already reported for Trimerocephalus lelievrei, can be generalized for phacopine trilobites from the Late Devonian. Moreover, the comparison of the two ontogenetic trajectories has shown that most of the differences are related to ,structural' changes, probably linked to a relative pre- post-displacement. The results suggest that ecological adaptation may be studied by examining the changes in development that occur within species through time and space. [source]

    A geometric morphometric approach to the quantification of population variation in sub-Saharan African crania

    AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010
    Daniel Franklin
    We report here on new data examining cranial variation in 18 modern human sub-Saharan African populations. Previously, we investigated variation within southern Africa; we now extend our analyses to include a series of Central, East, and West African crania, to further knowledge of the relationships between, and variation and regional morphological patterning in, those populations. The sample comprises 377 male individuals; the three-dimensional coordinates of 96 landmarks are analyzed using Procrustes-based methods. Interpopulation variation is examined by calculating shape distances between groups, which are compared using resampling statistics and parametric tests. Phenotypic variance, as a proxy for genetic variance, is measured and compared across populations. Principal components and cluster analyses are employed to explore relationships between the populations. Shape differences are visualized using three-dimensional rendered models. Observed disparity patterns imply a mix of differences and similarities across populations, with no apparent support for genetic bottlenecks, which is likely a consequence of migrations that may have influenced differences in cranial form; supporting data are found in recent molecular studies. The Pygmy sample had the most distinctive cranial morphology; characteristically small in size with marked prognathism. These features characterized, although less strongly, the neighboring Bateke, and are possibly related to similar selective pressures in conjunction with interbreeding. Small cranial size is also involved in the considerable distinctiveness of the San and Khoikhoi. The statistical procedures applied in this study afford a powerful and robust means of quantifying and visualizing the magnitude and pattern of cranial variation between sub-Saharan African populations. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source]

    Prezygapophyseal articular facet shape in the catarrhine thoracolumbar vertebral column,

    AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2010
    Gabrielle A. Russo
    Abstract Two contrasting patterns of lumbar vertebral morphology generally characterize anthropoids. "Long-backed" monkeys are distinguished from "short-backed" apes [Benton: The baboon in medical research, Vol. 2 (1967:201)] with respect to several vertebral features thought to afford greater spinal flexibility in the former and spinal rigidity in the latter. Yet, discussions of spinal mobility are lacking important functional insight that can be gained by analysis of the zygapophyses, the spine's synovial joints responsible for allowing and resisting intervertebral movements. Here, prezygapophyseal articular facet (PAF) shape in the thoracolumbar spine of Papio, Hylobates, Pongo, Gorilla, and Pan is evaluated in the context of the "long-backed" versus "short-backed" model. A three-dimensional geometric morphometric approach is used to examine how PAF shape changes along the thoracolumbar vertebral column of each taxon and how PAF shape varies across taxa at corresponding vertebral levels. The thoracolumbar transition in PAF shape differs between Papio and the hominoids, between Hylobates and the great apes, and to a lesser extent, among great apes. At the level of the first lumbar vertebra, the PAF shape of Papio is distinguished from that of hominoids. At the level of the second lumbar vertebra, there is variation to some extent among all taxa. These findings suggest that morphological and functional distinctions in primate vertebral anatomy may be more complex than suggested by a "long-backed" versus "short-backed" dichotomy. Am J Phys Anthropol 142:600,612, 2010. © 2010 Wiley-Liss, Inc. [source]

    Does Erectile Tissue Angioarchitecture Modify with Aging?

    THE JOURNAL OF SEXUAL MEDICINE, Issue 4 2008
    An Immunohistological, Morphometric Approach
    ABSTRACT Introduction., Erectile dysfunction is a common problem in aged men; however, which vascular cavernosal alterations occur with age progression remain unclarified. Aim., Using cavernosal tissue from rats of various ages, we aimed to thoroughly assess erectile vascular-associated morphologic, immunohistological, and morphometric alterations during aging. Methods., Male Wistar rats were divided according to age in groups of 2, 6, 12, 18, 24 months old (N = 5). Cavernosal tissue of all groups was collected and processed for morphologic evaluation, immunodetection of ,-smooth muscle actin and von Willebrand factor and morphometric quantification of vascular and smooth muscle cell (SMC) areas. Main Outcome Measures., The morphometric assessment of age-related alterations in cavernosal vascular and SMCs using the ImageJ image-processing program. Results., Morphologic and immunohistological evaluation showed a similar structure of erectile tissue among all age groups, divided in two cavernosal bodies containing numerous sinusoidal vascular spaces surrounded by SMCs. Additionally, we observed a reduction of SMC content and an increase in the caliber of vascular spaces, with aging. This was confirmed by the morphometric quantification of the vascular and SMC areas (mean area ×103 µm2 ± ×103 standard error). Two-month-old animals had a mean vascular area of 4.21 ± 0.51, approximately 3.5-fold less than the 6-month-old group. The differences increased when comparing the youngest groups with the 12-, 18-, and 24-month-old animals, with mean measurements of 18.99 ± 1.91, 25.23 ± 2.76, and 26.34 ± 2.97. Conversely, SMC areas progressively decreased between 2- and 6-month-old animals, from 6.75 ± 0.90 to 6.38 ± 1.24. The elderly 12-, 18-, and 24-month-old groups presented an approximated 1.5-fold reduction on SMCs area, showed by the respective measurements of 4.11 ± 0.50, 4.01 ± 0.35, and 4.02 ± 0.44. Conclusions., We demonstrated that cavernosal angioarchitecture was modified with aging. The decrease in SMCs and the considerable enlargement of vascular lumens may limit the basic function of penile vascular tree in the elderly. Costa C, and Vendeira P. Does erectile tissue angioarchitecture modify with aging? An immunohistological and morphometric approach. J Sex Med 2008;5:833,840. [source]

    Variation in the digging apparatus of the subterranean silvery mole-rat, Heliophobius argenteocinereus (Rodentia, Bathyergidae): the role of ecology and geography

    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
    IOVÁ, LENKA BAR
    The skull of most subterranean tooth-digging rodents is markedly affected by their digging mode. In the present study, we investigated the cranial variation in a strictly subterranean, highly specialized Afrotropical tooth-digger, Heliophobius argenteocinereus (Bathyergidae, Rodentia), using a geometric morphometric approach and evaluated the effect of different factors on size and shape differences among four populations. No evidence for sexual dimorphism was found in skull size or shape. The cranial shape variation was large and influenced mainly by the type of habitat (miombo woodland versus farmland and grassland) and the latitudinal gradient. The dorsal side of the skull appears to be more plastic and adaptable to local environments, as well as more independent of size, than the ventral side. Only the shortening of the rostrum is presumably an adaptive process independent of size that leads to an increase of efficacy of the tooth-digging apparatus in Heliophobius, whereas the increase in the in-force and the more procumbent incisors both comprise size-related changes caused by ontogenetic allometric growth. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 822,831. [source]