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Morphometric Techniques (morphometric + techniques)
Kinds of Morphometric Techniques Selected AbstractsEthanol neurotoxicity and dentate gyrus developmentCONGENITAL ANOMALIES, Issue 3 2008Takanori Miki ABSTRACT Maternal alcohol ingestion during pregnancy adversely affects the developing fetus, often leading to fetal alcohol syndrome (FAS). One of the most severe consequences of FAS is brain damage that is manifested as cognitive, learning, and behavioral deficits. The hippocampus plays a crucial role in such abilities; it is also known as one of the brain regions most vulnerable to ethanol-induced neurotoxicity. Our recent studies using morphometric techniques have further shown that ethanol neurotoxicity appears to affect the development of the dentate gyrus in a region-specific manner; it was found that early postnatal ethanol exposure causes a transitory deficit in the hilus volume of the dentate gyrus. It is strongly speculated that such structural modifications, even transitory ones, appear to result in developmental abnormalities in the brain circuitry and lead to the learning disabilities observed in FAS children. Based on reports on possible factors deciding ethanol neurotoxicity to the brain, we review developmental neurotoxicity to the dentate gyrus of the hippocampal formation. [source] The use of GIS-based digital morphometric techniques in the study of cockpit karstEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2007P. Lyew-Ayee Abstract Cockpit karst landscapes are among the most distinctive landscapes in the world, and have been the focus of long-standing scientific interest. Early researchers used largely descriptive techniques to categorize the terrain, and subsequent work has not attempted to critically re-evaluate descriptions of landscapes using more sophisticated methods. The distinctive surface topography of cockpit karst areas can be characterized in order to compare them with other karst as well as non-karst areas, and to determine geological and/or climatic conditions that are responsible for the observed terrain. Process models of the rate of karst denudation or evolution can only be accurate if the contemporary morphology of the landscape is quantitatively and unambiguously defined. A detailed analysis of cockpit karst terrain is carried out using the latest GIS-based digital morphometric techniques in order to assess the nature of such terrain and provide further information for subsequent modelling, as well as other non-geomorphological applications, such as environmental management and conservation issues. The paper presents the methodology used for the digital analysis of terrain and landforms in the distinctive Cockpit Country area of Jamaica and its environs. The results indicate that cockpit karst may be categorized based on its vertical, horizontal and shape characteristics, as well as by looking at the semivariogram, slope characteristics, and landscape relief scale, which combine measures of vertical and horizontal scales. Copyright © 2006 John Wiley & Sons, Ltd. [source] Heritability of human cranial dimensions: comparing the evolvability of different cranial regionsJOURNAL OF ANATOMY, Issue 1 2009Neus Martínez-Abadías Abstract Quantitative craniometrical traits have been successfully incorporated into population genetic methods to provide insight into human population structure. However, little is known about the degree of genetic and non-genetic influences on the phenotypic expression of functionally based traits. Many studies have assessed the heritability of craniofacial traits, but complex patterns of correlation among traits have been disregarded. This is a pitfall as the human skull is strongly integrated. Here we reconsider the evolutionary potential of craniometric traits by assessing their heritability values as well as their patterns of genetic and phenotypic correlation using a large pedigree-structured skull series from Hallstatt (Austria). The sample includes 355 complete adult skulls that have been analysed using 3D geometric morphometric techniques. Heritability estimates for 58 cranial linear distances were computed using maximum likelihood methods. These distances were assigned to the main functional and developmental regions of the skull. Results showed that the human skull has substantial amounts of genetic variation, and a t -test showed that there are no statistically significant differences among the heritabilities of facial, neurocranial and basal dimensions. However, skull evolvability is limited by complex patterns of genetic correlation. Phenotypic and genetic patterns of correlation are consistent but do not support traditional hypotheses of integration of the human shape, showing that the classification between brachy- and dolicephalic skulls is not grounded on the genetic level. Here we support previous findings in the mouse cranium and provide empirical evidence that covariation between the maximum widths of the main developmental regions of the skull is the dominant factor of integration in the human skull. [source] The effects of muscular dystrophy on the craniofacial shape of Mus musculusJOURNAL OF ANATOMY, Issue 6 2007Donna Carlson Jones Abstract Skeletal anomalies are common in patients with muscular dystrophy, despite an absence of mutations to genes that specifically direct skeletogenesis. In order to understand these anomalies further, we examined two strains of muscular dystrophy (laminin- and merosin-deficient) relative to controls, to determine how the weakened muscle forces affected skull shape in a mouse model. Shape was characterized with geometric morphometric techniques, improving upon the limited analytical power of the standard linear measurements. Through these techniques, we document the specific types of cranial skeletal deformation produced by the two strains, each with individual shape abnormalities. The mice with merosin deficiency (with an earlier age of onset) developed skulls with more deformation, probably related to the earlier ontogenetic timing of disease onset. Future examinations of these mouse models may provide insight regarding the impact of muscular forces and the production and maintenance of craniofacial integration and modularity. [source] Morphometric comparison of the cephalic region of cultured Acipenser baerii (Brandt, 1869), Acipenser naccarii (Bonaparte, 1836) and their hybrid,JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2006C. Costa Summary Geometric morphometric techniques were used in the characterization of morphological differences of the cranial region in cultured Acipenser baerii and A. naccarii and their hybrid. Species identification in sturgeons sometimes is difficult, because of the morphological plasticity of individual variability and the small differences between taxa. Identification is also complicated by human intervention and manipulation (e.g. aquaculture, hybridization, pollution). This study indicates how the differences between two species and their hybrids can be quantified and accurately visualized via geometric morphometrics. This technique may serve as a useful methodology to supplement analytical studies on morphometrics and systematics in Acipenseridae. [source] Multivariate and geometric morphometrics in the analysis of sexual dimorphism variation in Podarcis lizardsJOURNAL OF MORPHOLOGY, Issue 2 2007Antigoni Kaliontzopoulou Abstract Podarcis bocagei and P. carbonelli are two closely related lacertid species, very similar morphologically and ecologically. We investigated sexual dimorphism patterns presented by both species in allopatry and in sympatry. Sexual size and shape dimorphism patterns were analyzed using both multivariate and geometric morphometric techniques. Multivariate morphometrics revealed a marked sexual dimorphism in both species,males being larger with more robust habitus and females presenting a longer trunk. General patterns of sexual size dimorphism are not modified in sympatry, although there is evidence for some morphological change in male head size. The application of geometric morphometrics offered a more detailed image of head shape and revealed that males present a more developed tympanic area than do females, while females have a more rounded head. Differences in the degree of sexual shape dimorphism were detected in sympatry, but no consistent patterns were observed. From the results of the study, and based on previous knowledge on the populations studied, we conclude that the morphological differences observed are probably not caused by exploitative competition between the species, but rather appear attributable to the modification of the relative influence of sexual and natural selection on both sexes. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source] Variation and causal factors of craniofacial robusticity in Patagonian hunter-gatherers from the late HoloceneAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 6 2006Valeria Bernal Fueguian-Patagonian skulls have been characterized as some of the most robust of any modern crania. However, the causal factors of such robusticity remain unsettled. We assess within- and among-sample cranial robusticity of seven samples from continental Patagonia and Tierra del Fuego, using geometric morphometric techniques. In addition, the biomechanical, phylogenetic, and climatic hypotheses proposed to account for robusticity in such samples are discussed. Two Amerindian samples of farmers and two early middle Holocene samples from South America were included. The results show: 1) large variation in craniofacial robusticity among Patagonian samples, with the highest robusticity in samples from south continental Patagonia and Isla Grande of Tierra del Fuego, whereas central and north Patagonian samples display the same degree of robusticity as farmer samples; 2) that early middle Holocene samples display lower levels of robusticity than South Patagonian samples; and 3) strong association between latitude and craniofacial robusticity, with the most robust craniofacial morphologies occurring at the highest latitudes. In consequence, neither masticatory stress nor retention of ancestral features is supported by the morphological evidence analyzed. Hence it is hypothesized that endocrine changes related to cold climate may be a plausible explanation for several craniofacial features found in Fueguian and south continental Patagonian samples, such as their large masticatory component, and pronounced supraorbital ridge and glabellar region. Am. J. Hum. Biol. 18:748,765, 2006. © 2006 Wiley-Liss, Inc. [source] Genetic, geographic, and environmental correlates of human temporal bone variationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2007Heather F. Smith Abstract Temporal bone shape has been shown to reflect molecular phylogenetic relationships among hominoids and offers significant morphological detail for distinguishing taxa. Although it is generally accepted that temporal bone shape, like other aspects of morphology, has an underlying genetic component, the relative influence of genetic and environmental factors is unclear. To determine the impact of genetic differentiation and environmental variation on temporal bone morphology, we used three-dimensional geometric morphometric techniques to evaluate temporal bone variation in 11 modern human populations. Population differences were investigated by discriminant function analysis, and the strength of the relationships between morphology, neutral molecular distance, geographic distribution, and environmental variables were assessed by matrix correlation comparisons. Significant differences were found in temporal bone shape among all populations, and classification rates using cross-validation were relatively high. Comparisons of morphological distances to molecular distances based on short tandem repeats (STRs) revealed a significant correlation between temporal bone shape and neutral molecular distance among Old World populations, but not when Native Americans were included. Further analyses suggested a similar pattern for morphological variation and geographic distribution. No significant correlations were found between temporal bone shape and environmental variables: temperature, annual rainfall, latitude, or altitude. Significant correlations were found between temporal bone size and both temperature and latitude, presumably reflecting Bergmann's rule. Thus, temporal bone morphology appears to partially follow an isolation by distance model of evolution among human populations, although levels of correlation show that a substantial component of variation is unexplained by factors considered here. Am J Phys Anthropol 2007. © 2007 Wiley-Liss, Inc. [source] Common patterns of facial ontogeny in the hominid lineageTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 3 2002Rebecca Rogers Ackermann Abstract Recent evaluation of Neanderthal and modern human ontogeny suggests that taxon-specific features arose very early in development in both lineages, with early, possibly prenatal, morphological divergence followed by parallel postnatal developmental patterns. Here we use morphometric techniques to compare hominoid facial growth patterns, and show that this developmental phenomenon is, in fact, not unique to comparisons between Neanderthals and modern humans but extends to Australopithecus africanus and to the hominoid lineage more broadly. This finding suggests that a common pattern of juvenile facial development may be more widespread and that the roots of ontogenetically early developmental differentiation are deep,perhaps predating the ape/human split of 6+ million years ago. Anat Rec (New Anat) 269:142,147, 2002. © 2002 Wiley-Liss, Inc. [source] A Landmark Analysis-Based Approach to Age and Sex Classification of the Skull of the Mediterranean Monk Seal (Monachus monachus) (Hermann, 1779)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2009C. Brombin Summary This work aimed at applying geometric morphometric analysis techniques to the skull of the Mediterranean monk seal (Monachus monachus, Hermann, 1779). Inferential analyses were performed using a non-parameteric permutation framework based on a series of skulls of different age classes belonging to individuals of both sexes. Our goal was to establish whether a statistical approach based on osteometric measurements and surface analysis of photographs of the left lateral plane of the skull may lead to a different and scientifically sound method of age and sex classification in this critically endangered marine mammal. Our data indicate that non-parametric combination methodology enables the researcher to give local assessment using a combination with domains. Developing geometric morphometric techniques in a non-parametric permutation framework could be useful in solving high dimensional and small sample size problems as well as classification problems, including zoological classification of specimens within a specific population. The Mediterranean monk seal is believed to be the world's rarest pinniped and one of the most endangered mammals of the world, with fewer than 600 individuals currently surviving. The use of shape analysis would allow new insights into the biological characteristics of the monk seal by simply extracting potentially new information on age and size from museal specimens. [source] Gross Anatomy of the Female Genital Organs of the Domestic Donkey (Equus asinus Linné, 1758)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2009T. F. P. Renner-Martin Summary Although donkeys play an important role as companion or pack and draught animals, theriogenological studies and anatomical data on the genital organs of the jenny are sparse. To provide anatomical descriptions and morphometric data, the organa genitalia feminina, their arteries and the ligamentum latum uteri of 10 adult but maiden jennies were examined by means of gross anatomical and morphometric techniques. In comparison with anatomical data of horses obtained from literature the genital organs of jennies appear to be more voluminous in relation to the body mass and the position of the ovaries is slightly further cranial than in mares. In asses, the ovaries contain large follicles reaching a diameter of up to 40 mm. The mesosalpinx is much wider than in the horse forming a considerably spacious bursa ovarica. The asinine ligamentum teres uteri reveals a very prominent cranial end, the ,appendix'. Tortuous mucosal folds occur in the wall of the jenny's cervical channel. The vascularization of the female genital organs of asses is very similar to that of horses. One of the examined specimens reveals a large mucosal fold dividing the cranial part of the vagina into a left and right compartment. [source] It is all in the head: morphological basis for differences in bite force among colour morphs of the Dalmatian wall lizardBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009KATLEEN HUYGHE Males of the lizard Podarcis melisellensis occur in three distinct colours that differ in bite performance, with orange males biting harder than white or yellow ones. Differences in bite force among colour morphs are best explained by differences in head height, suggesting underlying variation in cranial shape and/or the size of the jaw adductors. To explore this issue further, we examined variation in cranial shape, using geometric morphometric techniques. Additionally, we quantified differences in jaw adductor muscle mass. No significant differences in size corrected head shape were found, although some shape trends could be detected between the colour morphs. Orange males have relatively larger jaw adductors than yellow males. Not only the mass of the external jaw adductors, but also that of the internal jaw adductors was greater for the orange morph. Data for other cranial muscles not related to biting suggest that this is not the consequence of an overall increase in robustness in orange individuals. These results suggest that differences in bite performance among morphs are caused specifically by an increase in the mass of the jaw adductor, which may be induced by differences in circulating hormone levels. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 13,22. [source] | |||||||||||||